96 Corsica -- power loss

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I was hoping someone here could give me some direction on fixing my car.

First the stats: 96 chevy corsica 3.1 V6 auto trans

Right now it feals like im drive with half an engine, it takes forever to get up to speed and the accelerator seems to do nothing but make the car mad.

There is a knock coming from the engine block area when it is in idle

Also it will sometimes rev high while in idle

The problem seems to get b a little better as the car warms up

The problem seems to go away when the weather is warmer, Im in UT and this has been a warm winter, anytime its >40 degrees F outside the car feals like new.

Any suggestions on helping me fix this would be greatly appreciatted.

posted by  morningwood

What colour is the exhaust? Clear(normal), white or black? Does it smell sweet?

Have you been loosing any coolant? (resevoir low? rad low?)

How loud is this knock? If you torque up the motor does it knock a lot louder?

If it's just a silent knock, and when you torque it up the knock just gets faster but not very much louder, that's piston noise, piston's out of round. (Pistons are not perfectly round, they can't be or else it'd rip apart the wall, you know they shape of a cam? The egg shape? that the shape of a piston, of course not that much of a shape, it's hard to tell with just your eyes that it's not round, but no piston is round) When the motor warms up the piston becomes rounder (Physics 101 - Warm metals expand) and sound dedens.

Oh, you a corsica with the 3.1. Problem motors those 2.8's and 3.1's were. Chances are power loss is due to a blown head gasket (they were extremely bad for it, I've gone through 2 of them and I've only put about 20 000km on my car since I've had it). Noise is piston noise, don't worry about it. They were bad for that too, mine also makes piston noise.

If the noise is loud, your crank is buggered, they were bad for that too.

posted by  88GrandPrixSE

The exhaust has looked normal -- I will check the smell next time I drive it.

There was a small coolant leak that I couldnt find so I used some of that aluminum sealant in it and it's been stable for over a month now.

the knock is seems to be consistant wether im reving it or not.

posted by  morningwood

I just edited my post as you posted that

Oh, you a corsica with the 3.1. Problem motors those 2.8's and 3.1's were. Chances are power loss is due to a blown head gasket (they were extremely bad for it, I've gone through 2 of them and I've only put about 20 000km on my car since I've had it). Noise is piston noise, don't worry about it. They were bad for that too, mine also makes piston noise.

If the noise is loud, your crank is buggered, they were bad for that too

If you couldn't find the leak, it could very well be a blown head gasket check colour and smell of exhaust, you could be in for a little work.

Knock is indeed just piston noise, it's not very loud right? Kind of subtle but still noticeable.

posted by  88GrandPrixSE

The knock sound could be subtle but it is defintly new, so I though I would bring it up.

I replaced my head gasket 40k ago is there any other symptoms I should be looking for as it wasnt fun :)

I went and checked the exhaust it had a heavy gasoline smell to it ( I dont know if this is normal or not as I never smelled it before)

posted by  morningwood

The exhaust isn't black? If it is, your O2 sensor might need replacing. When was the last time you replaced your plugs/wires?

haha, common symptoms with then really only included with the head gasket, is the exhaust and coolant loss (possibly over-heating also), keep an eye on your coolant, check if it's getting any lower. (If burning coolant exhaust is white) The smell might not be strong enough for someone without lots of experience to pick out if it's not burning too much. I'd put my money on your problem being the head gasket.

How many K does that motor have on it?

posted by  88GrandPrixSE

The exhaust would be clear if it wasnt 30 degrees right now

The coolant level has not dropped in the last month

The motor has 146k on it.

posted by  morningwood

Well, it's hard to tell what's wrong over the net, exhaust would be black if it was being over fueled or under-aired. Too much air wouldn't lead to a loss of power. Plugs shouldn't all of a sudden cause a drop in power so doubtful it's that simple. My suggestion, keep an eye on your coolant level to check if it goes down at all, or take it to a shop to have it scanned to check for any codes or maybe they'll be able to tell you right off the bat.

posted by  88GrandPrixSE

How right you were P0122 - throttle body injection sensor.

Ive replaced it and it now seems to be running better.

Thanks for your help

posted by  morningwood

No prob. Check engine light didn't come on for that? That's odd. That's good though, those things are known for their head gasket problem, and if the compression to coolant part of the gasket went, that causes a drastic loss in power (that's why I got my car, but, I just decided to blow the motor and slap a new one in, drove it till it died... left side head gasket.. Would've had to take apart half the motor, and the motor had 280k on it so it wasn't worth it.)

Did you scan it or did a shop do it for you that quick? Pretty good of the shop to do it for you on short notice like that if it was a shop.

posted by  88GrandPrixSE

hmmm what does a throttle body injection sensor have anything to do with what the other guy was saying? and i would love to know what a Throttle body injection sensor does?

posted by  BanffAutoSpa_ap

He probably mean't the Throttle position sensor or Idle Air Control. Not all people know everything about cars, just use your head and figure out for yourself what people mean.

I told him to get the car scanned and he did, that's what the posts had to do with eachother.

posted by  88GrandPrixSE

roger :thumbs:

posted by  BanffAutoSpa_ap

Sorry about the confusion, it was the Throttle Posistion Sensor(TPS) low input.

Unfortunately I was wrong in thinking it solved the problem I believe the car was just warm enough at the time I was replacing it as Im still getting the same code.

The autozones here will pull your codes for free it only took a couple mins to grab someone.

Right now it looks like a short issue of some sort anyone have suggestions on quickly tracing the issue?

posted by  morningwood

I have a 94 Corsica 3.1L. I'm having the same symptoms and its the crankshaft position sensor. The CPS going bad is also a common problem with this car I've heard. I'm having problems locating the sensor though. Any help/Pic would be useful since I can't find it in my repair book.

posted by  Russell

does this help

posted by  BanffAutoSpa_ap

Did you have the codes reset? If not, disconnect your battery for 30 minutes or so and then start the car back up, see if that helps. :2cents:

posted by  srober32

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