Ok I need some help figuring out why I failed the pre test. Every place I talk to wants to charge me $150 and keep the car for 2 days to run diags.

The place I went seem a bit shaddy. Normally when I take a smog test they do one run at 15MPH at 2500RPM and one at 25MPH at about 2500RPM. This place did one at 15MPH at 1710RPM and one run at25 at 1761RPM.

They also told me that the timing was fine, but for some reason did not point out the fact that it is running at 13 BTDC. In fact when he checked the timming he connected the wire to wrong side of the engine. #1 piston is on the forward pass side. He connected it to the forward driver side.

Conveinetly they just had a 1992 Camaro RS 3.1L in the other day that failed. Then proceaded to tell me how hard these enginges are to work on. I never told the jerk I do most of my engine work my self! Well any ways here's the numbers.

First run
15MPH @ 1710RPM MAX HC = 112 My HC= 151 MAX CO= 0.72 my CO= 0.53 MAX NO= 778 My NO= 1706

secound run
25MPH @ 1761RPM MAX HC= 86 MY HC 129 MAX CO= 0.60 MY CO= 0.43 MAX NO= 717 MY NO= 1494

CO2% and O2% on both runs were 12.50 and 2.89

small back ground on the car.

I never had a problem pass the SMOG test before. every time it passed with numbers so low that if I was smoking near the bay I was told to either put my smoke out or step away becuase it was messing with the readings.

Plug wires were replaced a couple of weeks ago. plugs haven't been touch for a while. O2 sensor has only been on for about 15,000 miles. Cap and rotor were replaced about 1 - 2 months ago. EGR is function fine. No SES light, yes I comfirmed that it does work.

I was hopping that some one can give me an idea of what is causing the high numbers. BTW I'm in North Cali.

 

Change your Catalitic Convertor- its bad with that high of HC readings ( they normally wear out after about 6-8 years). Change your plugs and change your oil then smog it again- you should then pass no problem.

 

Could also try one of those catalytic-convertor-cleaning additives... in fact I think that's what "Guaranteed to Pass" is... that's what I dump into my car before the smog test; $6 at Pep Boys.

Could also be that you're running lean; that's indicated by the high HC but normal CO. HC's mean incomplete combustion... can be caused by a misfire, timing, and if your a/f mix is too lean, you won't burn all the gas in the cylinder. (Someone argued with me on here about it; it does seems backwards yeah but if you do an internet search on it...) If your CO was high you'd be running rich, and the solution is to just change the air filter for a new one.

The pickup on the #2 plug wire shouldn't matter -that- much; unless he was using a timing light on your car. The balancer mark wouldn't line up close to stock timing, and he'd botch the whole car by trying to set the timing from the #2 cylinder. If he was just using the pickup for his smog computer to "read" engine RPM, it's okay.

You might want to check that the balancer hasn't slipped, and that the timing mark of the balancer lines up at the 0 degree mark of the timing scale, when the #1 cylinder is at TDC of the compression stroke. If the balancer slipped, you might really be running at 18 degrees advanced. Definately set it back to stock (10 degrees) for the test!

NOx's suck... they're caused by high temperature and high compression- sorta what happens inside a combustion chamber! You might need to de-carbon your combustion chamber; either with the water-mist method that I mentioned or the "GM Top Engine Cleaner" method that AGood2.8 mentioned a few days ago. Check your cylinders with a compression gauge to see if the numbers are way too high.

NOx's are also cleaned up by a 3-way cat, so it could go back to AGood's idea of a bad cat. (Didn't our cars get 2-way cats, though?) EGR also drops NOx, but I don't think your road speed was high enough, or the engine rpm was low enough, for EGR to have kicked in. (Both situations have to occur for EGR to turn on.)

If they thought a 2.8/3.1 F-body was hard to work on, they must sht themselves when they have to work on a 350 TPI f-body.

 

egr is plugged.clean it and install a nice fresh GM o2 sensor.

 

I don't belive the cat is bad it is only 1 - 1 and 1/2 years old. The only reason I replaced it was to put a Catco high flow on there.

I think I will go after the plugs, oil, and timming. Plus I think I will take it into a station near my work on Monday. I live in the Central valley, but work in the Silicone Valley. The Central Valley has enhanced SMOG check (SMOG II) While the silicone valley is still using the standard SMOG test. This shouldn't matter as long as the test is done in Calli.

He was useing the timing light on the #2 plug, but had the pick up for the smog machine on the #1 plug. Just seemed backwards as all hell to me.


Thanks for the replies. I don't feel like shelling out $150 for someone to tell my plugs are messed up!!

 

First ya gotta find a fair smog station.
Ask around!
OUT in LA, CROOKS ALL OVER!

Next yep, new plugs, new oil, fresh preminum gas, remove the air filters before ya enter the smog station engine bay.
Yes, 1710 at 25 MPH is right (torque convertor lock up at 3rd gear).
WHAT THEY DO IS
Run the car real high in idle speed, then TOTALLY LIFT FOOT OFF THE GAS PEDAL, loading up the emissions that "are to be burnt".
Due to "age", worn/weak stuff, ya fail due to high amounts of unburnt emissions at a low idle speed.
Bastards.
Finally found fair smog guy in LA & I drive like now over 25 miles for their approval at smog time (see the 1985 3.4 powered Firebird as my example of easy smog passing rides-'85 3.4 powered Blazer will be visiting soon, too!)

 

Karl,

I don't have a TC to lock up, 5 speed stick. I would like to know how he got it run at 1761RPm at 25MPH. I can't even duplicate that on the road. It is to low of an RPM and the engine lugs like there is no tomarrow.

Either today at lunch or tomarrow I will be taking it done for another test in Santa Clara were they still don't have smog II. Should pass with no problems. I cange the plugs, cleaned the EGR valve, and set the timming to 10BTDC.

 

Now ya mentioned a stick set up & Yes I totally see your point
Let us know how well ya do this time!
Ya should pass easier now!

 

I don't think that it matters where you get the car smogged. It has to be at the same standards as the smog laws of the area where the car is registered. I live in L.A. where they runthe BAR-97 smog test on the dyno to check for NOX. I can't drive my car down to Palm Springs where they still do the old BAR-90/2 speed idle test because the state computer will not accept the certificate because of where I live. So getting your smog check somewhere else won't be worth it. Chances are though that when they start to test the car, they'll run the same BAR-97 test that you get in the Silicone Valley because they are so close together they are under the same machine rules.

 

Yeah i thought they might have a way to keep you from subverting the system, DAM! Oh well.

I think I found some thing that may be a contributing to the problem. My #5 injector has not been spraying enough fuel. When I pull the plugs you can tell that one piston is running lean as hell. It's done it ever sence I had the car , a little over 4 years now. It's never given me a problem with passing the test before, but I think I will get that taken care of before I go for another test.

the injectors also seems to be the cause a of a miss fire that has only gotten worse, I never been able to resolve the missfire. Went after every thing, vaccum lines, rebuilt distributor, etc. I will definetly let you guys now the next test goes. mabye in the next week or 2.

 

Don't knwo if ya got your car fixed, you havn't said anything about it, but I figured out how they got your RPM's lower than you run on the street. Think about what gear you cruise in, then think about the next gear. For a long time when my car was running crappy, going 40 I had to stay in 4th gear and keep it at 2000 rpm to have a decent amount of power if I needed to step on the gas or something, the car just wouldn't run well under 2000 rpm. Now that my car is running well again, I cruise in 5th at 1500 rpm, gives me better milage on the streets. I bet they ran one higher gear than you do at the same speed, that's all. Let us know how your car did. I finally got mine to pass...

 

Diffrent things can be happening here. H/C is a by product of bad combustion. Miss fire , leaness especially but it will also follow C/O. Egr not responding due to the RPM dropping off could cause NOx problems. Nox is a byproduct of extreme cumbustion temp's however Carbon Monoxide is high indication a bad cat and with as much C/O as your posting Nox is actually higher than I would expext with a good Cat. Almost never see a richer mixture followed by high Nox. O2 is also high, indicates to me that the cats not igniting the air and unburnt fuel. Nox bed is in the cat... My analysis with out looking at the car would be Cat. a temp test of the cat warm should be like 300 degress in the front inlet of the cat and 400 in the rear outlet area.

 

As far as the gearing goes you were right. I played with were I shift and as able to ge the numbers to match. Never did 25 in third gear before. Normally I shift into third at around 30MPH. It's runs fine at 25MPH in third, just gutless as hell if I need to hit it.

Changed my plugs and was going to take it down for another pretest at a different test station that had newer equipment and all they do is smog test. I showed the numbers to the guy before the test was run and he said he wouldn't advise running another pretest untill I get the EGR and O2 sensor replaced. It would just be a waste of money. So I spent most of Saturday running around looking for a good EGR valve in the scrap yards. These dam digital EGR's are to expensive to buy brand new!!!. Finally found one. Replaced it and the O2 sensor and toke it down for a regular test.

The test aborted becuase the car over heated. This accualy turned out to be a good thing belive it or not. As I was talking to the guy he told me that if the car is over heating the NOx will go way to high and you will suffer mild pinging. Which causes the HC's to go up due to the uncomplete burn. Told me to replace my stat and see if the car is still over heating.


This is ware my new problem comes in. I never new the car was over heating. The temp gauge never went to the over heating point. It would get close in city traffic, but never all the way. On the highway the temp stays low due to the increased air flow.

I replaced my stat for ****s and gigles, and it was cheap (just spent $75 on a used EGR). drove it around at about 25MPH to get it to heat up and found that my temp reading is erratic, It will go up some and then drop quikly. It would do this a couple of times before it goes up and stays up. My thoughts are that the temp sensor and possibly the fan switch are faulty.

The fan seems to be kicking in to late. I had the car idling in the drive way. While I watched the temp gauge I had my wife tell me when the fan started. It would start just before the 260 degree mark. Once the fan started it would cool the engine down to a little below 220 but would start the same cycle over again. Go up to the 260 mark and drop back down.

My question is should I replace both the temp sensor and the fan switch. Or which one should I suspect is bugger that is causing the problem. When I have the Air on the fan is turned the air presure sensor. So in city traffic the temp stays bellow 220, but the nedele stills does it jumping thing. If I knew the car was over heating I would have fixed this a long time ago.

I have more faith in this smog shop, becuase the guy sounds like he knows what he is talking about and did every thing he could to get the car to cool off. He even brought out a big old fan and put it in front of the car.

I have a hard tiem beliving the cat is bad. It is only about a year old. I will see if I can pick up one of those IR temp sensors so i can check the temp of the inlet and outlet.

Car info.

1992 Camaro RS 3.1L
So far replaced cap and rotor, plug wires, plugs, EGR, O2 Sensor. Oil and stuf get replaced at thier proper time.

Only mods are mild bolt ons, Cat back, coil, etc.

Thanks!!

 

Snap On has this nifty hand held "reader" that tells ya exactly sensor wise, what's happening.
Plugs into the ALDL & ya drive to observe readings. You scroll down to read all details reported on screen.
I had my 1985 scoped out this way.
While the car was sitting in the drive way I saw these readings (I have idiot light dash, still).
My fan kicked on at 220*, shut off at 200*.
When I did the swap I needed to replace the fan sensor due to breaking it. Cost me about $22+ at dealer. Yes the one in the back by firewall. I replaced it with engine out of car. The front one by AC Compressor, I removed & bench grinder polished copper probe & reused.
What has happened is that your system has lots of corossion/dirt in it.
This has coated sensors.
I would also suspect that a ground is not very good, thus your erratic readings.
What to do.
Have you also replaced the timing chain yet?
Fresh Fluids?
Good thing is you know your cooling system works, it needs a very good tune up and some wire tracing for more secure grounds & connections.

 

I'll have to see how much that little toy cost!

Timing chain and water pump were changed back in Sept. of 2002. Radiator and hose were changed back in Aug. of 2002 due to it spliting a seam.

I think I'm just going to replace both sensors and see how it works. If the nedele still jumps around I will trace the wires. I have a feeling the sensors are just shoot to hell and back. I have 245,000 miles on this engine and the sensors have never been replaced. So I think they have just given up the ghost.

It may be time for a full distributor rebuild. If I can pass the Smog after getting the cooling isue under controll I will rebuild it.

 

I was able to remove my sensors (except the broken one-replaced), clean & reinsert.
Problem is the angle, effort & access of back one.
Front ya move the AC Compresor for access.
MAYBE power steering pump, too
I believe the sensors are 17mm heads
I'd check wiring first (easy!)
Rebuild distb next.
Way easier than accessing those sensors right now.
That Snap On tool is about $1,000
BECAUSE
it is updatable (with chips/cards of specific rides)
Portable
Has different plugs for the "ALDL" of other rides.
Ya pay to have it used on your ride

 

On the 3.1L the temp sending unit is next to the AC unit, but there looks there is enough room to ge to it with out moving any thing. The coolant temp sensors is located near the water outlet in the fron of the intake manifold, and fortunetly there is plenty of room to get to it. I might do this during the week due to the fact that I am having to use the AC to turn the fan on more and more. mabye I'm just paying more attention now that I know there is a problem.

I live 88 miles away from work so most of the time I am out of energy to work on the car. Plus it is dam hot when I pull into the drive way. SO I save most of the car work for the weekend if I can. But I will let you guys know how it turns out. I never thought a cooling problem would screw with the smog test!

 

you talking about a Snap on scanner ? .. I have one, they are about 1400.00

 

That is EXACTLY what my friend used for my example.
It's so cool!
Literally shows all sensor processing information way faster than the 1985 ECM.
Yet $1400 for a "digital dash" is pricey.
Can't beat the hook-up, tho.
Wish I could swap in my gauge dash package as easy as that scanner!

 

The ECT in the manifold takes a deepwell 19mm socket, swivel, and extension, and ractchet. Undo the throttle cable and your in!!

I would also replace the guage sensor, which is in the left head, right above the power steering. It is cheaper then the ECT. It is larger then 19mm, more like 22 or something?? Its a pita, but might be bad also.

I noticed the fan on mine didnt spin very fast, then went out. I would check to see how fast your fan spins. If its not spinning enough, it wont cool the system down fast enough.

 

To bad it costs so much. If I had $1400 for a tool I would have a fourth gen!

The fan should be fine. If I turn the fan on by turning the AC on the egine cools down quickly. So I think I need to replace the fan relay along with the gauge sensor and the ECT. It seems to have gotten worse. This morning I was stuck in traffic and asn't able to watch the gauge, but my wife leaned over said "hey look how hot the car is". When I looked down it was just starting to hit the red zone. After I pulled over to see if fan was on and it wasn't. So I will have to keep an eye on it and use the AC to keep the car cool untill this saturday when I have time to fix it. As long as I have a work around till this saturday it's not a major problem.

What function does the ECT serve? IF the gauge sensor tells the gauge the temp of the engine why would a second sensor be needed?

 

The ect tells the ecm the temp of the engine. The ecm turns your fan on. IMO, sounds like ect is bad, or your ecm is bad. I belive the ac relay to fan is the same relay (if you udnerstand my babble)

Then the sensor in the head goes to your guage, and only your guage.

As to why to sensors, ask gm. But camaros are not the only ones this way. All gms are.

 

Ok good news and bad news... Bad news first i didn't pass the test. Good news my numbers were lower this time (see bellow)

That friggin fan is pissing me off big time. Replaced both sensors and the fan relay and yet the fan still does not come on at the Correct time. After yelling at the car and dam near trading it in for the fourth gen I have been looking at I riged a switch to turn the fan on. This seems to keep the temp under controll.

Any ideas? The ECM is only about 1 year old. Same with the radiator and the cat.

Number time...

15MPH run.

HC= 141 Max 112 NO= 664 Max 778 (much better than last time.)

25MPH run.

HC= 98 Max 86 NO= 509 Max 717 (Also much better than last time.)

I am all most due for an oil change. The guy told me that becuase I drive so much I might be able to pass by doing another tune up and oil change. This time my timming came in at 9 BTDC .

 

I'LL BET SOMEONE STUCK IN THE WRONG RANGE PLUG!
GET A HOTTER PLUG TO COMPLETE BURN MORE IN THE CYLINDER!

 

man that cali emissions sound horrible. i had a blazer running on 5 clyinders burning oil too pass in ohio.

 

what you could do is right before you go to take the test, pull the connector off a couple of injectors. When I had a cracked valve, I pulled the wire off the dead cylinder to save on gas. It'll cut down on the amount of gas entering the system, but make the car run rough. It doesn't throw a code either. Make sure you put it back on right after. worth a shot, kinda ghetto, but it might work.

 

man that cali emissions sound horrible. i had a blazer running on 5 clyinders burning oil too pass in ohio.

I moved to California in Dec 1980.
During the first year here, I couldn't see two blocks down the street, some days, due to smog.
It was cars like yours that caused teh problem.
Multiple cars like that.
PLUS, take your pick of whatever else.
End result, smog was really bad.
I got pollution sick.
Fast forward to the present.
I now live in the San Fernando Valley, once so polluted I couldn't see more than two blocks down the street.

When you have a child, you'll appreciate the progress actually seen & made.

PS I recently turned in a gross polluter.
I was happy to do it.
Why should he get away with not followig the law for the better of all of us?

My 3.4 Firebird goes for it's second swapped CA smog test shortly.
No worry at all, as I followed the rules & also ending up going faster.
I worked very hard to do my Firebird 3.4 swap correct. As I also have for my Blazer 3.4.

Fix your car or dump the engine for the kids growing up.

 

I stand by Karl on this one! Reducing the amount bad gas that comes out of cars is important. This is even more important in a high population area. All though the smog can make for a pretty sunset once in a while. Go figure.

I have no idea which range of plugs I currently have I just tell the parts I need plugs and the specs on the car. Unfortunetly I don't have time to do any work during the week so the tuneup will have to happen early next saturday as I am out of funds this week due to getting rear ended and have to shell out a boat load of money to get my back in order. It was low speed, but I didn't see it coming and I wipped like a rag doll. Fortunetly there is very little damage to the car.

I could have fried another spark plug wire again. the pas. side of the engine is a hell hole for plug wires. To much high temp crap shoved into to little of a space. Mainly the dam EGR stalk and it's heat shiled. The middle and front wire end up fried on a regular basis. I keep spares on hand in the car so i do emergency road side wire changes. I noticed that if one plugs drops out I can barley get the car up to 50MPH. I have to change those 2 wires about every 2 - 3 months. I put about 50K miles on the car a year. So that comes out to about every 6K - 9K miles.

I will do the tuneup and see what happens.

 

#3 plug boot (middle plug wire on pass. side of car) is prone for heat damage because of the EGR- I have run Taylor's 1200*fire boot sleeves for years now and have resolved that problem. They are worth the $50 instead of buying new plug wires every 6 months.

I too have no problem with cleaner emissions.
The part I have the problem with when it comes to Calif. smog checks is the visual inspection B.S.- Its a money game- Just put the friggin sniffer into the exhaust tailpipe and read what comes out WITHOUT opening the hood- If it burns clean then leave us the **** alone!

G()d damn California bureaucrates need to go ahead with the so called "fat tax"- That'll hit fat *** Rob Reiner back in the pocketbook and then we'll see how much a hippocrate that fat bastard is (To all that don't know- He's the leading front that started the higher cigarette tax and smoking ban in resturants here in So.cal- its a money game.(p.s.-I don't smoke but am not going to sit around and wait till they tax something I do like)

Sorry for my rant- Its a bad subject for us car buffs here.

 

Well emisions will have to wait for a while. My Camaro cought fire last night on the way home. Not sure exactly what happened, but it looks like the wire that runs from the battery to the Alt had a split boot and started to ground out to the bracket. This in turn caused the wire to burst into flames. Scared the crap out of me.

Fortunately I had a fire extinguisher!!! It only gave a short burst then died, but it was enough to put the fire out. Damage was kept a minimum and is fixable. So for now I get to drive my 1968 Ford F100.


DAMM!!!!

 

Ok fire damage is fixed and next Sat. I will be doing a full tune up and see if I pass the test. Fortunetly there turned out to be less damage then I thought. It only cost me $15 in parts about the better half of the day to repair. The Alt. got fried by the fire, but I had a spare. The scrap yard had only one car I could pull the wires from and it had every one I needed. Lucky day for me!!!

I was worried that maybe the ECM got fried, but there doesn't seem to be a problem there.


I'm still having problems with the temp gauge, and the fact that the fan does not turn on at the correct time. I have a temp solution for the problems in the form of a switch. after the car warms I flip the switch and everything is fine. Just can't forget to flip the switch.

The gauge is acting funky. after it reachs the middle point (220deg) it will 20 - 40 degrees in less then a secound. then will drop 10 - 20 degrees just as fast. So i have no clue what the temp is. I'm thinking it is a electrical problem, but not sure ware to start. Any time the RPM's drop the temp will also drop a little, but the drop is to fast for it to be a normal cooling down of the engine. If the turn signal is on the temp gauge will bounce 5 -10 degrees alogn with each blink of the turn signal.

What would keep the fan from turning on? I replaced the sensor and the fan relay, but still no go. I don't really suspect the ECM. I replaced it about a year and a half ago. Will a parts store the ECM. If not how can I get it tested? I would really hate to have to replace the ECM again, but if that will solve the problem I will.

It has been a good car it is just screaming "help me!!!"

 

I am pretty sure you need a cat to pass smog. I could probley set you up with a new one for $120.00 but you'll need to drive to north sac.

 

I'm gonna offer an answer from Corvette Fever.
Yes, it's so related......
Hope this helps ya
"I have a 1987. The temp gauge maxs out constatnly, but the engine is not running hot.
There was a Tech Serv Bulletin that reads...
"Temp Gauge False Indicated Overheating COndition". I cannot find info on the remedy"
Answer-
"The 1987 Vette has a Temp Sending Unit in the passenger side cylinder head between #6 & #8 cylinder (our V6 is in top back of pass head). IF the DARK GREEN WIRE SHORTS TO GROUND you'll see an overheat condition on the guage.
The DARK GREEN WIRE IS IN A HOSTILE ENVIRONMENT where exhaust heat is constant & is routed close to the engine block. This wire can become PINCHED. (I am not typing all responses just ones for a V-6 application).
It is also possible that the Coolant Temprature Sending Unit is shorting to ground, but this does not happen too often.
DISCONNECT the COOLANT TEMP SENDING UNIT DARK GREEN WIRE &
run the engine to see if the temp gauge is LOW at all times.
IF the gauge is LOW at all times, replace the sending unit."
Yes, our Corvette & our F Bodies do possess these items & this could be your problem, also.

 

Thanks for the offer on the cat, but if it turns out that I need one I can one locally for $55 less. I love competive markets!!!

I check that wire out. I replaced the sending unit, but on the 3.1 it is on front of the head. I checked on the back and there is no sending unit there. I'm getting the feeling it might be a problem in the gauge cluster or even the gauge it's self. But I will start at the beging of the line and work my towards the gauge cluster. After that I will to figure out whats causing the fan not to turn on at the correct time. The fan is controlled by a diffrent sensor and I have replaced that one as well.

Can't find my service manule at the moment so does any one the test procedure for the fan operation? I knoiw the CTS is supposed to tell the ECM what the engine temp is and then at 200 degrees the ECM is supposed to turn the fan on. What I need to know is what pin does the CTS comunicate to ECM on? If I knew this I could check the entire wire before replacing the ECM.

 

I happen to have meet the guy that currently owns the Corvette from that movie. He lives around the corner from a client of mine in the city of Lake Forrest- south Orange County.

 

That took awhile to sink in LOL!!
I was flipping thru the latest Corvette Fever issue & it hit me hard.
If ya ever find Laurel who drives a 1976 with a Can Am kit attached and was in several car mags back then, let me know.
She appreciated that I recognized her when she exited her Corvette back in 1983 or so.

What High School was Corvette Fever filmed at?

LHD, interesting platform, then add a custom outrageous Corvette body.
Oh why not, that's the 70's!
Could pick up Classic Corvettes by falling backwards, such easy pickings!