My '88 LeSabre (145K) vin code 3, 3.8L always cranks 3 or 4 revolutions before it starts. When it does start (it always does) it races to maybe-2000 rpm then idles down to a normal idle speed). I bought this car a year ago from a shop that had given up on ever getting it running. After doodling around with it for a while, I discovered It needed a new cam interrupter magnet. After I got it running, I put in a new O2 sensor.

I get no check engine light, and the resistances on the IAC are within spec. I noticed the IAC was not perfectly tight on its gasket, and tightening it up makes the too fast idle come down more quickly now, but it still races when it starts up. I hate this. I just think of how damaging this is to the engine to run fast before the oil pressure is up.

The car also is getting pretty crummy mileage 16.3! Yesterday, I removed the throttle body and cleaned it with a toothbrush and carb cleaner, removed the IAC and cleaned it and the passages from it, but no change in the fast initial idle or cranking or crappy mileage.

Any ideas?

:?:

These GM 3.8'* run up high on idle, especially in the cold. Mine goes a little higher then 1500 rpms, then drops down after 10 seconds as well. Then mine steps down to 1000 rpms, then to normal idle.

Check for a vacuum leak on the fitting on top of the throttle body. It has a bolt that goes through it which then squeezes the fitting in place. In my 90 Lesabre I noticed the fitting had moved a bit, repositioning it cured a whole bunch of evils.

Cheers,

Yeah, Foghorn, I just had that fitting apart yesterday, mine has two machine screws holding it in place. The gasket appeared OK, but a leak may still be possible there. Maybe if I start it up and spray some WD-40 around the base of the plastic fitting, it would reveal by change in idle if it is leaking.

The car also has new air filter and platinum plugs, and I checked the fuel rail pressure after it had set for a while to see if maybe the fuel pressure regulator was allowing the rail pressure to drop indicating a bum diaphragm, but I got a pretty good squirt out of the rail when I depressed the shrade valve. The car is dependable enough, it just ain't quite right.