Hi there, I'm hoping someone will have some ideas ...

We have a 2002 Monte Carlo SS 3.8 with 216,000 miles on it. 2 days ago it wouldn't start, with no symptoms leading up to that. (Other than some roughness that I attributed to putting cheap gas in it) It would turn over but not catch, with the smell of gas everywhere. It was acting flooded. Checked relays, spark, etc, nothing wrong with those. (spark was weak though)

The next morning I was able to get it started finally, with lots of smoke and sputtering. I had to put it in neutral and rev it, then quickly put it in drive and go. By the time I got to the mechanic it had smoothed out somewhat. He checked it and said the computer said mass air flow sensor, so he replaced it.

It starts up and stays running, but still running rough: still skipping, and rpm's are jumping all over even when going at a steady speed. Running it on the highway in cruise it does the best. It protests speeding up (like getting on the highway)

Sunday I washed the engine with the garden hose; a sprayer nozzle was on it. The next day my abs light and trac control light kept going on and off and I couldn't figure out why. The day after that was when it wouldn't start. The mechanic thinks the water might have damaged something, but I've washed my engine before and never had a problem. (I was trying to find the source of an oil leak) He's really not sure why it's still running bad. Spark plugs and wires have gone 100,000 miles so definitely due. All sensors (except maf) are original, most parts are too.

Any thoughts?

Thanks!!

 

Pull the hose off the FPR and smell it. If it's wet or smells like gas the FPR could be bad.

Since the car is so old, you really need to just start with the basic tune-up stuff. Fuel Filter, Plugs, Wires, etc

Pull the IAC off the TB and clean it up a little, could be caking up with carbon.

 

Hey, thanks!

Another question: pulled off the IAC and it was filthy. Cleaned it up with throttle body cleaner and now it's running worse. Sort of unsure where to go from here; I keep throwing money at it (replaced fuel filter few days ago, no difference).

 

Ok, so now we have: replaced the iac valve entirely, nothing. Took back to mechanic and he ran the computer on it and said bad tps. Changed out tps. Still running exactly the same.

How common is it to get a bad tps? (Aftermarket, brand was BWD)

Any other ideas? Should I just take it to Chevy to diagnose? Our mechanic ran a complete computer scan, we have compression in each cylinder. Just completely flummoxed.

 

Perhaps the wiring is bad?

 

That's a good point; it would explain why we can't seem to get to the root of the problem. And this morning the battery was dead! (fairly new battery, only about 6 months old)

 

Check the 5v reference circuit and make sure it isn't shorted to 12v.

 

Just to clarify:

When you replaced the MAF,... Did you replace it with a "NEW" or "USED" MAF?.

Maybe..u got a bad 1?

Try un plugging the MAF...then start and drive it....with it unplugged...
If....it runs better...Could be the MAF is bad...

Just a thought...

Id be curious what you find out...or what the fix was....

 

My husband and I are stumped on the 5v reference circuit. Can you explain a little more? We REALLY appreciate all the input. Exchanging the tps today on the off chance we got a bad part, going to try disconnecting MAF, doing plugs/wires this weekend too.

 

Oh, and to answer your question, the MAF was new, but oddly enough the mechanic said the first one he got was bad so he had to get another.