Ok, here the problem. I purchased the car from a friend about 3 months ago. In that time I had to do some minor work such as replace the AFPR, do some rewiring to the fans, replace the distributor cap, new plugs wires and so on. This car had not been run for the better part of three years until I bought it. It idles smooth and runs very strong except when the tach is right around 2k. At this point the engine feels rough, almost shaking. If I exceed 2,200 or so it's smooth...as well as below about 1,900. This shaking is pretty bad at 2K and occurs hot or cold. The whole car shakes with the engine. Any ideas what would cause a problem in this range? Any suggestions would be very appreciated.

 

I'm wondering if its a fuel pressure issue maybe. Don't think an ignition module would cause that. What are the motor specs? carbed or injected? etc. Are you throwing any codes? Vac leak maybe?

 

5.7 TPI is the engine. I don't have anything to check codes with, which is why I'm kind of asking around. I know this is going to sound pretty bad, but how do you check for vacuum leaks? I am very new to working on cars, especially V8's.

 

keys and a paper clip for the codes.

As for the vac leak. I would recommend replacing anything that looks suspicous like cracked and split lines. I've heard of people spraying solvent or WD-40 on the lines but this doesn't always work. It will give you a start though. Sometimes you can hear the leaks if they are bad enough!

This will help you with the codes and what they mean. The diagram below shows where to put the 2 ends of the clip. turn the car on SES light will blink 3 times (I think, haven't done this in a while....someone correct me If I'm wrong) then count the codes that follow.

http://216.121.161.76/files/GMError.pdf

 

Thanks a lot...that should be helpful. I know there are articles about the paper clip deal in the archives so I will go there for that. Thanks again!

 

I would download adobe acrobat reader for the file I put above. This gives all the codes and what they mean. Could be very useful for later on.

 

Been looking at it already. I also read up on how to check codes with the paper clip. Now if I could just go outside of work for a minute and try it out! Thanks for the *.pdf.

 

no prob. Good luck. Don't get stuck on one idea though. It could still be something like the ignition module, coil, or FPR. Don't discount these.

Brian

 

hmm im sort of having that same problem. and thought that maybe it was the ignition coil. because it has a high and a low rpm function. and i was wondering if it could be screwing up going between the two or whatever..