Help with some problems with my 92

[jcruz]

Hi all,

After a few years I'm finally able to spend time troubleshooting some problems with my 92. About 43,000 miles. I've had the car 9 years and only put about 2000 miles on it.

I'm sort of stuck on what the problems are and how to get them fixed, so I'm looking for any information, leads, advice, ideas, and other helpful information to make some progress.

Gathered some pics & vids last weekend when I had a chance to get the car up on a lift.

Issue #1 -- my car stinks

I'm having some sort of exhaust problem(s)...the exhaust stinks, so bad my wife won't ride in the car any more. The smell is bad in the cabin and, as you can imagine, worse when sitting at a light. The kind of smell that stays on you and can give you a headache. Seems like I have an exhaust leak of some kind.

Here's a short vid of smoke from the exhaust:

https://vimeo.com/504324317

I get a LOT of condensation out of the muffler. Black:

http://www.cruzeware.com/1992-043/info/Exhaust1.jpeg

Also, I'm wondering if there might be something wrong with the catalytic converters, so I took a vid with the engine running. Is this useful in any way?

https://vimeo.com/504323929

Issue#2 -- Clunk/click in the rear somewhere

When the car is cold and moving, I hear an intermittent clunk/click that's driving me crazy. When it happens, you can feel it in the steering wheel. When things warm up, like by the time I get out of my driveway, problem goes away. I first thought it was the brakes binding but I think now it might be a bad U joint or bad spline? The half shafts looked okay but the rear seal seems to be leaking badly. We checked the rear fluid level and to my untrained eye, this oil looks like it really needs to be changed:

http://www.cruzeware.com/1992-043/info/Rear1.jpeg

http://www.cruzeware.com/1992-043/info/Rear2.jpeg

Here's a couple pics around the rear seal area. The cover and the surrounding area were very wet.

http://www.cruzeware.com/1992-043/info/RearSeal1.jpeg

http://www.cruzeware.com/1992-043/info/RearSeal2.jpeg

Should I plan on replacing the seal and seeing what else might be wrong when I'm in there?

Issue#3 -- car stumbles under hard acceleration

Not sure where to start with this one. The car stumbles/bucks badly no matter what speed. With the power key on it's not quite as noticeable. Idles fine and runs smoothly under normal driving conditions.

I had the coils replaced a few years ago. That helped a bit, but didn't solve the problem. I've never changed the plugs, had the injectors replaced, or anything else done on the motor.

What can I do to help diagnose & isolate this issue?

Issue #4 -- what's this port?

A question, really. This port looks like it needs some kind of hose attached. There's a matching port on the other side of the plenum. It looks like someone re-routed the hose so it now goes around the front of the plenum? Wondering what should be hooked up to this port and if it might be contributing to issue #3?

http://www.cruzeware.com/1992-043/info/Outlet.jpeg

Thanks in advance for any information you can provide!

John

[-=Jeff=-]

Issue 4.. is was for Coolant to keep the TB warm for cold days.. it is bypassed on your car.. typical mod..

Issue 2.. the front pinion seal seems to be leaking, Might be good to have the differential checked when the seal is replaced, assuming the unit needs to come apart for the replacement of the seal. The clunk could be a u-joint

[jcruz]

Issue 4.. is was for Coolant to keep the TB warm for cold days.. it is bypassed on your car.. typical mod..



That makes perfect sense: the car came out of FL originally, but I bought it from someone in NY who was road racing the car. Car is now back in FL where it belongs ;-)

[EthanCohen75]

Regarding issue 3, maybe check the link below:
http://www.autotap.com/problem4_engine_hesitates.asp

In short, these could be the issues:
Mass Airflow Sensor
Fuel Pump - doesn't give enough fuel to the engine
Throttle position sensor
Dirty/failing fuel injectors - might be dirty and have to be cleaned/exchanged.

[dredgeguy]

How old is the gas in the car? Could old gas account for condensation and smell? Old gas stinks.

[A26B]

The black, sooty condensation from the exhaust at first startup of the day is symptomatic with leaking injector housing gaskets at the cylinder head interface. Coolant seeps into adjacent intake port, accumulates & blows out on first cold start of the day.

[WARP TEN]

Question: Does your car have catalytic converters or have they been removed for headers? It looks like your exhaust is stock from the video but I also had a stock system from headers back on my '95 but removed cats to go with headers. I also regularly had a bad smell on startup but that was the old smell of the '50s and '60s--before cats, when we tuned cars by smell and the look of the smoke out the exhaust. If your car does have cats, is it possible they have become non-functional? If your cats are fine and you think you have an exhaust leak it would have to be ahead of the cats to produce the smell you describe, I would think, which would mean headers. Certainly an exhaust leak should be corrected. Also, my take on the "smoke" and moisture from the mufflers is that it is simply condensation and entirely normal. I also had it. The pipes are lower than the muffler outlets for much of their length and a lot of moisture can accumulate in them. Drive for an hour or so then see if you get much on a cold start afterwards. As to a clunk in the suspension somewhere, I also had such a clunk especially when I backed out of my slightly inclined driveway, afterwards normally I wouldn't notice it. While everything looked fine, Marc changed the sway bar bushings and that solved it--no more clunk. My car had only 30k miles on it but the bushings just got old and hard. You indicated you felt it in the steering wheel so maybe front bushings need a look. --Bob

[secondchance]

Issue #2:

If clunking noise is when you go over left to right uneven road (car swaying left to right), I would suspect worn out rear sway bar bushing. I recommend urethane bushing since OEM rubber bushing will fail quite fast.

If clunking noise is from directional change as in forward, stop, reverse, most likely driver side rear bearing hub being torqued to 160 lb-ft. This was revised to 190 lb-ft by Chevrolet.

[jcruz]

Regarding issue 3, maybe check the link below:
http://www.autotap.com/problem4_engine_hesitates.asp

In short, these could be the issues:
Mass Airflow Sensor
Fuel Pump - doesn't give enough fuel to the engine
Throttle position sensor
Dirty/failing fuel injectors - might be dirty and have to be cleaned/exchanged.

I'll start researching each of these areas....many thanks

[jcruz]

How old is the gas in the car? Could old gas account for condensation and smell? Old gas stinks.

I run the car regularly enough and the gas is not too old. But, good idea...I'll run through a tank.

[jcruz]

Question: Does your car have catalytic converters or have they been removed for headers? It looks like your exhaust is stock from the video but I also had a stock system from headers back on my '95 but removed cats to go with headers. I also regularly had a bad smell on startup but that was the old smell of the '50s and '60s--before cats, when we tuned cars by smell and the look of the smoke out the exhaust. If your car does have cats, is it possible they have become non-functional? If your cats are fine and you think you have an exhaust leak it would have to be ahead of the cats to produce the smell you describe, I would think, which would mean headers. Certainly an exhaust leak should be corrected. Also, my take on the "smoke" and moisture from the mufflers is that it is simply condensation and entirely normal. I also had it. The pipes are lower than the muffler outlets for much of their length and a lot of moisture can accumulate in them. Drive for an hour or so then see if you get much on a cold start afterwards. As to a clunk in the suspension somewhere, I also had such a clunk especially when I backed out of my slightly inclined driveway, afterwards normally I wouldn't notice it. While everything looked fine, Marc changed the sway bar bushings and that solved it--no more clunk. My car had only 30k miles on it but the bushings just got old and hard. You indicated you felt it in the steering wheel so maybe front bushings need a look. --Bob

Still has catalytic converters and the exhaust is stock. I'll have to inspect more in front of them.

I hear you on the smoke and condensation, but fortunately, I have my 91 to compare to and in the same conditions, it produces no noticeable smoke or condensation, whereas the 92 is VERY noticeable.

Clunk/click only happens going back and forth. Just based on their age, I'm planning to replace the bushings when I can.

Thanks for your thoughts!

John

[jcruz]

Issue #2:

If clunking noise is when you go over left to right uneven road (car swaying left to right), I would suspect worn out rear sway bar bushing. I recommend urethane bushing since OEM rubber bushing will fail quite fast.

If clunking noise is from directional change as in forward, stop, reverse, most likely driver side rear bearing hub being torqued to 160 lb-ft. This was revised to 190 lb-ft by Chevrolet.

Only happens back and forth. Yes, will use urethane bushings! I'll check out the torque spec

John

[jcruz]

The black, sooty condensation from the exhaust at first startup of the day is symptomatic with leaking injector housing gaskets at the cylinder head interface. Coolant seeps into adjacent intake port, accumulates & blows out on first cold start of the day.

This sounds like a significant effort and I'm certain would be beyond my knowledge/experience to tackle.

I've been thinking about sending the car to Haibeck for an overhaul and engine refinishing, but I want to gather much more information before I commit to that kind of time and expense.

I've only done limited research on Marc's services so far...I'm assuming the housing and gaskets would be inspected/replaced if necessary?

Thanks for the valuable info,

John

[DRM500RUBYZR-1]

1- pull the plugs
2- look at the plugs
3- one or more will be black
4- replace the plugs
5- ONLY AFTER you replace the Injectors

With as much carbon and soot you are showing, it looks like your injectors are dumping fuel. Likely failed due to alcohol as they are pre 93.

Your ZR-1 requires basic maintenance including plugs and injectors. It is 28 years old.

I would also agree with an earlier poster that you also likely have leaks at the injector housings, but start with the simple stuff, if injector replacement resolves the issue, stop there. If not; then have a round two.
:cheers:
Marty

[wfot]

I have a set of injectors up for sale currently, they are accel 21 lb injectors that already have the secondary nub filed done, so they are ready to install with all O-rings -
the injectors are a number one issue with the 90 - 92s.

https://www.zr1.net/forum/showthread.php?t=32652

Just an FYI
John

[jcruz]

1- pull the plugs
2- look at the plugs
3- one or more will be black
4- replace the plugs
5- ONLY AFTER you replace the Injectors

With as much carbon and soot you are showing, it looks like your injectors are dumping fuel. Likely failed due to alcohol as they are pre 93.

Your ZR-1 requires basic maintenance including plugs and injectors. It is 28 years old.

I would also agree with an earlier poster that you also likely have leaks at the injector housings, but start with the simple stuff, if injector replacement resolves the issue, stop there. If not; then have a round two.
:cheers:
Marty

Will follow this advice. Here's a pic of one of the plugs...we pulled 2-3 and they all looked like this one, or worse.

http://www.cruzeware.com/1992-043/info/Sparkplug.jpeg

[jcruz]

I have a set of injectors up for sale currently, they are accel 21 lb injectors that already have the secondary nub filed done, so they are ready to install with all O-rings -
the injectors are a number one issue with the 90 - 92s.

https://www.zr1.net/forum/showthread.php?t=32652

Just an FYI
John

Let me do more research on injectors and what's involved, then I'll get back to you...thanks for letting me know!

John

[wfot]

:thumbsup:

[XfireZ51]

BTW, the LT-5 does not use a Mass Air Flow sensor. It is a Speed Density motor w a MAP sensor.

[Young1]

Jkruz, I can take care of your under plenum needs. Send me a PM with your contact info and we can talk.