I recently acquired an '89 GTU with a manual tranny and without an engine. I had an engine from a '90 GXL automatic with good compression, so I dropped that into the '89. Everything seemed to go really well except for one problem. I now have a hesitation @6500 rpm. Actually, it's more like hitting a rev limiter. The car stops accelerating and slowly drops in power until I back off and ease back into the thottle. This is very consistent and happens near or at wide open throttle around 6.5k in gears 1, 2, and 3 (I haven't tried 4th or 5th). I haven't really done any troubleshooting yet and I wanted to get opinions first. Tommorow, I'll be doing the usual things like tps and timing adustment and fuel filter replacement. I don't think there are any vaccum leaks as I have checked and or replaced all of the hoses. The car idles and drives very well with the exception of this problem. I'm leaning towards a grounding issue. What do you guys think? I'm hoping to have this fixed by Sunday for the autox.

 

Throw a timing light on a car and see if spark dies at 6500.

 

check the vdi and 6-ports if they arent engaging properly, especialy the vdi, power will realy fall off in the uper revs. if the engine will rev all the way to 8k in neutral but just makes no power this could be the problem if you cant even get past 6.5k i dont know what to tell you but good luck anyways

 

I should have mentioned that I wired open the aux ports as a test today. The same problem existed. I haven't tried the VDI actuator, but I'll give it a shot.