pshat

Hi all, I have a 92 3.1 auto camaro 175k, all stock. I haven't run out of ideas just yet and I'm still trying new things, but wanted to post to keep track of what I'm doing, get new ideas, and this might help others. This is my DAILY DRIVER so a motor swap, head removal, or something that will disable the car for a long period of time is a little beyond what I want to do for now.

First Day of Ownership:
Car was known to overheat, owned by a teenager, leaking oil, low on power, garaged and not ran for the last two years, and ran rough. Bought it cheap. After fixing everything I could, it has been my daily driver for 2+ years now.

Pictures Say a Thousand Words:
https://www.thirdgen.org/g/album/5051730

Main Issue:
At ANY speed and ANY rpm, if the throttle position is below 20% the tach and motor bounces 200rpm, and the car stumbles and kicks almost like too much spark advance or too lean.

If I rotate the distro and put it at 0 BTDC, I have low power but the stumble is 95% gone (I also can assume I'm loading the engine more to maintain the same speed, so this "fix" may be invalid).

While in park/neutral, there is an intermittent miss, but around 6-20% throttle, the car hunts around 50-100rpm (no miss) trying to maintain a steady rpm.

If I put the car in drive and powerbrake, it has smooth rpms up to 16% throttle then it starts missing (log data says I'm at 42 degrees advance and it retards when it misses).

There are no codes being thrown. The log data had low blm when I first got the car. After all the fixes it now has 140-150 BLM at any acceleration (not sure if this is simply enriched acceleration or abnormally high) and around 116 at cruise (not sure if this is highway mode low or abnormally low).

New Parts:
Heater Diverter Valve, Water Pump, Starter, Battery, Fuel Filter, Fuel Injectors, Air Filter, Transmission Filter, Vacuum Canister, Timing Chain, Timing Chain Gears, Timing Chain Guide, O2 Sensor, Manifold Air Temperature Sender, Spark Plugs, Spark Plug Wires, Coil, Distributor, ICM, PCV, Throttle Position Sensor, all Vacuum Hoses under the hood and Check Valves.

Blocked devices:
Smog pump - A new catalytic converter was installed without an air input (before my ownership) so it was pumping directly to the manifold. I assumed that throws off the o2 sensor since originally the smog pump is only suppose to go to the manifold on warmup.

EGR - Found an air leak in the bendable tube from the egr to the intake, so blocked for now until I can repair the tube.

Other Issues:
Overheating - The water pump gasket was leaking and the heater diverter valve was leaking, I can assume the prior owner drove like this for a substantial time (since this is how I bought the car), potentially overheating the engine numerous times. Now fixed and operating normal. (Don't know if anything is warped, haven't removed the heads)

Oil Leak - During the lower intake gasket repair, discovered hardened oil deposits everywhere. Some of the worst crud I've seen. Doubt it had an oil change in 50k+ . Pulled out the valve covers and push rods and cleaned as much as I could. No more oil leaks.
Idle stumble - Always had a miss or stumble at idle from day one.

Tools:
I have the moats serial to usb adapter and TunerProRT for my laptop to log/view data. If you want an export or snapshot of my data, let me know. I have a good number of mechanic tools, but still just a home garage DIYer.

Checklist:
Fuel Pressure - 38psi idle, 45psi off idle. Fuel pressure drops about 2-4psi over 20 minutes across three tests.

Fuel Pressure Regulator - Tested with vacuum pump, fuel pressure changes to vacuum, and does not leak gas when the car is running and vacuum line is unplugged.

Exhaust Test:
Taken to a local shop and exhaust tested for leaks just to be sure. (Smoke from the oil leak made me think it was exhaust)

Compression Test:I don't recall the exact numbers, but all cylinders were around normal and no significant differences from each other.

Leak Down Test:
Multiple cylinders had valves leaking. Tapping the springs with a rubber hammer would fully shut the valves. May be valve sleeves leaking leading to gunk on the valves, and/or weak springs?

PCV:
Old one was caked in oil, didn't rattle, replaced it.

Spark Plug Tester:
All the wires fire normally.

EGR:
Air leak in the connection flex tube, disabled for now with block off plate at both egr and intake.

Intake Air Control:
Removed and cleaned (Black and white deposits)

Manifold Air Temperature:
Rusted and dirty, replaced. TunerPro MAT temp normal.

Timing Chain:
Distro rotor had a lot of play, replaced timing components.

Thermostat:
With a lot of idle time in the city I replaced it with a 180 degree one.

Throttle Position Sensor:
Old dirty one, replaced. Checked with Tunerpro and analog voltmeter for readings. Voltages at idle and WOT correct. Seems steady throughout position changes. Think I need a scope to do it completely right?

Distributor:
Completely rusted, had to be the original, replaced.

Ignition Control Module:
Completely rusted and missing thermal compound, replaced with new distro.

Ignition Coil:
Seemed to be generating spark just fine during spark test, but replaced just in case.

Map Sensor
Put my vacuum pump on it and no leak and voltages all line up to spec.

Charcoal Canister:
Replaced all hoses and air control valve. Control Solenoid works normal under vacuum and energized. Removed canister to make sure it wasn't full of gas, no gas.

Smog pump:
Diverter Solenoid on the back of the pump was not holding vacuum and catalytic converter was non-air type. Disabled smog pump by getting a smaller belt and blocking the pipe to the exhaust manifold.

Transmission:
Dropped pan, normal wear/color. Changed filter and fluid.

Rear-end:
Changed differential fluid, seemed normal and no abnormal wear.

ECM:
The ECM has "AZTY" on the outside, so it should be the latest working ecm. Also has "SERV. NO. 01227730" and "861331-M111087869" on the outside. One concern is opening it up it has "DELCO AZTY 1407" on a sticker. The other post said it should be "1406" is this a problem?

Injectors:
Ohmed them all, three were bad. Replaced them all with Bosch 17lb/hr upgraded injectors. (So I can use them now and also if I upgrade to a 3.4 block in the future)

Fuel Filter:
Looks almost like the original one that came with the car. Replaced it. I could just barely blow through it, it had to be massively restricted. Maybe that restriction backed up to the fuel tank? Car seems to run fine at WOT.

Timing:
92 camaro 3.1 timing should be 10 BTDC and connected to the front passenger side plug... right?

Spark Plugs:
https://www.thirdgen.org/g/picture/5051735

Firing Order:
Should be 1 2 3 4 5 6

Spark Plug Firing Position:
REAR
5 6
3 4
1 2
FRONT

Distributor Firing Order:
_3_4_
2___5
_1_6_

Fuel Trim:
My BLM's have always been low at idle and during highway mode/cruise, around 116. Is this normal? I upgraded the fuel injectors to 17lb/hr recently and will have to update you on the latest BLM numbers.

Ground Straps:
Ground strap on the rear of the passenger head was completely broken off. Rewired it. Ground strap on passenger side head looks ok, ground strap under the water pump looks ok, mini ground from battery to the headlight area looks ok.

To Do List:
Fix EGR pipe and unblock EGR (EGR Light only SOMETIMES comes on during a drive. Maybe car thinks EGR is working when it's actually blocked...? I should probably unplug it for the time being...)

Re-Test ignition system (Still think I'm having an ignition issue.)

Drop tank and replaced fuel pump (Could be a fuel delivery issue at low throttle...?)

My Guesses:
1- Fuel delivery? Where is the fuel going or is there a restriction somewhere? Fuel pump going bad?

2- Internal oil leak? Maybe seepage through the valve seals. There is a light puff of blue smoke on startup. None once running. I don't seem to be losing any oil.

3- Air leak? I have checked and rechecked all the external air lines and even tried plugging them all. No change. I have sprayed two cans of carb cleaner all over the engine while running. Maybe internal?

4- EGR? EGR light not coming on most of the time, does the car think the EGR is actually working and is throwing a fit while cruising?

5- Badly abused engine, loss of oil, loss of coolant, and overheating in the past, it's a lost cause and put a 3.4 block in there already.

Lucid

iTrader: (4)

Does this car still have the original catalytic converter? If it was overheated, there is a good chance that the catalyst melted and is clogging up the exhaust pipe.

I overheated my engine once and cracked the head. White smoke pillowed out the exhaust pipes at startup and it ran really rough. Even after having an engine mechanic replace the head, the car had no power.

I had an exhaust shop raise the car and bang on the cat, and you could hear the crap inside bouncing around. I had the cat replaced with a high flow universal and ended up having to replace the muffler because it was full of junk.

Are you having mysterious coolant loss or overheating still?
Have you read the original plugs that were in the car? Were they colored white or anything like that?
Is the oil like chocolate milk?

Something tells me that engine was abused.

pshat

Thanks Lucid for the reply.

The cat and everything behind it was replaced before my ownership with a non-air type converter. Overheating and high BLM's during my first ownership could easily point to a ruined converter. Also should mention, I haven't seen it glow red after a hard run and I can run WOT without issue, so I haven't pursued a restriction there.

Wow, that's too bad. That is a big concern that there is an internal leak and/or warpage. I have not noticed oil mixing with coolant or coolant mixing with the oil in the few drains/refills that I've done. The oil levels and coolant levels seem to be unchanged since I've owned it (after fixing the initial leaks). There is a very faint puff of blue smoke on startup after sitting for a few days, but no white or blue smoke thereafter. The car seems to have most of the 140hp it was originally built with and WOT pulls good for it's age/abuse.

Since the cat and back has been replaced, I haven't tried even looking there for issues, other than having a shop leak test the exhaust system. I may have to look look more closely and consider doing a flow test to make sure the cat is not clogged. Great idea!

No coolant loss or change of color, no oil loss or change in viscosity. No more overheating and no more oil leaks (definitely had both when I bought it) When having the valve covers and lower intake off there was a huge oil deposit buildup problem. I can only imagine what problems that may have and will cause. Here is a picture of the plugs not too long ago. I need to pull them again and check their color now. https://www.thirdgen.org/g/picture/5051735

ABSOLUTELY. Owned by a teenager who knew nothing about cars, let it overheat and leak oil for who knows how long, then put it in his garage for the last couple of years thinking he'd eventually work on it, never did, and now I have it. It is very easy for me to say the engine is shot and needs a new one, but I'd like to argue that it is a daily driver and a reliable car (2+ years now) and the only issue is light throttle.

I am uber grateful for your help and anyone else reading this. Also, I wanted to add I am putting up pictures. https://www.thirdgen.org/g/album/5051730

pshat

Update:

After a little more critical thinking, this can be broken down into four possible areas.

Air:
1: Need to fix the EGR flex pipe, remove the block off plates, and plug the EGR back in to the harness.
2: Have not replaced the IAC yet, may consider this since I've never visually seen it working.
3: The upgraded 3.1 to 5.0 air inlet originally near the coolant reservoir now to the dual intake under the front bumper adding too much air now...? Problem existed before this change though.

Fuel:
1: Old fuel pump and rusted fuel lines may need replaced. Possible fuel volume, restriction or other problem in the tank. Fuel filter was almost completely blocked when changed. WOT and every acceleration except cruise works fine, could it really be fuel related?
2: Used both stock and 17lb/hr injectors and noid light, all seems ok but could be intermittent that I couldn't see?

Spark:
1: Faulty new ignition component? Everything was replaced.
2: Spark plug wires were arcing to the block. After fixing the head ground and removing the outer aluminum heat shield on the plug wires, they no longer arc. Are the wires still bad if they do not jump again? Would it arc only at cruise? I don't think so right?
3: Used timing light on all wires to maybe find intermittent spark. Did not notice anything wrong.
4: Received multiple lights that go between plugs and wires, will test for any intermittent spark on all cylinders at once.
5: I hear the Ignition Control Modules go bad all the time, maybe mine is bad? But only at light throttle though?
6: Could the ECM be bad and throwing off the timing/spark?

Mechanical Failure:
1: Compression test was good, could it be valves only sometimes not sealing even though compression looks good?
2: Leak down showed some valves were not fully closing and sticking. Seemed minor but could easily affect a lot. I have an endoscope on order (7mm) so will take a closer look down inside the cylinders and should have more info on the internals shortly.
3: Other major anomaly, highly likely and the only other fall-back if nothing else is found.

Pupkin

Hi,

thanks for this interesting thread.

Where are all these ground straps which you mentioned? Do you have pictures of them?

Thanks.