Am having the strangest problem! I have an 88 GXL which has an s5 engine in it (done before I got it). Got most of the bugs worked out electrically except one. When I run over 3,000 rpms (worst between 3 to 4,000 and over 5, 000) the engine stutters violently, and tach goes wild only if the fan is on! If I turn the fan off, it runs great. I have a new battery, wires, plugs and alternator, have checked the coils per the factory repair manual and everything tests okay. Any ideas?

 

check the capacitor below the trailing coil packs for a good ground...the EMP from the fan motor might be messing with the ECU triggering signal to the coils...if that's good, make sure none of the fan wiring comes anywhere close to the coil wiring

 

Have gone through all the repair manuals I have and they show there is a capacitor, but do not show where it is. Can you describe where it is or what it looks like? Thanks.

 

Tell us how you've wired your fan.

 

Fan wiring is original - has not been touched.

 

I told you in the previous post of mine- it's below the trailing coil pack, just in front of the clutch master cylinder...get a flashlight, look UNDER the trailing coils, you should see a small black box bolted to ground- make sure the wire is not broken (or the ground dirty as heck)...Hell, check all your grounds in the engine bay while you're at it- that may be your prob...

 

So you're talking about the small auxiliary electric fan in fron of the A/C condensor? That should only run when the A/C is on or if the engine get really hot (206degF). It does not have manual control, so if you're switching it on and off then the wiring is not original.

The stock main cooling fan is not even electric, it's engine-driven, so if you're switching that one on and off then the wiring is definitely not original.

You need to tell us more about this fan.

 

umm yes is has because the stock fan has no wiring....