A simple way to eliminate those things would to simply figure out if its an ignition related problem.. when its stumbling see if you still have a strong spark.

 

Dale, ICM was swapped with the one I have in my 93 Blazer. No change. Yes, the pickup coil is rusty. As soon as the rain stops here (rainy season) I will take some readings on the picku coil. Thanks again for the input.

 

89RsPower, I will take a vacuum reading from the EGR the next time I run it. Let me know what you all think about the following statement from a Japanese car shop: "TPI engines start idling rough and erratic when they are in need of a rebuild (i.e. piston rings)". Again, this is coming from a Japanese owned American Car shop. Just for the heck of it, I am going to do a compression test sometime this week.

 

thats a first i have heard of that...if you want conformation on that this would be the place to find it. try a search on it.

 

I didn't mean actually take a vaccum reading, I just ment remove the vacc supply line from the valve to see if it effects the stumbling at all. Just pull it off for a sec. I'd stay far away from that shop as that makes no sense at all. I just pulled a worn 305 with tpi out of my 89 that ran perfect other than the low oil pressure, rock knock, and blow by from the rings. What you are experiencing doesn't sound like it has anything to do with a worn out engine.

 

Got you, I will try that today. Finally have a clear day without rain. Yeah, I had a hard time believing that the engine missing and idle problems would be caused by a worn out engine. Granted, this car has been abused (as all American cars over here have been) I found it hard to believe that the engine, with only 64k, would need a rebuild. When I pulled the plugs it had "0" oil or carbon buildup. Thanks again 89RsPower!

 

89RsPower, I just started the car and removed the vacuum supply from the EGR. There is no vacuum at all at the EGR valve. I put my finger over the hose end and also listened but couldn't hear or feel any vacuum. Also removed the vacuum line coming from the underside of the throttle body... again "0" vacuum. The inside of the upper intake plenum looks like tar inside.. quite possible that it's blocked with dirt. Also took resistance readings on the pickup coil and it reads correct.

 

At Idle, my line that comes from the bottom of the TB has no suction. It doesnt get any tell you crack the throttle. But thats mine.

 

Dale, you're right. I had a friend come over today that's a gas turbine mechanic/automotive mechanic. He says it shouldn't build any vacuum pressure until you accelerate or open the throttle. After more analysis, he believes that my distributor is bad. There is a very slight wobble to the rotation.

 

the egr valve will only receive vaccum when its commanded on. No vaccum is normal when it isn't. So the car was stumbling like normal but the egr valve wasn't receiving any vaccum?

 

Have to bring this thread back, what happened?