Dash01

A friend's '86 951 starts and idles OK, but won't rev more than 3,000 RPM.

What would account for this?

NeedPorscheSpeed

Awww man!!! I was thinking that you had your car running again...
Revving to 3K would have been better than not at all, I thought.

As to what is causing the car to hit a ceiling at 3K, maybe there is far too much slack in the accelerator cable? I'm sure that's something that you've checked, but that is the first thing that comes to mind.

Dash01

Actually, my car still is not running--won't start due to bad DME.

My non-Rennlist friend (in another state) has another '86 951 that starts and idles OK but won't rev over 3,000 RPM. He cannot find the reason, so I posted here for him. Any ideas why his car has such a rev limitation? Is it likely his DME?

fast951

Have your friend try few basic things then post the results here.. All it takes is fuel/air and ignition to fire the car..

- Have him try revving the car fromthe engine bay by opening the Throttle plate by hand
- Check the TPS make sure it's aligned & functioning correctly

Following tests while revving the car idle-up..
- If he has a fuel pressure gauge, check the fuel pressure all along the RPM band (up to 3000rpmp??)
- If no gauge, have someone else check the color of the exhaust when he revs the car (dense black?) RICH
- Is there any backfire (intake backfire)? LEAN
- Pull one spark plug, report the colr of the tip....
- Pull the distributor cap off, check for cracks, check the rotor...

Again, these are basic things to check.. At least we might have an indication of what's causing the car to shut down (Air, Fuel or spark).

Ken

Fast951 is spot on. I personally would check the TPS(Throttle position sensor) first.

Gator_86_951

Same thing happened to me recently. Two people putting the intake system back together without communicating properly left large blue shop rag in j-boot. The rag sat right in front of the turbo compressor. Pretty funny. We spent all day checking everything only to find this when we finally took those back apart. Well, at least I know everything else on the car is in working order.

JustinL

You can unplug the throttle position switch. IIRC it's a square electrical connection on the throttle body. This will force it out of "idle mode" and let it rev up over 3000RPM. This happened to me a long time ago... and my memmory is a little foggy on the issue so I'm sorry if this is a little vague. I also seem to remember that the click from the throttle position switch was gone when you move the throttle plate from closed.

Dash01

Re: Car won't rev over 3,000 rpm

Any other ideas?

Could this possibly be a DME fault?

alexands

What happened to me is that the potentiometer in the AFM got bent a little so it wasn't making good contact. Apparently, the PO had been in there monkeying around. It cut out around 5K RPM. I just had to bend the contact back in place. If no one has been in there this shouldn't be a problem. Just thought I'd throw it out as another possibility.

hosrom_951

This MAY sound silly but it worked for me once.

After cleaning the engine, started the car and it would't rev over 2,000rpm.

I disconnected the reference sensors, cleaned then, dried then and re-connected them the car worked fine.......try that?

theedge

On the rubber thing that connects the IC outlet pipe to the TB, theres the hose clamp. Check where that is, I put mine rotated too far once, it would stop the throttle from opening at all, freaked me out when I started and tried to rev, the pedal wouldnt move at all

This is prolly discounted if he can put the pedal to floor yet it stops at 3k rpm...

Re-animator

Same thing just happened to me. A little bending and electro-conductivity helper spray and all is well. Just posting here, so you know your post helped at least one person. Thanks.

Dal Heger

Replace the TPS.

Typical failure mode.

Dal.