Hi all,

I have a 92 Magna TR sedan with two apparent problems:

1) It will occasionally blow smoke when iddling. This usually occurs when the car is warm and is more frequent when the AC is on. It does not happen all of the time - I had the car at the mechanics and he was not able to get it to blow smoke.

2) When iddling in Drive with the AC on the car will drop from 750 to 650-600 revs after about 30 seconds. Approximately 10 seconds later it will return to 750 revs. Sometimes it will repeat this drop and rise in revs. While 750 revs seems too low with the AC on, 650 is worse.

The car has a new iddle control and computer. Any ideas as to what the problem/s could be and possible solutions would be greatly appreciated.

Cheers.

1) Vavle stem seals possibly
2) That is bound to happen with ur air-con on if u get worried adjust the little thingy at the top of ur air intake to increase ur idling revs a bit (if u drive with ur air-con on alot)

4cyl or V6?
If V6, then pretty sure it's not just a matter of turning a knob for idle speed, as the ISC (Idle Speed Controller) will try to compensate for this. You need to actually turn off the ISC system before you can adjust it, and it's not as straight-forward as it sounds.
But I think, judging from the service manual, that you can do this with a 4cyl.

And yeah, first one may be valve stem seals, let it idle for a bit and then give it a rev. If a plume of smoke comes out, and doesn't smoke continuously when you are driving, then valve stem seals may be the culprit. But sometimes other things have the same or similar symptoms.

2) if it accompanies abit of bassy vibrations ie thermofans kicking in... your idle will move it usually rises i think though

Thanks everybody so far. It's a 4 cylinder sedan. How costly/difficult is it to have the valve stem seals replaced (if they are the problem)? The mechanic suggested that it could be the rings.

For a 4cyl, I think I've heard about $200 for valve stem seals to be replaced. A lot less hassle than on the V6.
The seals themselves are cheap, it's the labour involved.

Dunno about rings.

For a 4cyl, I think I've heard about $200 for valve stem seals to be replaced. A lot less hassle than on the V6.
The seals themselves are cheap, it's the labour involved.

Dunno about rings.
I paid $120 at mates rates, so $200 would be ok, wouldn't pay anymore than that though.

got mine done mates rates for a carton of woodys 440mL