Another problem

[Slowpoke59]

1991 DX. So 2 days ago I was driving home and the check engine light went on for a second and the engine stumbled. I thought "Huh". Went off for about 10 seconds then came back on and stayed on. And the engine started running really rough. Not a good sign just a week before a really long trip.

By the time I got home it was really running bad. Wouldn't idle half the time. And grey smoke out the tailpipe.

Pulled a code, it said 17. Looked to see if there was anything obvious in the engine compartment, but didn't see anything wrong. Did see that it was the original O2 sensor, so I bought a new one and put it in. Started it up, and seemed to run fine.

Next day, driving to work, about 15 minutes into my drive it did it again. Pretty much the same things.

Don't have a lot of time for diagnosis, So starting to replace things one by one. Ordered a new water temp sensor last night, will pick it up today after work. And yes, I think I ordered the right one. It's the 2 wire one on the right side of the dist.

Anyone have any pointers on what else could be wrong? What to check for, or what might be failing?

Thanks in advance.

[1LordAnubis]

Hmm... the only time I ever had the check engine light come on was for the o2 sensor. As for running rough, I would first check spark plugs. I hate to say it but grey smoke means water getting burned off, worst case it'd be a headgasket.

[Slowpoke59]

Put in new plugs, cap, and rotor 2 weeks ago. Was running great after that until now. As for water in the combustion chamber, wouldn't that be white smoke?

Update. Went to work this morning, and also drove back home. Roughly 22 miles each way. No hint of CEL or rough running yet. (Keeping fingers crossed)>

[Msptothemax]

Gray smoke could also indicate raw fuel ie: injector stuck open which is going to feel similar to a misfire or cause the spark plug to burn up...

[me109]

Coolant temperature sensor seems likely. Crappy idle when it's warm, right? It goes away by the next morning? And it hasn't happened since you changed it. The only counterindicator I can see for it is the lack of a code 09, but these OBD systems are not 100% accurate either. Either way, hopefully you fixed it already.

[Slowpoke59]

Coolant temperature sensor seems likely. Crappy idle when it's warm, right? It goes away by the next morning? And it hasn't happened since you changed it. The only counterindicator I can see for it is the lack of a code 09, but these OBD systems are not 100% accurate either. Either way, hopefully you fixed it already.

Yes on the first part. Have the sensor, but don't have the time yet. Maybe Sunday.

Will let you all know.

[jay]

Yeah grey smoke isn't head gasket, it's fuel.

[xmaster19]

I have a similar problem on my gtx, also it stutters at a certain rpm, I can see the tech needle miss a beat also so I'm suspecting coil power or ground.