weird symptons

[Lothurin]

Ok some history. 96 Corsica 3100 auto(duh), has about 147k. Plugs/wires were just changed around xmas, new Throttle position sensor, new maf.

The problem:

I'll start the car up either via autostart or manually, drive it around for about 10-15 minutes maybe less. Shut the car off and go do what were out to do. then come back and start the car either by autostart or manually. About 10-30 seconds of running the car will start stuttering like a have some huge big block cam in it. If I autostarted it, I usually shut it off asap when it starts doing this. If i'm in the car with the keys in, I'll give it gas to keep it going. Sometimes flooring the gas pedal, it may or may not do a little pop backfire. And I'll get a gas smell inside the car (more than likely flooded, but still running). I have no idea whats doing this, and its killing my back pocket. From the parts put into it and the 17 MPG i'm getting on the highway.


Since i know the time it happens i'll attempt to take a video on my iphone.

Hope someone out there can help me

Thanks,
Lothurin

[Bman Gtz]

I am thinking maybe a bad cat?

[3X00-Modified]

If it were a bad cat it would be constant and always the same, since it behaves differently when up to temperature I'm going to say look at the crank position sensor in the back of the block. Those will start to fail when warm and cause starting warm to be a bear, or run really bad.

Other things to look for would be a bad fuel injector once its warmed up, so I would ohm them all when cold and then after running Ohm them again see if one jumps up high. Last thing I can think of would be to do a ECU data log and see what the coolant temp sensor is reading, the dash reading may be correct but if its reading incorrectly to the ECU it will be making it run overly rich.

[ifixalot]

Are you losing coolant? A bad head gasket can cause a misfire after shutting the car off warm. The coolant pressure forces coolant into the cylinder and that or those cylinders misfire.
Otherwise, is there any other information you can provide?
SES light?
What do the plugs look like now?
17 mpg when the car is running good?

[scd88ga]

If it were a bad cat it would be constant and always the same

That is true for a plugged cat, but not true for a broken cat with pieces moving around on the inside. That could cause the sporadic systems he's having.

[3X00-Modified]

I had that happen but the broken front half clogged the rear second half which resulted in a slow steady decline of power and constant issues. Also his symptoms sound to be temperature related and affect it most on warm restarts.

[scd88ga]

I had that happen but the broken front half clogged the rear second half which resulted in a slow steady decline of power and constant issues.

Mine did the same thing and my idle and the sound of the car would change with the associated loss of power. But the pieces rattling around also made a heck of a racket! lol His problem is most likely sensor related though. Lothurin, you can always check the cat quick my jacking up the car and banging on the catalytic with your fist (when it's cold) and listen for rattling parts inside of it.

[scannerman]

Check your intake for fuel. You could have a bad fuel pressure regulator. The smelling fuel part makes me wonder.

[Lothurin]

well here is the first video i took just like 30 minutes or less

This one uses autostart

http://youtu.be/DZ7asQnocrM?hd=1


here is the second video after driving it a 10 more minutes after the first one

This one is manual start

http://youtu.be/GpbBiPDZQe8?hd=1


It was a lot faster doing this action. i'll take a few more vids as i can. I don't stop much between work and home.

I'll look into some of those other thing.

How hard is it on a obd2 3100 corsica if it don't have a cat on it? i don't want to throw all of my savings into getting this car running decent again.

[KFLO 93 GT]

Being a 96, it'd throw a code if it was having a major issue, so nothing has crapped out on consistent basis.

My thoughts revolve around an injector, icm starting to go out, or the previously mentioned CPS.

Something is either making it dump fuel, or not fire on every rotation leading to unburnt fuel and the gas you're smelling. Pre-cat O2 is something to think about given the poor mileage, but it should throw a code if it were shot.

[Lothurin]

yeah and this is throwing no code. Only lights i have on are low coolant (bad sensory not worth changing) and brake and abs light...i removed the fuse for abs, cause i couldn't stand the noise it made

[3X00-Modified]

You'd be surprised though, being 96 doesn't mean the code is even available to be thrown... The first gen OBDII systems were still lacking quite a bit, that's why I went from the 96 ecu to the 97... I'd love to be running a 2000+ one though.

Back on topic that sounds like you have a really big VAC leak somewhere and the IAC is trying to recover from an over idle condition and it over compensates almost choking the engine... See if you can have someone throw a scanner on it and read some of the sensor values...

[Lothurin]

When you talk about a 2000+ ecu is that any 3100/3400/3500 or does it need to be out of a specific car? Also, other than installing it anything else required?

[3X00-Modified]

I am referring to a 2000+ ecu out of a grand am or something that ran a similar trans to what I have... You can not interchange these without major re-pinning of the harness though. The only one that's a direct plug in swap is the 97 venture, but even that has to have some things done to the file so you wont throw any codes.

Bottom line you have a mechanical issue somewhere with VAC or idle control, so I would start researching those areas first, and the best way to do that is hook it up to a scanner and see if the MAP sensor and such are reading properly and not just stuck steady somewhere.

[Lothurin]

Rofl. Almost be cheaper to borrow a used helmet and smack a tree at 40mph

Thanks for all the good advice. Now to find some cash.