Mechanics

CHEVY THIS CAR HAS SEEN BETTER DAYS.

1992 Chevrolet Corsica

Engine Performance problem
1992 Chevy Corsica 6 cyl Front Wheel Drive Automatic 178k miles

I have a 1992 Chevy Corsica. It has a cracked block, but the block was welded. I bought it from a friend in June of 09. I didn't spend much initially, but since I bought it I've spent about $300 semi reviving it. Which is much more than I spent on the car. Now its idling is fairly sporadic when I first start it up, but it doesn't die. The engine runs rough and feels as though there is a loss of power, and the idle jumps up and down. However, if I shut it off before the first 1/2 a mile or so, it has trouble starting again. It will turn over, fire, but lose its idle. Its idle isn't really bad. I guess its bad enough for someone who pays attention to notice. But it affects the braking sometimes. It feels like the car is still trying to accelerate when the idle is up, but goes away once the idle goes back down. It also sputters before going from a dead stop (i.E. Stopping for a stop sign) when I use the accelerator. After the car has been driven for about a 1/2 of a mile, it accelerates like normal, and doesn't stall before accelerating. But the idle is still irregular. The car also runs at a strange temp. The gage is accurate, but the needle tends to hover around the 3/4 line. I replaced the thermostat a month or so ago because the one in the car was not opening all the way, causing the car to overheat. I replaced it with the spec t-stat for my car (195degree setting) It is in there the right(i didn't know it was common to put them in backwards). For a while after replacing, the gage was really sporadic, fluctuating between 1/4 and 3/4 marks. Now it has plateaued around 3/4. (Is that normal?) But it has not overheated on me since. With the recent rough idling/accelerating, I tried a fuel injector cleaner. Didn't help. I replaced the air filter and fuel filter. It helped a bit, but its still not running right. My next step is plugs and wires, but i'm wondering. Would the fact that the engine had overheated, blow the welded crack on the block? It would explain the loss of compression and irregular running habits. I was thinking maybe the camshaft sensor, but I haven't seen the 'service engine soon' light once in the 4 months I've had the car. And I'm pretty sure if it was a sensor, the light would register a problem. I know enough about cars to know that there's something wrong, I just can't figure out what. I'm sure there are many problems. But the most desperate right now is my engine stalling out and idling sporadically. I'm out of ideas, please help?
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Slide87
September 23, 2009.




Hi there Slide87 and TY for the donation

But the most desperate right now is my engine stalling out and idling sporadically.

Lets take it step by step

Lets try cleaning out the idle air control, the EGR and PCV valves, also check and test the throttle position sensor closed and WOT voltages and the manifold absolute pressure sensor and comeback with the testing results so that we can continue to find and fix it for good

Tiny
Rasmataz
Sep 23, 2009.
Ok, the valves have been cleaned. They all looked to be in fair condition. I don't know how to test the WOT voltage, and I do not have the pressure sensor for the manifold. Is there another alternative way to test? Or can you explain the procedure for testing the WOT voltage? What type of pressure sensor do I use for the manifold? The only pressure sensors I can find for my car are the a/c pressure sensor, the coolant temp sensor, and the fuel and oil pressure sensor.

Tiny
Slide87
Sep 23, 2009.
No check engine light -Disregard the TPS/MAP lets put new plugs and wires and run an injection cleaner-if it continues-check for vacuum leaks and low fuel pressure.

Tiny
Rasmataz
Sep 24, 2009.
I replaced the plugs and wires today, and the car is running much better. There is no longer a hesitation in the acceleration. However the idle is still irregular. Not as bad, but it still fights over up and down, if that makes sense. It is close to a normal idle, but jumps up and down slightly, causing the engine to rock back and forth a bit. What else would cause an idle to do that if the idle air control sensor is functioning properly? And is it ok that my temp is higher than normal? Thank you for your time and patience with me. : )

Tiny
Slide87
Sep 24, 2009.
Try cleaning out the IACV thoroughly again and its passages and see what happens
AD

Tiny
Rasmataz
Sep 24, 2009.
I pulled it again, cleaned it and the idle has returned to normal. Thank you : ) Now as for the temp, is it normal for it to hang out around the 3/4 line? Also, I found a fresh pool of antifreeze below the thermostat housing. I thought that maybe the seal I had created when I replaced the thermostat last time had leaked, so I pulled off the housing for the t-stat and resealed it with a special order gasket (as it stands, my make and model car requires no gasket) and more Permatex gasket sealant. I let the car sit all day today to give the sealant full time to cure, but it didn't look like the seal I made the first time leaked at all. I'm thinking maybe the housing is warped from the heat. Its an aluminum housing, would heat cause it to warp like that? It didn't look warped, but I know it doesn't take much of an imperfection to cause a small leak under that much pressure. I'm hoping that the gasket will help to compensate if there was an imperfection, but is there a place where the antifreeze can leak from the bottom of the housing, where I cannot see so well?

Tiny
Slide87
Sep 25, 2009.
Retest the thermostat and inspect closely if the housing is warped and try better sealant than permatex

Tiny
Rasmataz
Sep 26, 2009.
What sealant is better than permatex? The Permatex is the best sealant that most of the auto shops around me carry. Can you suggest a better brand?

Tiny
Slide87
Sep 26, 2009.
Permatex been around for ages-I've used it thousand of times since it 1st came into market. For me I just use JB weld for somethjing like that. Just use the permatex it'll be okay regarding you clean the housing mating surfaces thoroughly and wait for it to cure - also test the coolant temperature sensor-

Tiny
Rasmataz
Sep 26, 2009.
I had already pulled the housing and resealed it. It seems to be holding. I'm still finding fresh antifreeze under the housing, but it doesn't seem to affect the level of antifreeze at all. I can't find the coolant temp sensor on my car though. Its supposed to be mounted on the driver side intake manifold, but im not seeing it. Could I be missing it? How do I test it once I have found it?

Tiny
Slide87
Sep 29, 2009.

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