DrummerDad

Wednesday I went to the bank, and it tried to die in the line at the teller. Then it only got worse. At lights it sounds like a prostock car idling. Its down on power, I think. Kinda hard to tell with an L03, but somethings wrong. When I tried to idle into the garage the brakes were way to hard. I almost hit the heatpump. This makes me think its a vacuum problem, and the idle is so rough, I thought it would be a big one. But when I get on the throttle, it appears to clear up, almost. When I hold the gas pedal steady, or let of and get back on, you can feel it stumble( and its been smelling funny lately). Ive chased several vacuum problems before, and always found them (except the stupid one behind the dash causing me to only have a defroster when the heats on), but I found nothing. I pulled the valve covers, to see if there was something wrong, and nothing out of the ordinary. Both injectors appear to be spraying a nice pattern. There is a weird sound in the exhaust, but I figured that was just because of the rough idle. I dont have a timing light, or fuel pressure gauge, yet, but I had the timing set by a shop a year ago, and its been fine. I replaced the fuel pump about 2 years ago. This car has been real good, so far, and even averaged 26 mpg on a 1000 mile round trip this summer. Cold air, cranks everytime, almost everything works. This is unusual. Im planning an engine swap next spring, but it has to work, everyday. Only mods to the engine, are headers, crane cams fireball ignition, and smog lines/pump delete. Head gaskets are about 2 years old, as are all the upper end gaskets, intake, TB, new regulator, etc.. The plugs and wires are even less than a year old.

Sorry its so long. I tried to cover everything, and I searched, and found nothing. Anybody have a vacuum schematic?

Cflick

Have you looked at the plugs lately ?

DrummerDad

Not in about 3-4 months. And I thought of that, because its starting to blow just a little blue smoke. But the more I thought about it, it acts like a vacuum leak. Maybe Ill buy some plugs. Any other ideas? Cause changing 6 of those plugs isnt bad, but Id just about rather take a beating than to have to change the #7, and #2 (I think). With those 1-5/8 headers, it blows.

studdmstr

Is your SES light coming on? If so what are the codes?
when was the last time you replaced your oxygen sensor?

DrummerDad

No codes, no SES light. Sorry forgot to add that. The only light I ever get, is about every 5-6 months, I get an SES for the EGR (forgot the number). Thats because of the exhaust I put on. As soon as I shut it off, it goes away for another 5-6 months. And Ive never changed the O2. I do know I have a few bad sensors. Like the one on the passenger side, under the header, in the side of the block? I think its a knock sensor. Its toast. I killed it installing the headers 2 years ago, and it hasnt hurt anything, to my knowledge. The connector was bad when I got it, I just finished it off.
Its not a perfect car, but I try to keep everything in good running order. It also has a new radiator, hoses, water pump, and heater bypass valve, but I figured those had nothing to do with it either.

studdmstr

In you're first post you said it was smelling funny. Is it smelling like it's running rich when you're standing behind the car or is the smell coming from the engine compartment. Both times I had a weird fuel smell one of my injectors went out and the other time my oxygen sensor went out.

Cflick

I'm thinking fouled plug. A gas fouled plug can do exactly what you're describing.
There are only three ways I know, to know for sure. One is to pull 'em and look at 'em.
That's best. Next is a timing light, which you don't have. Last, is to pull wires one by one while it's running. If you pull a wire and it gets worse, that plug is firing. If you pull a wire and nothing happens, that one is missing !
If you pull a wire only a little ways, say 1/4 inch, and it gets better, that plug is missing.
If you pull a wire and the thing arcs where it isn't supposed to, you can damage ignition parts. ( high ouput coils can arc themselves to death internally very quickly )

If it's ideling poorly, I'd expect the vacuum brakes to not work after about one stop.

DrummerDad

I noticed the funny smell when the header gaskets went away. I replaced them with the dead soft gaskets, and thought it would go away, but it hasnt. I notice it in the garage, and sitting in the driver seat. My wife also said something about it. And Wednesday, when this all started, I could smell it while driving. The window was cracked, and I have a power bulge hood (formula). I am used to the slight burnt oil smell, and thats not it. It has 130K miles. And a seeping front and rear main seal. Not bad, just a few drops here and there. Less than 1/2 quart per oil change.

DrummerDad

The problem with pulling them is the headers. Im not reaching in behind those things. At first I thought fouled plug, but a guy at work thought vacuum. We talked and I thought maybe he was right. Then I thought dead cylinder, thats why I pulled the valve covers. I guess, a fouled plug would cause poor idle, and effect vacuum also. And I havent found any bad vacuum connections, or lines. I guess Ill buy some plugs. Probably needs them anyway.

DrummerDad

Well it wasnt the plugs. I changed them, and its still stumbling. And it seems to be worse. Now it cuts out bad under WOT. Still no SES, or codes. Does anybody have a vacuum line schematic? Heres how bad the plugs were. And they are only about 8 months old.


http://i31.photobucket.com/albums/c3...d/DSC00023.jpg

http://i31.photobucket.com/albums/c3...d/DSC00024.jpg

Cflick

Those photo's are absurdly rich, or bad misfire. The two on the far left are certainly gas fouled.

Thought. Coil.
I know, you don't really want to do this. Neither did I ! ( but I'm glad I did )
Pull whatever plugs are easy. ( we're looking for better/worse, not "fixed" )
Close the gap down to about .010 or .015 or so.
Go drive it. Might not have to. If the idle gets better instantly, you'll know !
WOT puts the highest demands on the ignition system. That's where it's likely to fail first.
Closing down the plug gaps will reduce the demands on the ignition by an order of magnitude. No, I wouldn't leave it that way, but if it gets better, I'd buy a coil !
Closing the gaps will reduce both the breakover voltage the coil has to deliver, and the gas in the gap available to light, so it may still miss a bit, but if it gets better than it is........

My mill was running fine. Shut it off one day, and it wouldn't start. Closed the gaps to .010 and it fired right up. Went straight to the parts store, did not collect $200, and the difference in "fine" was nothing short of amazing when the plugs were gapped to spec.
Different than your problem, but you might be on the edge.

DrummerDad

But its still got the rough idle. And playing with the distributer doesnt do anything. Under full throttle it acts like it did back when the fuel pump went bad. But then it would idle fine, and run great till about 2500rpms. Then it would cut out. The fuel pump is only a couple years old, maybe 3 max. And I never run it low. I go 250 miles, and refill (but thats because the sender is bad). Think it could be a fuel pump, again? And do coils go soft? I always thought that certain components just went bad. Thats why I had such a hard time when the fuel pump went. It didnt make sense that it just one day decided it wouldnt pump enough gas. Still worked, just not enough.

Cflick

That's not the same.

I don't, but I also don't really know. I'd expect a decent idle as you say.

Not normally, but the newer stuff with external laminated cores, do. Takes many, many years. Core rusts, laminates separate, output goes down.

DrummerDad

Im going to check the fuel pressure regulator tomorrow. See if anything is wrong with it. And before I remove those plugs again, Ill buy a coil. Its $19 at advance. If that doesnt fix it, I guess Im going to buy a fuel pressure gauge, and see what the pressure is, maybe a cap and rotor. I might also unhook the ignition box. If that doesnt reveal anything, I guess Ill start testing sensors. TPS, and IAC. I hate to start throwing new parts at it, especially since I plan on replacing it in a few months. Any other ideas are welcome, and Ill continue to update.

I just checked the computer, and got a 12. If memory serves me, thats nothing.

Cflick

I totally agree with *not* just throwing parts at it, but....
The plug photo's show gas fouling, and absurdly rich. ( some wet, one covered with soot )
There really isn't much that can make the plugs THAT bad outside of ignition failure.
Cap and rotor never hurts, same with wires.
The more I think about it, the more I think you got a failing coil. ( or ignition module, or both, except that a module usually fails catastrophicly )


12 says you're doing it right, but that's it. It's an indication that the engine is not running.

resop.27

are you running a cat? because I had that problem it was huge. carwould stumble at anything abot 1500 rpm i did everything every sensor, timing chain fuel pump, everything ended up being the cat being junk. what i did was drill some holes in front of it but yet you dont want to have to cut a cat out for no reason. that was just my problem not saying its yours.

DrummerDad

Yes. A 3" highflow, from catco, I think. It still has its normal throaty exhaust note, it just sounds like its hitting on 5 or 6 cylinders. Seems like a clogged cat would change the exhaust note.


I just tried changing my ign module. I had a known good one, and it didnt work. Also, I tried unplugging my ignition box. It wouldnt even start. I checked the fuel pressure regulator, and it looked fine. Im starting to think youre right. Ill buy a coil tomorrow, and try it. For $19, if it doesnt work, Ill keep it as a spare. The cap and rotor looked bad, but Ive seen alot worse.

DrummerDad

Well the coil didnt fix it, either. Crap, Im starting to get pissed. And I unhooked the ignition box, and its still doing it, with the new coil, so thats not it either. I guess its cap and rotor time, but Im sure that wont do it either. Im going to dig, and see if my old plug wires are in the basement. Might try switching them out too. Could an O2 sensor be doing this? TPS, and IAC wouldnt make sense. Other than that, it appears to be either the pump, or the injectors. And that really doesnt make sense either. Am I missing something?

Edit: a search showed I missed the ESC. Electronic spark controller. If my knock sensors are bad, or even broke, would it think its knocking more or less? Could them being bad cause the ESC to fail prematurely? Its a $70 sensor, so Im in no hurry to run out and buy one. But, a $20 coil, a $20 O2 sensor, and a cap and rotor, plugs.... The bill is growing.

Cflick

Yeah, an O2 could, though I've never actually seen it. I'd expect it to come on gradually, declining mileage and such, but never having experienced it.....
A cloged CAT it would idle fine, run smooth, but no power, no high RPM at all.
Bad ignition ( which you've now pretty much eliminated ) would do it, along with a variety of missing, possibly a poor idle also.
Lesseee..... If the O2 is bad, and you just disconnected it, it would stay in open loop, throw an O2 fault code, but run OK, possibly a bit rich but not like the plugs are showing.
If the O2 were sluggish ( which I hear is the first sign ) and giving a false lean indication, you could get all that fuel, flood, miss, and read even leaner when it's not.

DrummerDad

Im leaning towards ignition, still. Maybe the esc, or the pickup. That makes more sense to me. If the spark control was bad, would I get a code? Even with the knock sensors being toast? Could it be in limp home mode, without an SES light?

1991CamaroRslow

iTrader: (3)

Have you checked the brake booster? Pull the vacuum off it and plug it see if that helps.

DrummerDad

Just tried it. Didnt help.

I unplugged the ESC, and it didnt change anything, either. I am getting one from Advance, and the manager said hed refund the $60 if it didnt work. So Ill try that tomorrow. If that doesnt work, Ill also try the pick up. And Ill dig and see if I have the wires to swap. Ill also try unplugging the IAC sensor while its running, and maybe the TPS, and see what happens. IDK

1991CamaroRslow

iTrader: (3)

When my 4.3 liter S10's TPS went out it would start up sometimes and idle horribly like it was massively cammed; I would rev it a few times and it would come out of that. It finally started giving me stalling problems when i would go to take off from a light and it would also feel like it was giving itself a little throttle when I was sitting still at times. The TPS is pretty easy to test I would check that as well.

RBob

iTrader: (1)

A scan tool would help a lot, it would show you what the ECM is seeing from the sensors.

As for the fouled plugs and chugging engine, the CTS and/or CTS connector will do this. If the ECM thinks the engine is colder then it really is, it will stay in open loop and add fuel.

RBob.

Cflick

Could it be in limp mode without a light ? Not really, unless the light is burned out.
If the light blinks once, then stays on, then goes out when the engine is started, it's not in true limp mode, and the light works.
There are actually two modes. One is limp, where the dist controls spark exclusively. It still sparks OK, but with zero or minimal advance. If the dist module fails, you get NO spark as a rule.
If the pickup fails, you generally get NO spark, but I suppose severe miss is possible. Most likely you would get some kind of failure code from unexpected behaviour. Also, the ECM uses the dist pickup to know that the engine is turning at all. That's the code 12 you get when doing the blink test.
In true limp mode, the SES light flashes from an alternate circuit. True limp is a dead CPU in the ECM. Spark is from the dist module only.
Also in limp mode, fuel is controlled by the TPS almost exclusively.
In a soft-fail mode, if any sensor fails, the ECM guesses where that sensor would be based on the others, and acts accordingly. You definitely get a light. If the TPS failed, the ECM guesses based mostly on MAP ( or MAF ) and RPM, and lights a light. Except the dist pickup, and dist module, because the ECM doesn't know the engine is turning at all, so you get NO spark, and NO fuel. That pickup is a single point of failure for everything.
I'm a bit surprised you don't get a light with a bad knock sensor !?
What the ECM should do, is light the light when the sensor fails the test ( which is the ECM forces a knock situation, and sees that the sensor does respond ) and retard timing far enough to guarantee it can't knock, then light the SES light.
Oh, and IAC is a control, not a sensor. I wouldn't unplug that. If you meant the IAT in the air cleaner, you can unplug that and it should still run OK, but a bit rich. Unplugged it thinks the intake air is -40F or so. Should set a fault when the O2 starts working and it knows something is wrong based on O2 feedback. Then it guesses based on coolant temp.
That you're not getting a light, or fault codes is really puzzeling.
TPS is easy to check with an ohm meter. MAP is easy with a voltmeter. MAF I don't know.
Bad O2, it should run OK for the first minute or three when cold, since it doesn't normally use the O2 the first minute or three anyway, until the sensor warms up and starts working.
Since the plugs are new, pull an easy one and see if it still looks pig rich, though I suspect it will.
If it was me, and me being as cheap as I am, I'd disconnect the O2 and look for two things.
1. That it correctly sets an O2 code within about 5 minutes or so.
2. How it runs in a forced open loop situation. Should be not *real* bad.
Then, I'd disconnect the TPS sensor. I know how that works. It should respond to opening the throttle, but sluggish, and set a TPS code. Still run not *real* bad, but poor throttle response, and the stuff 1991CamaroRslow said.
Then the MAP sensor. ( reconnect TPS ) More responsive, and set a MAP code, but not so good as when connected if working.
You say the pattern from the injectors looks good, but does one leak ? If you just turn the key on, but not crank, fuel pressure comes up. Does one of them drip ?
Puzzeling, challenging, frustrating......

Toehead

You can test the knock module without buying a new one....


The knock esc provides a "high" signal with NO knock is occuring. By unplugging it, you just made the ecm see a large knock count.


Test for about 10 volts on the signal pin (the one that says "to megasquirt"):


I second the vote for the coolant temp sensor. A bad sensor would make the car run in opn loop and very very rich.

DrummerDad

ESC didnt fix it either. Good thing he'll give me my money back.
I unplugged the O2, and ran it to operating temps. Got an SES. Turned it off, and got a 12, then a 13. As soon as it cools enough for me to reach under it, Ill plug the O2 back in, and try the TPS. And I pulled a plug and it look real ashey, and black. The IAT sensor has been moved from the aircleaner to the A/C dryer/accumulator area. Has been for months.

Ill also run down, and try unplugging the CTS to see if it changes.

EDIT: plugged the o2 back in, and now it wont start.

Cflick

How did it run during that period ?

The O2 isn't used until two or three minutes after start, so that's not what's preventing it from starting.
That it won't start......
The ashy black plug says rich. REAL rich.

DrummerDad

Same. It "calmed down" as it warmed up, but then it wanted to die.

I just bought a cap and rotor. Even though the old ones are less then 9 months, and 5K miles old. And Ill switch the wires out too, with an old set, that was working when I last gave it a tune.

And I assume a code 13 is the O2?

Cflick

13 is an O2 failure, yes.
Kinda wish you had a timing light, but as Rbob sugests, some way to know what the ECM is seeing while it's seeing it would be best.
You can check temp sensors with a pan of water on the stove and an ohm meter, but a scan tool would be much better. Wonder if you can borrow one from the parts store ? Harbor Freight has 'em cheap(ish), too, if there's one of them near you.

Rock90rs

iTrader: (3)

The symptoms you describe are exactly what happened when the coolant temp sensor went on my 90 L03. I broke the damn connector off by accident. I never got a code for the coolant sensor.

His rich condition could be causing the 02 code though couldnt it?

Toehead

Only after the car warms up and goes into closed loop. If it is running rich right from startup, it rules out O2 as the cause.

DrummerDad

Just changed the cap, rotor, and wires. Nothing really changed. It got a little better, but not much. Also, I got it running, and unplugged the CTS (I unplugged the one at the front of the manifold, not sure if there are more) and got an SES. Plugged it back in, it went away. I unplugged the TPS, and the same thing happened. RPMs went up a little, and the SES came on, and went away when I plugged it back in. The only other thing I can think of is the pick up, or reluctor. Theres rust under the cap, and maybe thats causing it. And I also heard a slight gurgling from the TB earlier. It sounded like the press. reg. But I checked it earlier this week. A faulty press. reg. could cause a rich condition, couldnt it? And bad injectors ( I checked for leakage, and didnt see any) couldnt, could they?

As for timing, Im going to borrow one from a friend hopefully tomorrow. Ive been moving it manually to try to make it better. I KNOW. Thats not the way to do it. And I planned on timing it, once I got this problem fixed. The whole basement smells like fuel now. And its smoking (white) pretty bad.
----------

I never got a code, until I unplugged the O2. And it went away after I plugged it back in.

Rock90rs

iTrader: (3)

My bad, missed that part. Have you checked into the temp sensor yet?

DrummerDad

Yep. I unplugged it, and got an SES. Plugged it back in, and it went away.

Also, Im still getting the O2 failure. Im thinking thats because I havent ran it long enough to erase it yet. Am I right?

RBob

iTrader: (1)

You will have to excuse me for being so direct: I fail to see that unplugging sensors is a diagnostic of your vehicles problem.

You are still guessing. Which will cost you more money. With a small chance that the problem will be fixed.

Do you realize that the CTS connection is just as important as the sensor? And, that either or both can be bad and not throw a code?

Get a scan tool and see what the ECM is seeing. That will narrow down where the problem is. Simple as that. I previously mentioned the CTS. It may not be be the CTS, it may be the ECM is bad and not reading the CTS properly. It may also be that the connector resistance is high. In that case the ECM will see a low coolant temperature. But until you look at the values the ECM is using, it is a guessing game.

Does the ECM go into closed loop? What are the BLMs when and if it does? Is the FPR leaking fuel? Which will put fuel directly into the engine. Do you have a DVM? That in itself can be used for sensor checks.

RBob.

travishenry

Look on the back of the TB youll find a vacume line inbetween the fuel rails follow that line to the sensor. I think that the sensor is mounted to the passenger side. its black rectangular shaped. Im not sure what its called but i had the same prob with my 88 camaro. It idled like a big motor replaced that sensor and wint back to normal.

Rock90rs

iTrader: (3)

I think youre talking about the map sensor

travishenry

Ya exactly the map sensor. I had one go bad on my car and made it idle like a 350 or somthin with a big cam. I replaced the sensor and boom prom fixed.

DrummerDad

Yes, I understand, maybe not as clearly as some, how electronics work. I didnt want to buy a scanner, because Im planning an engine swap in a few months, and didnt know if it would work on both. I thought the purpose of unplugged certain sensors was to make sure the ECM is catching it (which it has). Also to see if there is a difference in the engine. I dont have $200 for a scanner, or a laptop to connect to the ALDL for datalogging. The only scanner for GM that the local parts store had, was just the little shorting clip, and a $200 scanner. Also, I thought the ecm would record failures. Maybe not specific components, but still as bad as its running, it should be seeing something, and flagging it. And a scanner will give me the values that the computer is reading. Where do I go to find out if those values are correct?
And I stated earlier that I have specifically replaced several components with known good components. I regularly tune the engine, and try to fix it the right way, and buy sensors, just to keep on hand. I havent bought as much, since I decided to change engines, though. I had a coil, MAP sensor, wires, Ign module, and a bunch of vacuum hose. And Im sure theres more that I have forgot. So Im not just unplugging stuff and waiting for a miracle. Guessing maybe, but Ive tried everything that has been mentioned, and even a few things that havent. So, now what?

Toehead

You could try shorting the two pins of the CTS pigtail together with the car running. That should make the ecm see the maximum temperature and would show you that the input was at least working if the car ran better (do it once it really is full hot)

travishenry

maybe try to rebuild the TBI i think the kit is like 30 or 40 bucks. the fuel pressure regulator on the TB might have a blown gasket and the fuel pump is pumpin high press so its causing the motor to run rich so it idles like a big motor. I think the gasket that could be blown is red or like orange. Its kinda hidden. The press regulator is like golden color or some look like jsut plain mettal. Give that a try. Like some one els said some of these motors are like 20 YRS old. So it could be nething.

DrummerDad

Okay. What if I built an ALDL cable, and hooked up a computer. I have a crusty old laptop (its a 166 processor) and tried datalogging with it? I dont know if the laptop is even fast enough, and I dont know how to get a datalogging program loaded onto it, because my computer doesnt have a 3.5 drive, and the laptop doesnt have a cd. Also Im using XP here, and the laptop is ME.

What scanner are you guys using? Will it work with TPI?


What about this one?
http://www.amazon.com/Actron-CP9145-.../dp/B00020BM2S

$130 for it, and an ALDL adapter for OBD1.

racer J

Yes, it SHOULD do that. However, it's not always the case. I have mine disconnected and it has never set a light for it. I had to disconnect it because it's picking up valvetrain noise as a knock and destroying my timing as a result.

travishenry

Im not familar with the computer stuff. Do you know of the TB ever being reebuilt on your car.

DrummerDad

Yes. I rebuilt it right after my fuel pump was replaced, so roughly 3 years ago. I also replaced the fuel pressure regulator, and the filter at that time.

Im thinking about buying a cheap computer from ebay,and doing some data logging. I can build an ALDL cable at work. And Ive already downloaded winaldl. I just have no way to transfer it to my old laptop. If I can datalog it for a trip down the road, it should be as good as using a scanner, right?

RBob

iTrader: (1)

WinALDL will work for your setup. I was going to suggest it if you had a laptop. For a cable, and since your plans are for a TPI setup down the road, make one based on the max232 chip. It is much more reliable then a transistor type. For quick and dirty, the single transistor type is all that is required for your current setup. Problem is that they aren't that good and sometimes don't work correctly.

Don't need the 10K resistor in the ALDL plug either. Leave that out.

With WinALDL you can do some testing while stting in the drive. After the vehicle has sat over night, key-on, engine-off, the CTS should read the ambient temperature. The MAP should read barometric presure (with regards to elevation). Then start the engine and warm it up, the CTS should follow the engine temperature. If the fan switch is stock and working it should kick on about 228 F. Can see what the CTS is at.

Toehead mentioned shorting the pins together on the CTS. That too should throw a SES & code (same as open, different code). Can use a 200 - 220 ohm resistor across the CTS connector. That is about 200 F.

RBob.

gary sanders

sounds like a fuel problem,weak fuel pump or fuel regulater,and change fuel filter..common problem on throttle body,next thing will be the EGR valve,carbon deposits ,clean or change it,all these cause stumble at WOT,AND STALLING.
CHECK YOUR FUEL PRESSURE!!!!

Cflick

If you have the wherewithall to build an ALDL cable, DO IT !! The fastest ALDL I know about, is about the same speed as a fast dial-up internet connection, and you don't have that, so the laptop you have is *more* than adequate. This will remove ALL guesswork, plus you'll gather some very likely needed education for the swap. You can't buy that !
If you can build an ALDL cable, then you can build a null-modem and transfer the program through windows "direct cable" thing, or find a friend with a floppy to get it on a floppy for you. ( find a friend is probably easier )
If your laptop is advanced enough to run ME, it's advanced enough to run practically every ALDL analysis and tuning program out there.

Actually, an ALDL cable, and a laptop ! Beats the pants off a scan tool.
As far as correct values, there are people here on ThirdGen that know more about this than you'll ever want to know. No worry.

Toehead

The single transistor cable will work very well for the TBI, but will not work on the later TPI engines. However, it will work on a 1985 TPI.