jerryjfunk

I drive a 93' Buick Riviera. It's ran great up until yesterday. I changed the oil (which I do every 3,000 using Castrol Syntec), put some injector cleaner in the gas tank, and replaced two vaccum hoses.

I started it up, it ran fine for a few seconds, and then as it approached idle speed, it started running weird. It sounds like it's going to stall, but doesn't... almost like it's running out of gas, or maybe running on 5 cylinders. However, I just replaced the plugs and wires a few months ago, and it had a half tank of gas, 91 octane. Oh, I also replaced the fuel pump, filter, and in-tank filter at the time that I did the wires.

I thought this might be an electrical problem, maybe the throttle position sensor or something. I was messing around with it with the engine running, pushing it back and forth. The engine seemed to run a little smoother when I pushed the lever up a little bit, but it still wasn't right. I then tested the computer codes, and it came up with 2 codes: 21 and 22, which are TPS voltage too high, and TPS voltage too low. I chalked that up to me pushing the lever by hand. I cleared the codes, ran the car again, then tested it. It came up with no codes.

I drove it to work tonight... it still idles horribly, just barely running, the lights flicker and everything. But while moving it seems to run ok, although not as smooth as usual.

What do you guys think? :confused: I'd appreciate any help!

Thanks,
Jerry :D

LAvetteman

Look for a loose electrical connection somewhere around where you were working.

Madmikeee

that, and also consider that one of your injectors MAY be clogged

jerryjfunk

I realize that it's easy to make a mistake like switching hoses or wires, but these are just short pieces connected to hard lines. I know for a fact that they are on right, and that I didn't mistakenly disconnect anything else.

I did just discover that the engine runs better when I disconnect the wires from the... air sensor, I think? It's plugged into a small box on the intake. I checked my filter, it still looks new, and there doesn't seem to be dirt in the air box. I'll replace the sensor and see if it solves the problem.


I DO wonder about the injectors, though... maybe my top end is also suffering but I don't realize it. I'll look into it. :yesnod:

Thanks,
Jerry

burners

It could be the IAC, Idle Air Control solenoid. Sometime they die but mostly they just clog up. Get a can of carb cleaner and spray down the back side of the throttle body. Keep spraying until it and the surrounding area is clean. If the IAC is plugged then the idle will be erradic. Don't run the engine for a while. At least until the cleaner evaporates. The procedure should be a regular maintenance item performed once a year.

Colin

Hit the IAC with a screwdriver handle. If the car starts idling normal, replace the IAC.
Same with the TPS.
Although I doubt both failed. The poor idle sounds like IAC, but with it throwing TPS codes I can't tell.
If you have a service manual and a multimeter check the TPS and IAC. If they're out of spec, replace.

Colin

Jvette73

Although you didnt mention doin it, sometimes people spray carb cleaner on the throttle body to clean the gum off. When this is done it can foul the oxygen sensor and cause problems.

4rensic22

Check for a loose sensor also.

robert kirk

Jvette73 is right. ask me how i know, go ahead ask me, i'll save you the post, a hundred dollars and 2 oxygen sensors later i figured this out all by my lonesome. learning curves can be harsh sometimes. robert

jerryjfunk

Thanks for all the help, guys, I really appreciate it. It must be the IAC that's broken. For now I have it unplugged, and have to put up with the check engine light. Next paycheck I'll replace it (spending all of this week's money on the Vette, of course). :D

Thanks!
Jerry