Cavilry

Hey all

Here in good ol' California I am having to smog my 1994 5.0L 5 speed and having a bit of trouble. Any quick ideas for what would cause an uneven idle? It is kicking the car out of the smog system. It seems to idle around 800 RPM but goes about 150 RPM to either side of that.

I have been checking for EVAP issues but can't track any down.

Thanks!

dawson1112

have you pulled any codes? Id say it has to be giving a check engine dropping to 150 rpm. Could be the egr valve is stuck open.

mattdel

does the car run fine other than that? i wouldn't think it would. the answer to this will narrow down the list of suspect failures.

Cavilry

Sorry, I wasn't very clear. It does not drop down to 150 RPM, it drops 150 RPM, to just above 600 RPM or so, and then goes up to just over 900RPM. There is no CEL normally, though it does sometimes come on briefly when on the freeway or under heavy acceleration.

The only other issue with the car (really the BIG, main issue) is that it has a very heavy vibration from about 2100 RPM to 2500 RPM and from about 3500 RPM up to ???. I thought this was something in the driveline, but it is now occurring in neutral or with the clutch in.

Thanks for the help you guys.

Tony71502

Pull the codes, it will help you alot.

Cavilry

Would the codes still show even when the light is not on?

Tony71502

Depending on the code, yes.

dawson1112

when that cel comes on it stores a code in the computer.
The vibration is most likely in the drive line even in N with the clutch in the drive shaft is still moving. Could be a bad u joint. Mine went bad but you couldnt tell till i took the drive shaft off and checked . the front ujoint was siezed up part way .

Tony71502

Does your driveline shake when sitting in neutral going 0 mph, if it does then it is something in front of the transmission.

Cavilry

Yeah, it is while sitting with the e-Brake on. So not going anywhere.

Harmonic Balancer? Engine mounts?