1990 Having issues

[Dark90]

Hello everyone. New member here. My 134,000 mile Coupe is having a few issues.

Problem 1: After turning the car on from a cold start and running for about 5 minutes I get an extremely rough idle. RPMs drop to about 400-500 and I get black smoke out of the exhaust. This lasts for a few minutes and then RPMs jump back up to the factory idle and I get a Lean exhaust code. 5-10 minutes after that the problem dissapears. I've noticed that if I unplug my TPS once the car stops acting weird, there is a seat of the pants difference in acceleration.

Problem 2: I broke the right side fog light a couple weeks ago and replaced it with the correct size bulb. After replacing it, my right front turn signal/parking light would not work. After discovering that the bulb socket grounding pin wasnt grounding properly, I spliced in a new socket(correctly) and now the signal will not flash. It burns at full brightness as if stuck in the middle of a flash and the right side turn signal indicator on the dash is lit dimly.

Problem 3: Was cleaning up under the hood and noticed that I now have the dreaded L98 rear intake manifold leak. A couple days after noticing this, my clutch began to slip. I'm going to get them both replaced but I don't have the $$$ to get them fixed at the same time. My question is which should I replace first? I'm afraid that the oil is leaking down into the bellhousing and oiling my clutch. The car is my daily driver, and is still driveable at regular traffic speeds, however jumping on the accelerator is out of the question. The lowest estimates I could get for a gasket replacement is $550 which seems kind of outrageous, and $350 for the clutch replacement which sounds great. I'd hate to get the new clutch put in, only for it to get oiled and disintegrate again. Any suggestions would be appreciated. Thanks guys.

 

[tmkassin]

Fix the gasket yourself. It's not that difficult. On the turn signal it sounds like you have the ground wire crossed with one of the other wires.

 

[sstearns2]

Hi,

On the intake gaskets I would just put a bead of red RTV down there and forget about it. Let the car cool, dry it and clean it as best you can down there and RTV it. Not worth $550, it is a lot of labor to change. I paid the $550 years ago when I had my 89 and regret not just RTVing it.

The clutch is just expensive. There are a bunch of clutch replacement threads if you search. You did well to get 134K miles out of it.

For #1 I'd start by pulling the throttle body off and cleaning it out really well and pull the idle air controller off the bottom of the TB and clean it and it's bore really well. Q-tips and eat off of it kind of clean.

Have you checked the fuel injectors for resistance? If they are original they need to be replaced, but with that many miles they may have been replaced already.

Scott

 

[KANE]

Problem 3: Was cleaning up under the hood and noticed that I now have the dreaded L98 rear intake manifold leak. A couple days after noticing this, my clutch began to slip. I'm going to get them both replaced but I don't have the $$$ to get them fixed at the same time...

If you lived closer, I'd say go get the parts, some beer, and head on over and we could fix that gasket over a Saturday afternoon. It isn't that hard. The hardest part is draining the coolant and getting the TPI runners off.

 

[G Winter]

That estimate for clutch replacement seems way , way low
even if that is only labor.
I don't think the oil from the intake will get on the clutch.
If you have the original clutch and flywheel do not replace only the clutch, it most likely won't last. The dual mass flywheel is a problem. Check search for clutch and or flywheel threads.

Glenn

 

[vetteoz]

Have you confirmed leak is from intake? The oil pressure sensor can go bad and leak.
(not uncommon)
In any case the oil runs down the outside of the block / bellhousing so unlikely it would get on clutch

 

[Schrade]

Hello everyone. New member here. My 134,000 mile Coupe is having a few issues.

Problem 1: After turning the car on from a cold start and running for about 5 minutes I get an extremely rough idle. RPMs drop to about 400-500 and I get black smoke out of the exhaust. This lasts for a few minutes and then RPMs jump back up to the factory idle and I get a Lean exhaust code. 5-10 minutes after that the problem dissapears. I've noticed that if I unplug my TPS once the car stops acting weird, there is a seat of the pants difference in acceleration.

Problem 2: I broke the right side fog light a couple weeks ago and replaced it with the correct size bulb. After replacing it, my right front turn signal/parking light would not work. After discovering that the bulb socket grounding pin wasnt grounding properly, I spliced in a new socket(correctly) and now the signal will not flash. It burns at full brightness as if stuck in the middle of a flash and the right side turn signal indicator on the dash is lit dimly.

Problem 3: Was cleaning up under the hood and noticed that I now have the dreaded L98 rear intake manifold leak. A couple days after noticing this, my clutch began to slip. I'm going to get them both replaced but I don't have the $$$ to get them fixed at the same time. My question is which should I replace first? I'm afraid that the oil is leaking down into the bellhousing and oiling my clutch. The car is my daily driver, and is still driveable at regular traffic speeds, however jumping on the accelerator is out of the question. The lowest estimates I could get for a gasket replacement is $550 which seems kind of outrageous, and $350 for the clutch replacement which sounds great. I'd hate to get the new clutch put in, only for it to get oiled and disintegrate again. Any suggestions would be appreciated. Thanks guys.

Welcome onto the boards there.

I've seen a few L98's with intake-to-head coolant leaks, but not oil leaks, except at the valve cover gaskets. I gotta' agree if it is oil, it's probably not gettin' to the clutch.

Unplugging the TPS is not a diagnostic clue. Doing so with the ignition on will re-set a few operating parameters, and it will take a few closed loop drive cycles to re-learn, and then show the same problems.

The low and high idle loping is curious; how long is the cycle? A few seconds? Or minutes? Is it regular up and down, once warmed up?