Olds Achieva 3100 running rich

[iskerbibel]

I've got a 1996 olds Achieva, with the 3100 v6. It's running rich, gets bad gas mileage, and smokes black. It idles rough, but smooths out above idle. I've pulled the plugs, and they're all sooted real good. The fuel pressure is ok, and the pressure regulator is working right. I had Advance Autoparts plug their code reader in and check the codes. I get three codes: oxygen sensor voltage low on bank number 1 (do these have more than one oxygen sensor?), EGR valve pintle position, and a code for random misfire.

any suggestions?

[oleman]

Do not panic BUT
Those are the same codes I had with a blown head gaskit|s|. Coolent was leaking into the combustion chambers on 2 cylinders and being essentially burned.
It was losing coolent, about a pint a week, minor leak I did not find or put the engine miss with the leak! I thought it was the heater core causing the leak.
Later the coolent leaked enought to get into the oil. Before the coolent actually got into the oil it looked like an electrical problem that I was chaseing.
Engine only had 92K on it but was in bad shape requiring a rebore to repair.
RUN A COMPRESSION CHECK, that will tell you if a head gaskit is leaking. I never did because it is near impossible to access the sparkplug holes in the v6 front drive setup.
Bottom line is a $1200. rebuild, just for machining and parts, fixed the problem.
IF YOU ARE LOSING COOLENT, any at all, watch out.
If no coolent is missing it could be the O2 sensor bad, causing the engine to run in fail safe mode all the time.
If a head gaskit is leaking, the heads have to be resurfaced and new head bolts used or it will leak again.
Actually my machinest, said that the best way is to resurface the block (requires total rebuild) and the heads if you want some kind of assurance of good sealing heads.

[iskerbibel]

I took a look at the EGR, and the pintle was stuck up in the bore. I replaced it, and the car runs better, but still has problems. It still misses and smokes black. It doesn't use any coolant.

I'll do a compression check just in case. An oxygen sensor is kindof expensive- think maybe I could get away with cleaning it?

[grassulo]

clean and regap all your plugs, check your coolant temperature sensor, replace your o2 sensor, their really not that expensive, the one for my truck (which uses a 2.8 v6) was $25, check your manifold air flow or manifold air temperature sensor (depending on which your engine uses).

Basically it sounds like your car's ECM isn't getting information about air temperature, or is recieving faulty information telling it to run rich.

The missing you experienced may be due to the fact that you have sooty plugs, while you have them out, run a compression test on all 6 cylinders and check against the specs in your chilton's or haynes manual, if you dont have one of these definitely get one. report back to us with your results.

-Garret

p.s. Disconnect your battery while you perform any repairs or modifications to the engine, the computer stores the trouble codes and reverts to failsafe mode if any are in memory, so disconnecting the battery will clear them. If you have a security radio, be sure you have the code before disconnecting power!

[oleman]

Yes the O2 sensors, there are 2 of them, for the code M engine are expensive. I do not know what the recommended cleaning procedure would be. They are normally replaced.
I do not believe there would be a random miss code in the computer for a bad O2 sensor or temp sensor. Both of them have their own error codes.
I made the decision to keep my O2 sensors because the computer still says are good. I believe burning the coolent cleaned them up and made them work.
Since you are not using coolent, the gaskits are probably not leaking.
Make sure you use the proper AC sparkplugs, any other brand or temp is suspect.
Do the copression test when you replace the plugs.
Make sure you have good plug wires.
Make sure you do not have the sparkplugs cross/miswired.
When you make a repair, reset the trouble codes and recheck the computer. The ODBII systems will tell you alot.
I have a car to pc interface that lets me check codes and do other testing. Cost less than 100. at a br engineering BUT it did not diagnose a blown head gaskit|s|.
Other possible problems are: crankshaft position sensor, cam position sensor, ignition sensor (behind front dampner) coil driver module. All of these also have their own error codes.

[TheDirtyBen]

faulty injector(s)

[SHOoff]

I get three codes: oxygen sensor voltage low on bank number 1 (do these have more than one oxygen sensor?), EGR valve pintle position, and a code for random misfire.

Low output from O2 Sensor, Bank 1 Sensor 1. Yeah, you've got an O2 sensor, and you've got one behind your cat to measure emmissions. The front sensor shouldnt be too expensive. I just wouldnt reccomend using a bosch sensor. I've had problems with them not reading fast enough for some reason.

Random multi-cylinder misfire? That's probably just showing you that it's time for a little tune up. Plugs + wires should do the trick.

Make sure you use the proper AC sparkplugs, any other brand or temp is suspect.

I totally agree. My car always seemed to run better with the AC plugs.

Another thing to check. Since it normally gets put off. Battery cables. Make sure they're clean and making a good connection. Sometimes this helps throw codes. And from what i've noticed is when you throw a bunch of codes, it's normally just one thing that's wrong with it. (I had 13 codes set off cuz of a bad IAT sensor once)

Best thing to do is clear the codes, go out and drive it. And see which ones come back.