My N/A's top end (6000-8000 rpm) is quite rough, and it really loses power. There is also quite a bit of vibration up there (above 6k rpm). The car drives very nicely (though perhaps a little down on power?) up to about 6k rpm. It's got 166,000 miles on it.

What could be causing this?

Ignition?
6 ports? (would that cause the vibration?)
clogged cat (vibration?)

???!!

Thanks!,
Manolis

 

Ive been having the same nasty little hesistation right before redline on my 90 GTU. Ive been told its probably the TPS, but havent replaced it yet. Any other problems with your car, like a funky idle?

 

Hmm... I noticed that the idle was a _little_ rough, but not too bad...
When are the sixports supposed to open up? (it really starts to stumble at about 6K rpm, REAL smooth up until there...)

Thanks!,
Manolis

 

When i had my old stock motor, my car would'nt pull past 4,500. After lots of injector cleaner, the car would pull to 6k. But then fall flat on its face. What i did was pulled out the secondary injectors, and put 12vs to em. One of mine would'nt click open/closed. So i stuck a used on it there, and it ran perfect.

I don't know about your car adam, but my car drove so much smoother, after i had all 4 inj. cleaned. You might want to try that piston eater. With 160k miles on the clock, its probably time for it anyways. CJ

 

Ahha... it might be the injectors... (the could do it -- it _is_ pretty bad above 6K...)

any other ideas?

Thanks!,
manolis

 

I'm not sure but my FC does it also. I found some TII injectors that I *might* get to use as secondaries but I don't know if that's my problem. My car idles fine right at 750 so I don't think my tps is skrewy. My power drops off closer to 7k, it kinda fades.

I'm gonna be putting in a manual rack today so I might pick up some injector cleaner and try that. I've got 126k on my FC.

Piston Eater, is your vibration a total car shake? Check your wheel bearings, my car was getting a little squirelly (ugg too early to spell) at higher rpm's. Now there is no vibration at all after tightening the bearings.

 

I'll check the bearings -- chances are those could use tightening up as well, but the engine really drops off power and shakes at higher rpm (so much for rotary smoothness ).

Any suggestions for cleaning the injectors ? (soak in carb cleaner?, sandblasting:p , ??)

Thanks!,
Manolis

 

cool, so we can tighten the wheel bearings? i thought since they are imbedded in the hub you just had to grind out the old ones and throw in new ones...

 

Just about any auto parts store (i know napa does it.) or you can send it out to have it done. Should cost about $100 for the pair. CJ

 

I had the same problem before. I couldnt rev past 5K. It felt like I was hitting a wall. I Already had some 550cc secondaries coming in, so I dropped those in. They were kinda dirty, and didnt help much. I ran 2 bottles of injector cleaner through, and the car ran great.

But this doesnt feel like that did. That felt like hitting a brick wall, no power at all above when it first started. But Im only getting hesitation between 7500 and 8K. After 8K, my car pulls real hard to the rev limiter. I would really hope it is my problem, but Im not convinced F.I. cleaner will fix it. But I am still going to run a bottle or two through my tank this week.