ĦMR.AWESOME!

iTrader: (2)

Hello. I've failed the emissions test 5 times since May. On the first test, the HC were well below the limit. I just failed the NO. I replaced the EGR valve and then NO was good but I failed HC by 1ppm. The inspector tested again 2 hours later without changing anything and the HCs were through the roof. How could this be?

I replaced O2 sensor and spark plugs. Found that one of the AIR check valves was bad as well as the AIR control solenoid box thing so I replaced both of those. The base timing was retarded so I put that back to 0TDC (where it should be). The car has more power than it's had and idles better than it has in a few years. I just keep failing because of that got dang HCs. Compression is good. Vacuum is good. Purge canister is good.

Oh, and in the summer, the radiator drain **** stopper fell out while I was driving and all the coolant drained out and then a big cloud of steam engulfed my car. I limped home by driving a few miles and then stopping for 30mins to let it cool down. Could this have burned up my cat?

So now I'm wondering if I pull the timing back, will the HCs go down? Anything else to try?

Thanks, y'all.

mlbinseattle

How old is the catalytic converter? Assuming the engine is mechanically/electrically sound and not throwing any codes and all emissions parts are working correctly, then I would suspect the CC. Also, if it got super hot at any point in time, it may have gotten damaged. Most likely, it's old and is in need of replacement.

ĦMR.AWESOME!

iTrader: (2)

The CC is 2-3 years old. I replaced it last time I had to do emissions (2.5years ago). But, yeah, the engine overheated...hardcore. When i replaced the spark plugs, the old ones had a bit of white on the opposite side of the electrode. The same side as the gap. The white wasn't on the electrode itself, it was on the insulation. I'm also getting black soot buildup on the tailpipe. I didn't get that before I 'fixed' the timing.

mlbinseattle

Sounds like the spark plugs were overheating which can be caused by several things:

Ignition timing too far advanced
Air/fuel mixture too lean
Insufficient cooling water/lubricants
Plug not tightened enough
Use of a too hot spark plug

Ensure you use the right plugs, but also try setting the timing to where it fires before it reaches TDC ... maybe somewhere around 4-6 degrees BTDC and see what happens. On most engines, fire occurs before the piston reaches the end of the compression stroke thereby allowing the ignited gases to expand while being compressed. This not only allows for all or most of the gas mixture to get burnt, but it also provides the best energy transfer. Hydrocarbons that show up on an emissions test is basically the unburnt gas.
Specs are written for a variety of scenarios and circumstances. What I do is retard the timing until I get "ping" under load and then back off (advance) several degrees until the pinging goes away. You may need to set the timing, drive it under load (find a good hill and do some acceleration), and repeat until you find the ideal spot. If it pings, it will usually happen while accelerating.

If the engine is running to lean, it should be throwing a code(s). Of course, this is assuming that the O2 sensor/ECM is working properly. If it's running too lean, you might experience hesitation. Additionally, if it's running too lean, it can cause overheating, as well. Valves can get burnt and holes can get burnt into pistons. It's similar to the too far advanced timing or wrong plug problem.

If anyone else can think of anything I've left out, please feel free to add to this.

mlbinseattle

I also wanted to add that, after you ensure that the engine is doing what it's supposed to, the CC could still be damaged from the excessive heat that it experienced. But, I'm sure you'll find this out after you take it for emissions testing. It will either pass or it won't. Just ensure you have the engine issues taken care of, first, and ensure that the excessive heat problem is not repeating itself.

Personally, if it were my car, I'd compression test each cylinder and then put a pressure gauge on it while running just to see if everything was okay or if something possibly suffered because of the excessive heat.

ĦMR.AWESOME!

iTrader: (2)

Excellent. Thanks for the input. I'll try playing with the timing tomorrow, driving it around and seeing how it feels/smells.

I did do a compression test on each cylinder and they all got to 210psi within 4 strokes. They all got to 120 psi on the first stroke. Is that within normal operating tolerances? They also held that pressure for more than 5 seconds. I did not test while running, however.

I had a code 32 and 54 once, but I cleared it and it never returned.

I'm so close to never having to do emissions again. If I can just pass this year and then pass in Jan of next year and renew the registration for 2 years, my car will be 25y/o and therefore exempt by the next time emissions would be due.

mlbinseattle

Compression varies from one engine type to the next. On one type engine, it could read around 140 PSI and on another, 200 PSI. What you're looking for is that each cylinder is reading close to the others ... typically within +/- 10%. The running test I was talking about was to connect a pressure gauge to a vacuum intake to see if there's anything else that's happening. This test is not the same as compression testing. This is what I'm talking about: http://www.secondchancegarage.com/public/186.cfm 210 PSI is pretty good.

With respect to cylinder compression/leakdown, this article describes both pretty well: http://www.dietersmotorsports.com/Co...akdowntest.htm

I understand how you feel about emission testing, but this episode caused you take a hard look at the engine. Consider it a blessing.

ĦMR.AWESOME!

iTrader: (2)

Okey frickin dokey.

I played around with the timing a bunch yesterday and here are my results:

Setting the base timing to spec (0TDC) makes the engine do this weird noise. Almost like a noisy timing chain. It comes from the fron of the engine. It's a different noise than knocking. When I checked the timing after setting the base to 0TDC, the ecm had advanced the timing to about 4BTDC. It drives just fine with no knocking under any load. If I advance the base timing 4BTDC, I get no knocking ever. Base timing to 6BTDC gives me some knocking under load and 8BTDC gives me a lot of knocking under load.

Under normal idle conditions, where does the ecm try to keep the timing? 0TDC? Or does it usually advance it anyway?

I'm also looking in to my MAP sensor. Disconnecting it doesn't change the way the engine idles at first, but after awhile it sometimes stalls abruptly. I get 19"Hg vacuum going to the sensor. Ima go drive it around and mess with stuff more.

ASE doc

HCs are unburned fuel. Completely uncombusted, liquid carbon molecules. Not partially burned like CO, but completely unburned fuel that got through the engine without combusting. They are not created by incomplete combustion, and are therefore not reduced by increasing ignition lead. In fact, the opposite is true. Adding ignition lead will increase HC. Other things that increase HC production are lean AFR which leads to lean misfire, allowing unburned HC to pass through the engine. You may not even notice the engine misfiring, but you can see on a gas analyzer that leaning idle AFR beyond the correct level increases HC production.

This is where many less experienced technicians have a hard time with emissions tuning. Reducing fuel will reduce CO but at the same time, will increase HC. Too rich AFR will increase CO and HC. We get a carbureted vehicle to pass emissions by balancing the two. It makes sense that an engine that runs smoother would produce less emissions, but that is not always the case. Of course, any engine that misfires for any reason will produce excessive HC. In order to pass emissions an engine must generally run well, unless you just want to throw new catalyst at it , which will soon be ruined by excessive emissions from the engine.

Some HC from the engine is normal. It is the intention of the engineers that this HC be reacted to CO2 in the exhaust system, primarily in the manifolds, which should be hot enough to react the HC. Too advanced timing will cool the manifolds and increase HC output at the tail pipe. You can watch this happen when I have a vehicle on the gas analyzer. Add timing lead, and you can watch HC increase. Reduce lead and HC reduces. Even though the engine may not idle as well, HC will be reduced by heating of the exhaust manifolds. To get the full effect of this, I may have to run the engine up to 1,800rpm for several seconds to increase manifold temp. On early vehicles, with less stringent standards(2.0% CO and 220ppm HC), the reaction of the exhaust gases in the manifolds is sufficient to produce passing emissions. Newer vehicles have more stringent standards and require the help of additional devices to reduce emissions to passing standards. The EGR has been around a while and as you already know, reduces NOX by reducing combustion temps. The reduced temps also increases HC but, again, the hot exhaust manifolds serve to process the increased HC. CO production is almost solely a function of AFR. Leaner AFR reduces CO. The hot exhaust manifolds also react CO in the exhaust. Whatever is left over after the manifolds is processed by the catalyst.

The secondary air injection reaction(AIR) system serves two purposes. It injects oxygen rich fresh air at the exhaust mainfolds on engine start up that reacts with HC and CO in the exhaust, especially helpful with richer cold start AFR. This helps to speed heating of both the manifolds and the catalyst. After a short warm up, the secondary air system diverter valve diverts air flow to the catalyst where it increases catalyst oxygen charge and reacts with left over HC and CO in the catalyst.

For lowest emissions, be sure that the AIR system is working correctly, both at cold start and at operating temp. You can verify this by checking for air flow on cold start at the hoses to the manifolds and at operating temp at the hose to the catalyst. We test catalyst efficiency on early systems(no catalyst monitor, post cat O2 sensor) by looking for significant reduction in exhaust emission after running the engine at 2,500 rpm for 30 seconds and returning to idle. We also test catalyst using an infared thermometer. A healthy cat should reach 700f at the outlet during the 2,500rpm cycle.

First make sure that the engine is running correctly(not lean or rich at idle no low compression cylinders) and that the emissions equipment is functioning. You just replaced the EGR valve. Make sure that there is no carbon holding the valve open at idle. Make sure that there is no vacuum at the EGR diaphram at idle. Then, you can further reduce HC emissions by retarding timing. Don't go crazy with this or you may cause an increase in both HC and CO and end up with the car you can't drive due to lack of acceleration. 2 degrees from spec makes a big difference. If the engine runs well enough, you can try 4 degrees retarded from spec. Be sure that the engine is fully warm at the test. If you get to sit in the car before the test. Keep the exhaust warm by holding the engine up at 1,500rpm for several seconds at a time, if you have to sit in line for an extended period.

When you set timing, be sure you follow the instructions on the emissions label. Don't worry about what the ECM does with timing. It will advance or retard timing according to its programming. Reducing base timing reduces the entire timing map since the ECM doesn't know where actual base timing is set. It only adds to the base setting.

mlbinseattle

This is basically what I said ... that HC's are unburnt gas.

I do believe I got my terminology backwards though ... I said advance the timing when I meant to say retard the timing. Basically, get the plug to fire before it reaches TDC. (I'm getting old. lol.)

ASE doc

Yes, the ignition event needs to take place before TDC. That is however due to flame front propagation, not because you want any combustion pressure against the piston as it rises at the end of the compression stroke. It is that type of pre-ignition that causes detonation and what is often called "pinging". Though most detonation is caused by hot spots or hot carbon deposits in the combustion chamber that cause the air fuel mixture to combust on compression, before the ignition event has a chance to form the flame front.

In the case of the 5.0TBI, and many other GM V8s of that era, the engineers put base timing at 0 degrees TDC and have all advance programmed into the ECM's timing map. If HC remains high after basic engine performance and all emissions equipment has been determined sound, retarding timing to 2 to 4 degrees ATDC will reduce HC. As I said though, if the engine runs poorly, aside from a certain loss of power due to late ignition which is to be expected with the timing set slow, then the timing may have to be moved back toward spec. I have had considerable success with just 2 degrees retard from spec, seeing about 100ppm reduction in HC. 4 degrees will give an even greater reduction and the engine SHOULD remain drivable.

It's easy for me to say, as a drivability specialist with a 5 gas analyzer sitting here in my shop, but in your shoes, I think I would prefer to verify passing numbers at an independent shop, before going in for emissions testing. Here at my shop the standard charge for scope check with adjustments is 1.2 hours, about $108 charge. Having said that, back when I didn't have a gas analyzer, I used to use the DEQ test center as my own personal gas machine. I'd run a car through, and if it didn't quite pass, I'd go around the corner do a tweak or two, and go back through. Now the test centers charge for the test, pass or not.

In California, the testing is performed at independent, state authorized shops rather than at state operated testing facilities. I'm not sure how that works. Here in Oregon, the testing center jockeys aren't allowed to give repair advice, only to refer drivers to a certified emissions repair specialist(good thing since the test centers don't employ trained auto technicians and would probably give alot of bad advice). I don't know how things are in VA.

Of course(and I never said this), once the test is successfully completed, you will want to put the timing back at factory spec. In fact, at the dealer level, we generally set base timing at 2 degrees BTDC on these engines and checked for detonation. 2 degrees added lead generally produces better drivability and performance, so long as there is no detonation.

ĦMR.AWESOME!

iTrader: (2)

Wow. Thanks, the both of you, for taking the time to thoroughly explain it all. I went in for the test today with the timing at 4BTDC and got wway high HCs and NO. One of the mechanics came up to me, asked me what I did and told em to do the opposite. Exactly as you said, doc. 1-2degrees ATDC. I did that, tested again and the HCs were just the same but the NO went back down to where it should be. Each test is $28 here so it's not too bad and I have been using the test as "my own personal gas machine".

When I got home today, I looked for home gas analyzers and was disappointed by my findings. I think looked up the price for a Tech1. Again, I was disappointed. Then I came across WinALDL. I wired up a cable real quick and plugged it in and I now have access to the SCAN data. Woohoo! (I am under the impression that this will help me do all of the proper diagnostic tests as described in the FSM)

The first things I noticed right away was that the TPS is -1.2% at idle. The voltages are within spec, however. Is this cause for concern? The other two pertinent things are that the 'Knock Count' was 11 and the 'Rich Flag' was going on and off; being 'on' 33% of the time.

Anything to say knowing that? I put the timing back to spec and will be going through the diagnostic procedures in the FSM to see what else I can learn.

Off topic: The car has more low-end power and carries it all the way up when the timing is ~4BTDC. I previously stated that I don't get any knocking, but I do occasionally get some under certain load situations.

ASE doc

I think the key to your issue is probably going to be in the AIR system. If the system isn't supplying sufficient air volume to the catalyst, HC will be higher than normal. I'm surprised that retarding timing didn't affect HC. I suspect that the engine(specifically the exhaust manifolds) wasn't allowed to fully warm up. As I said, it's exhaust manifold heat that is engineered to process HCs at the engine. If the AIR system isn't providing sufficient air volume to the manifolds during the warm up process, HC will be higher than normal after start up. Then again, emission testing needs to be done withthe engine at full operating temp only. The testing technician should know this.

5 gas analyzers are very expensive and require plenty of care also. I don't know if I would take a chance buying a used one either, since maintenance is often neglected are repair parts are expensive.
Winaldl is an inexpensive alternative to a professional scan tool. the issue I have seen with it is clarity of data. The data PIDS are sometimes hard to decipher due to poor clarification. The Tech1 was GM's factory tool but there are also aftermarket alternatives that do just as well. The Snap On MT2500 is a long obsolete but virtually indestructible scan tool with all the functionality of the Tech1. The "brick", as the old Snappy tool is commonly known, was discontinued in 2004 and is available used for about $300 on most ebay or Craigslist.

The exhaust rich/lean PID is simply a representation of O2 sensor voltage. It should constantly flash between rich and lean when the car is running in closed loop. Your 92 should have a heated O2 sensor(2, 3, or 4 wires) and should attain and remain in closed loop even at idle. Look at the sensor lead and determine whether it is heated by the number of wires. Non heated sensors have a single wire. If yours is heated as I think it would be, then observe O2 voltage with the engine at idle. It should toggle between .200 and .800 volts. If not, if it tends to hang low or high of .450, run the engine up to 2,500rpm and hold it there for 30 seconds. O2 voltage will go high with acceleration fuel pulses, then should level off and toggle rapidly between .200 and .800 volts. If it does not do as stated, suspect a faulty O2 sensor. Perform the test sequence for O2 sensor fault, code 13. If the O2 sensor performs as stated at 2,500 rpm, return the engine to idle. O2 voltage should drop low with decel fuel cutoff, then return to toggling. If it now toggles normally, suspect a faulty O2 heater or circuit. Verify 12 volts to the heater with the engine running, then test the heater for resistance. It should be in the 13-20 ohms range, higher with heat. If not, replace the O2 sensor. Because this sensor is so vital to correct operation of the fuel control system, if there is any question of its accuracy, replace it.

As I said before, HC is unburned fuel. It should be minimal coming from the cylinders to begin with. Any misfire at all will raise the content of HC. The manifolds are expected to process HC from the exhaust but if excessive HC is produced by the engine, it will be reflected at the tail pipe. One thing I didn't even think of until just now. You said you had you cat replaced two years ago. Was it replaced with a universal generic cat, perhaps at Midas or another corporate muffler shop? These cats are cheap and they are cheaply made. The precious metal load in them is low and quickly wears out.

What is CO during these tests? Is is higher than .5% or low like .05%. This could be an indication of rich or lean AFR. What are the standards for your vehicle. Here in Oregon they would be 1% CO and 220ppm HC. Oregon no longer tests for NOX. Is the test performed only at idle or do they use a dyn?

ĦMR.AWESOME!

iTrader: (2)

1) Tests were performed at full engine temp. I drove it around for awhile before going in and there was no one in line before me and I watched the inspector idle for about 5-10mins before starting the test.

The test is done on a dyno at 15mph and 25mph.

2) The 02 sensor is a single-wire, but the output is just as you described.

3) I replaced the cat myself with one from Advance Autoparts. So, yes, cheap.

4) CO limit is 0.22%@15mph and 0.32%@25pmh. The readings have usually been between 0.03-0.11%. When I was messing with the timing, the CO was up between 0.12-0.22%.

The only times my car has been close to passing the HC is when the car was cold. I dunno what that means.

Thanks for all the input. I'll work more at it this weekend at report back.

ASE doc

The CO is low which would indicate the system is on the lean side. Be sure that the O2 sensor is not leaning toward the rich side. This could indicate a faulty O2 sensor. Remember, too lean will raise HC. The low CO numbers make me question my own assertion that the AIR system could be faulty. The low CO would indicate that the catalyst is functioning well. Still, check the AIR system flow to be sure. I was thinking about contaminated oil too but that would also cause high CO.

Things to look at are coolant temp sensor, since you say the HCs are lower with the engine cold. If the coolant temp is reading a little high, it could cause the system to run slightly lean, which would result in low CO and high HC. Since this is TBI, look for any air leaks around the throttle body base. These engines did have trouble with the TB base gasket deteriorating and leaking at the corner closest to the EGR valve. There are two items on your ECM data list that you want to look at, Integrator and BLM or Block Learn. Integrator is GMs early version of short term fuel trim. Block Learn is long term fuel trim. These trim maps are a grid which centers around 128. Higher numbers indicate added fuel, the ECM is correcting for a lean condition. Numbers below 128 indicate a rich condition. Be aware too of fuel trim cell, or BLM cell(the WINALDL PID definitions may be slightly different. Fuel trim cells are just that. They are the different cells on the fuel trim VE(volumetric efficiency) grid through which the ECM's fuel MAP passes as the vehicle is driven through various engine speed and load conditions. The VE MAP is based on engine speed/load in the speed density(no MAF sensor) program.

Look for block learn to change low or high as the system moves from one cell to another. Since we know in what load and speed range the emissions test is performed, we can simulate this range on a road test while we monitor these data PIDs for clues to a fueling issue. It is very important in reducing HC emissions that the igntiion system is healthy as well. Any loss of power on one or more cylinders will raise HC emissions as unburned fuel is allowed to pass through the motor.

You just did a compression and the results look good. The white deposits you mentioned are oil ash. This is normal on an engine of this age. If they were heavy, they would point to excessive oil movement through the rings and/or valve guides. The compression readings you got tell me the rings are okay. Were all the plugs about even in color? If one or two were slightly darker or lighter, or if any have soot or carbon deposits, this points to a fuel imbalance or ignition fault.

The MAP sensor, TPS and ECT sensors are all vital in this system. The TPS isn't adjustable and if it had any glitches, you would have hesitation, so it is probably fine. The MAP sensor is connected to the base of the TB by a hard nylon tube with rubber ends. If either of the ends is weather checked and leaking, that can cause the MAP sensor to be inaccurate. I already talked about the ECT. You can check it first by looking for any corrosion at the connector. Then, watch the ECT PID as the engine warms up. An infared thermometer can be used to compare readings taken from below the T-stat housing to ECM ECT data. You can also watch for changes in block learn as engine temperature changes, once operating temp is reached. By this I mean to watch for changes as the engine cycles between 194 degrees and 224 degrees where the cooling fan comes on.

The injectors may also be restricted and cause the system to run lean. You can use a dial back, or digital advance timing light to watch injector output by dialing the advance back until the injector's spray shows in the light flash. This gives you kind of a stop motion view(strobe light) of the injector spray pattern. Look for any missing slices or any distortion of the cone. When you snap the throttle, the spray pattern should go wide so that it hits the sides of the throttle bore well above the butterflies and mists a little. If it seems weak, check fuel pressure with a gauge. Your 92 may have a test port on the pressure line just behind the TB. If not, you will have to remove the line from the TB to test pressure. Your numbers are so close anyway, pressure couldn't be off by much. You may get some improvement by running a fuel system cleaner through it.

Check the PCV valve for contamination. Good luck and keep us posted.

ASE doc

Be sure that there isn't an air leak at the EGR gasket.

ĦMR.AWESOME!

iTrader: (2)

Plugs were all even with just a little white ash on them.

MAP and connections are all good. IAT is good. TPS is indeed fine. Fuel pressure is good. AIR system works as it should.

The 'timing-chain-like' noise I described earlier is actually coming from the new PCV valve.

I found that the new EGR valve wasn't holding vacuum like it should. I installed a new, better one.

The PCV intake tube had some oily dirt around the base so I checked the vacuum at the dipstick tube while blocking off teh intake tube. Vacuum was ~1"Hg. I replaced the intake tube gasket and then the vacuum went up to ~2.5"Hg. Is this ok or is air getting into the engine where it's not supposed to? The manual just says there should be vacuum without giving any numbers.

Engine coolant temperature sensor is good when the engine is cold. It reads about 20degrees lower than the gauge in the instrument cluster. I think this is fine, though, as the manual says the normal range is 190-210 which is what I'm getting.
When I first bought the car, the coolant fan would only come on with the AC. I replaced the fan switch and it's connector, but the problem persisted. I gave up and bought a fan relay that has the probe you stick into the radiator. That has worked just fine for many years now. I doubt it's relevant since it's its own circuit.

I will look for air leaks another day, once I figure out the best way to do so.

I need to borrow a fancy dancy timing light from someone to check the injectors.

Can anyone tell me what the vacuum line sticking straight up out of the intake manifold by the distributor is? The line attaches to a metal piece that screws in to the intake manifold. I can't find anything about it in the manual. I get a poor idle when i disconnect it.

sofakingdom

iTrader: (1)

The "manual" tells you all about the vacuum stuff that's part of the engine; sensors, evaporative stuff, etc.

However, the car also uses vacuum to power various accessories that are NOT part of "the engine", but rather, part of the chassis, separate from the engine. Kinda like, if you could go look up a "manual" for your house that shows the wiring, it might show all the receptacles, but wouldn't show what's plugged into them, because that stuff isn't part of "the house". Same deal here.

That feed typically goes to the HVAC system and the cruise control; both separate systems that are totally discrete packages, installed apart from "the engine".

I'd suggest, rather than whatever "check" you want to do to the injectors, that you simply take em apart, soak all the parts in lacquer thinner for a few hours, and put em back together with a new paper & rubber kit. Best way to "check" em is make em work like new again.

ASE doc

Vacuum at the dipstick, or at the PCV make up air tube, with the PCV valve installed, is more a test of ring seal than anything else. Yes it also checks for clogged passages in the PCV system, but if there is no vacuum, or pressure in the crankcase, the first thing I would suspect is excessive blowby past the rings. The PCV valve rattling is not unusual and doesn't necessarily point to an issue. Sofa is correct that the vertical vacuum line behind the TB is most likely to accessories, such as cruise and HVAC. Be aware though that these can still be the source of unmetered air. Any unmetered air will cause a lean idle, and thus raised HC.

There are two types of EGR valves. Negative pressure modulated and positive pressure modulated. I honestly can never remember which one is which without looking it up, though if I remember correctly, your car should have a negative pressure modulated EGR. One of the two will not hold vacuum unless there is pressure or vacuum applied to the exhaust port of the valve. Therefore, testing the EGR by applying vacuum is not a valid test of the EGR, unless the service manual specifically instructs you to. Even then, I would want to be really sure what EGR I'm dealing with before I condemn one.

Sofa's also correct that my injector test is kind of a PITA. Not a big deal for me since my timing light is handy. In your case, you may be best off just cleaning them, now that you know pressure is okay. I personally would use an injector cleaning service, where they can sonic clean and flow test them. For TBI, there are only 2 per car so the cost is not too bad. Any increase you get in inlet vacuum is a good thing. I don't know what intake air tube gasket you mean.

Be careful running the coolant temp too low. The OE thermostat only opens at 194f and is most important part of managing coolant temp, but the fan on temp also has alot to do with it, once the T-stat is open. OE fan on temp is around 229, which works out to about 3/4 gauge on most cars. The reason for running these engines so hot is to improve combustion efficiency, which in turn lowers emissions, including HC.

ĦMR.AWESOME!

iTrader: (2)

I see. HVAC vacuum source seems to be what it is.

I am positive that the EGR is negative backpressure. The original had an N stamped on it. The first new one did not specify which type it was. The new new one is specified as the negative type.

I have been running the coolant temp to spec, there is just some disparity between the WINALDL ETC reading and the gauge in the cluster.

Cleaning out/rebuilding stuff sounds like the way to go.

The 'gasket' that I was referring to is the rubber seal that fits into the valve cover and then the PCV inlet tube is inserted into the gasket.

Do the dip stick vacuum readings indicate that there may be a problem somewhere or is 2.5"Hg fine?

The cruise control has been disconnected since I got the car so there may be some unmetered air there. I will be checking the accessory vacuum lines.

Thanks, again guys (especially doc). You're really helping me out.

ASE doc

So you mean the make up air/valve cover grommet. I just wasn't sure. As I said, a slight vacuum in the crankcase is normal. In fact it's a sign of a healthy engine. We already knew your engine was healthy by your compression readings. If crankcase vacuum was higher, I would check the make up air circuit to be sure it is clear to the inlet air tube or air cleaner. It is also possible to have an intake vacuum leak to the crankcase but you would also have an idle misfire.

Since your speed control is inop, disconnect the vacuum source to it. The vacuum source for CC goes to a switch at the brake pedal lever. I believe, if my memory serves me, that this switch vents vacuum when the pedal is depressed. This wouldn't affect normal running vacuum, with pedal not depressed. Still, it is one possible leak to eliminate.

86LG4Bird

iTrader: (1)

That's normal. Data and cluster readings are taken from separate locations.

ĦMR.AWESOME!

iTrader: (2)

Another update.

The cruise control vacuum source had already been disconnected. In order to check for any leak in the HVAC/other vacuum lines I disconnected the vacuum line from the source and capped it before doing another datalogged 25mph test run. There was no change in the numbers.

I sprayed throttle body cleaner around to test for leaks and found a little one on the EGR gasket. I fixed that and ran the 25mpg test again. BLM was down a bit on subsequent test runs. BLM no longer goes above 140.

The intake gasket seems to have no leaks, but I want to check around a bit more.

I put seafoam through the PCV vacuum line. Good amount of white smoke but no change in numbers or feel.

I did the 25mph test first thing this morning while the engine was cold and the BLM stayed at 127. The test ended with coolant temp at 147F. I did another run with the coolant starting at 160F and the BLM went back to it's normal high-ish numbers. Does this point to a vacuum leak? This may also explain the 2 times when a test was done, I barely failed, the test was done again within a half hour and I failed miserably. The car was cold for the first tests.

The logged data from WinALDL shows that, usually, the 02 sensor stays under 0.01 for 10-40s doing the 25mph tests. Code 44 sets if it stays that low for 50s, so I'd like to try the test on a longer stretch of road. A code has never been set while doing the emissions test, but I don't know for how long the inspectors run the test.

I checked the cat converter with an IR thermometer and the inlet temp was 350F while the outlet temp was 200F. That can't isn't working, right?

I noticed that the month-old coolant in my overflow tank was brownish and I see a bubble in the coolant appear here and there. The coolant in the radiator is not brown. When I look remove the rad cap and look down into the radiator, there are a lot of bubbles. I need to recheck and confirm this, though. I rented a block tester, but it came back negative for combustion by-products in the coolant. I compression tested the coolant system and found some leaks. Could a leaky system cause discoloration as well as bubbles? The coolant doesn't particularly smell like exhaust, fuel or oil. It also doesn't smell like fresh coolant, either.

I will pull the new 02 sensor tomorrow to look for any deposits. I pulled one of the new plugs today and it had a bit of the white deposit that the old ones had. The white is only on the insulator and only on the side opposite the ground electrode.

Any idea what kind of pressure the AIR pump should provide? Mine pumps, but I'm not sure if it could be too weak or be moving too little air.

I'm still at it.

ĦMR.AWESOME!

iTrader: (2)

I put the car in neutral and kept RPMs at 2000 for one minute. The 02 sensor switched between 0.031 and 0.035V for 61s while the tps was constant. The engine stayed in closed loop and no error code was set. Code 44 is supposed to set when the 02 reads less than 0.25V for 50s while in closed loop. So what gives?

Ima check for exhaust leaks tomorrow using a fog machine. It's water/glycol based. I dunno if it's as healthy for the engine as mineral oil. I didn't find anything conclusive in my research.

02 sensor looked fine, btw. It just had a bit of soot around the base.

I also want to mention that at idle and with fluctuating throttle position, the 02 readings swing all over the place, as they should.

I found another vacuum leak at the accessories/HVAC source. I fixed it. Engine idles a tad smoother. Ran the 25mph test, but numbers are the same.

ASE doc

What is integrator doing when O2 voltage is hanging below .450? It should be steadily rising until O2 voltage begins to toggle above and below .450. Closed loop means that fuel correction is active. Integrator should be moving to correct for a lean condition and block learn should rise as needed to keep integrator centered around 128.

The O2 sensor needs to toggle between .200 and .800 at 2,000 rpm. The early systems were more primitive and didn't set a code for low activity, only for low or high voltage. That's why your system only sets a code if it runs below .25 for any length of time. If your O2 voltage is hanging below .450, you still have problem. This could be caused by a failing O2 sensor, but with high HC emissions, I'm gonna bet that your engine is just running lean. The reason it runs more lean in the 25mph test is because the engine wants more fuel under load than sitting at 2,000 rpm in the service bay.

The test for correct O2 sensor response is to alternately add fuel, and then air. First, since your system is reading lean, try injecting a small amount of propane into the inlet air stream. Go easy so not to stall the engine. O2 voltage should rise in response to the added fuel. Slowly increase propane until you can hear the engine loading up with fuel. The O2 should read close to 1 volt at that point. If it still won't go over .450, the O2 sensor is no good. If it does respond as I think it will, you still have either unmetered air, or you need to address your injectors. To add air, you would disconnect a vacuum line from manifold vacuum. Your engine is already running lean so this probably isn't necessary.

ĦMR.AWESOME!

iTrader: (2)

The integrator doesn't do much. It pretty much stays at 128.

I want to reiterate that Code 44 does NOT set even though the conditions for it ARE met. I don't understand that.

The car was cold and I started it up. I began logging data ~30s after starting. I then drove to the place to do the 25MPH test and did a bunch of runs. After that I drove around at higher speeds for a bit. I cleaned up the data a bit and you can see the log here. Anything you can see? Assuming you have the time to look. If not, I don't blame you.

In order to check for exhaust leaks, I plugged up the tail pipes and disconnected one of the AIR check valves and connect shop air to it. I set the regulator to a few psi and let her rip. I did this test while the engine was cold as well as hot. I found only two small leaks. One at the AIR injection point on the catalytic converter and another at the clamp connection to the piece of exhaust that goes over the rear axle. I do not think these are the cause of my problems.

I don't have any propane lying around but I do have a little butane torch. I tried the test you described but I don't think the torch has enough flow to cause a change in combustion. Either that, or butane doesn't burn in an engine. I used carb cleaner and the 02 readings went up to 0.99-1.00.

sofakingdom

iTrader: (1)

How did renewing the injectors do for ya? Usually makes a TBI run like brand new.

ĦMR.AWESOME!

iTrader: (2)

I haven't done that yet and was actually just looking in to the best way to do that. Some people say soak them in carb cleaner. Others say don't. You got any opinions? Took apart, cleaned and put new gaskets and stuff on the whole tbi unit a few years ago, but I didn't do anything with the injectors themselves.

sofakingdom

iTrader: (1)

No particular opinions at this point.

ĦMR.AWESOME!

iTrader: (2)

Ha. Oops. I am soaking the injectors presently and will leave them until tomorrow. Then I'll put 'em back together and do another test run. After soaking them for a bit, I submerged them in lacquer thinner and then put a 9V battery to the terminals a bunch of times to try and get as much solvent in there as possible. Btw, the lacquer can isn't lying. That stuff is extremely flammable.

camarito

i couldn't get mine too pass either i tried 5 times then a friend told me to mix 1 gallon of denatured alcohol with 10 gallons of regular gas, i did it and it passed with flying colors.
I also wrapped the cat too keep it hot and more efficient since is far away from the engine.
this is a carbureted engine with nothing more smoog stuf than a magnaflow cat

ĦMR.AWESOME!

iTrader: (2)

I put the injectors back in and the engine idles and drives much more smoothly. I did the 25mph test and the BLM still goes up in the 130s while the 02 has long periods of sub 0.05V.

I'm thinking there is a vacuum leak somewhere that only occurs when the engine is warm and only causes problems while at sustained RPMs.

Camarito: I'll keep that trick in mind. I may have to resort to some sort of quick fix, but I would like to find out what is wrong first. This is fun for me so I'll keep at it as long as it stays that way. Once it gets annoying, I'll try your method.

ASE doc

The system is going into closed loop fairly normal. I see that as the system gopes closed loop, that Int is responding normally, with BLM close behind. From looking at your data at speed, I would say that the problem doesn't appear to be fuel system related. If it were, we would see higher INT and BLM at higher MAP value, where more fuel is needed. What were your exhaust gas readings on this test run? Does HC go higher at idle and come down as the vehicle accelerates to 25mph? Is HC lower at cruise? It should be lower as the manifolds heat up anyway, but according to your datalog, there is plenty of fuel, so HC should be low.

Recognize of course that as the engine accelerates, especially as you open the throttle, there is additional fuel injected to compensate for sudden manifold pressure rise. This additional fuel will cause an instant increase in both CO and HC. This increase will show on the gas machine for as long as it takes for the system to level off at cruise. HC will also spike when the throttle is closed and fuel that is caught in the manifold runners gets through the engine. The tester has to be aware of this normal behavior and take it into account in the readings.

When Oregon used wheel dyns for emissions testing, they would run the vehicle from idle to 30MPH and back. But they only used light throttle to simulate normal driving. Lighter throttle movements are going to produce less spikes of CO and HC.

I see at one point, with the coolant temp at 211 degrees and MAP at 98.5 Kpa, O2 voltage was .968, with INT and BLM both at 128. That is perfectly normal hard throttle acceleration fuel delivery. If O2 were lower, or INT/BLM were higher, I would suspect a fueling issue either caused by low fuel pressure or wimpy injectors. The high BLM at lower MAP values would seem to indicate un-metered air. However, since the O2 sensor is god in closed loop operation, an inaccurate sensor can also cause false fuel trim correction. If you don't know how old the sensor is, or if it's older than 60K mi, it wouldn't be a bad call to replace it just for drill.

Does this engine run smooth? It could have a failed intake gasket affecting just one or two cylinders. We used to have more trouble with the factory aluminum manifolds equipped with EGR. The manifold warps and causes the gasket to fail between runners 4 and 6. This creates an cross leak to the exhaust crossover and sometimes to the crankcase. It would show as a rough idle, misfire on two cylinders. I also see that the high points of BLM do gradually rise with coolant temp. This could point to an inaccurate CTS. You may want to pull the sensor and check it for scale deposits that may be affecting its accuracy. If you run green coolant, dump it, flush the system and replace it with the new Prestone Core Guard Extended Life coolant. It is the best coolant for your engine.

ASE doc

Have you resolved the issue? I would like to hear back on what you found.

ĦMR.AWESOME!

iTrader: (2)

Sorry for my absence. I went out to SEMA and then had mucho work to do when I got back. I'm gonna get working on it again in a few minutes.