Engine trouble codes...GM style...

[trinacriabob]

I can't complain after 15 years and almost a quarter of a million miles. From another thread, I have to get either a tie rod or a front wheel bearing assembly fixed...but that can wait until early next week.

Now, I evidently have a sensor problem. For a while now, the SES light came and went intermittently and the only noticeable problem was a surge right after shifting into OD (4th) at relatively low rpms (1600 or so) and, right after shifting, if the engine is put under load. It was sort of a flat spot. Now the SES light is on "full time." Upon start-up, the 3800 revs up a little more than usual, idling is rough and the tach seems to wander (better with A/C on, which almost eliminates it) and it's running rich.

Sensors replaced:

within the last year or so, the O2 sensor

three years ago, the MAF sensor

Suspected culprits (based on reading some articles):

MAF Sensor

Idle Control Valve

Throttle Position Sensor

I had it in Saturday, he found a code that didn't need fixing (false read) and I have to bring it back.

But, there are smarter and more mechanically inclined people here than myself. Have you had this happen? What was it?

[Flybrian]

TPS or MAF sensor. I had a similar problem, vastly diff engines, but stil...

[loki]

could be an eaten gasket, or hose. ie vacuum leak.... my dad's '95 c1500 v6 had to have the T.B. gasket replaced cause one side it wasn't there...ethanol (the10%) ate it or just general deterioration. cause high idle normally, SES light on regularly, run horrible under ~1Krpm, it's a manual... does this sound familiar?

[76ChevyTrucker]

First check under the hood, look for the obvious, missing/broken hoses, loose electrical connections, after that. Buy a can of caburetor cleaner from your local auto parts store and begin at the throttle body base, with engine running, spray a little around the base area, if the idle smooths out like its supposed to, then you've got to replace the throttle body base gasket, do likewise with the intake manifold gakset. If at any point during the "test" the idle becomes smooth whilst spraying with carb cleaner, there's where your leak is.

[trinacriabob]

It was the knock sensor, which was Code 43, just like they told me at one of the auto parts stores where they will stick in the code analyzer for free. With parts, labor and the entry fee diagnostics, it was not cheap. Oh well, 3 sensors total in 15 years and no computer...yet...

I just want it to get to 250,000 and then roll it off a cliff...just kidding.

[76ChevyTrucker]

I knock sensor could do it, being as it would retard the timing to try to get the engine from pinging, even if it wasn't.

[Oracle of Delphi]

I think ocnblu sabotaged your car!

[trinacriabob]

I think ocnblu sabotaged your car!

You've got more to worry about...he lives a stone's throw from you...gated community and all...hehe

[Oracle of Delphi]

Meh, he's 70 miles from me, plus I don't seem to have the same affect on him as you do.

[trinacriabob]

Meh, he's 70 miles from me, plus I don't seem to have the same affect on him as you do.

Effect, the noun, is spelled with an "e." Va bene? :AH-HA_wink: