Need a little help here on an issue I am having with my 1992 Z28, Heritage Edition, with the 5.0 L and 5 speed manual transmission. While driving the car in either 3rd or 4th gear and running constant between 1500 and 1800 RPM, the engine sometimes misses or shows a small hesitation. The car never quits or stalls, but you can definitely feel a jerking motion or a slowing down, like the car wants to stall. The car has good acceleration, starts just fine and also idles fine. This issue only happens when in that RPM range (1500-1800). If going above 1800 RPM there is no hesitation. I have replaced the plugs and the coil as well. This did not resolve the issue. Any suggestions as to what the issue might be. Thanks.

 

There are a lot of things that can cause this. Step one would be to watch the O2 sensors output while it was happening. That would give you and Idea if its fuel or spark. It could also be a vacuum issue a jumping timing chain or a weak EGR valve. Keep in mind this is why there is a Class A level tech. At some point is the late 80s driveablily experts past automatic trans techs in pay.

 

Thanks for the input. I will try some of these and see if there are any good results. The mechanic I use said the same thing. It is hard to determine issues like this before ODE II, and specifically in a manual trans car. He had also suggested the same items to be looked at or replaced.