Motor cutting out when transmission engaged?

[Newlin4141]

Wondering if this has ever happened to anyone...

I have a 1980 930 with a 3.2L from a 1986 donor. Very recent problem has developed: The motor starts up and idols as you'd expect, but when the transmission is engaged in any gear, it's like there's a governor on the motor and it cuts out completely at about 2,000 RPMs. There's no feeling of the clutch slipping, nor does the motor seem to behave differently when not in gear. And I don't even have a rev-limiter, so that can't be it (plus it revs fine if not in gear).

Anyone experience anything like this? I searched the Pelican forums and can't find anything. Maybe I'm not using the right key words.

[porsche930dude]

perhaps something with the cruise control is my guess

[Newlin4141]

Cruise control or rev-limiter would make sense, but the car doesn't have either of those features. Very odd.

[Neilnaz]

So you dip the clutch and put the car in (any) gear and the engine dies?

If that is the case could it be that the clutch is not (totally) disengaging?

Just a thought...

Neil

[Newlin4141]

Thanks for the post.

No, the car sort of lurches back and forth for a second when RPMs get past 2k, then the motor goes silent and would presumably die if I didn't let off the throttle. But as soon as I let off the gas it recovers.

If I gradually let off the clutch while applying very little throttle then don't accelerate – effectively letting the motor's idol-level of fuel input move the car forward, much like how you'd put an automatic transmission into Drive and could take your foot off the pedals – the car would just putt down the road.

[Neilnaz]

OK so the clutch feels normal then? You have no doubt about its action? Clutch in whilst in gear is the same as clutch out in neutral i.e. the clutch is totally disengaging the gearbox when clutch pedal depressed.

If this is not associated with clutch/drivetrain then I am stumped.

I would suggest trying to describe in detail the behaviour exhibited by the car so people with far more expertise than I can help diagnose for you. No criticism intended but it isn't (totally) clear what is happening in exactly what circumstance to enable an understanding of what the problem could be.

I wish you the best of luck.

Regards, Neil

[Hil911]

Dumb suggestion, but it doesn't have a security system with a valet setting, does it?

[JohnJL]

Can you rev the motor in neutral? The distributor advance isnt stuck? Did this start all of a sudde , or after some work on the car?

[rick-l]

Sounds like a fuel supply issue. I know nothing about CIS cars however.

[CCM911]

Is the emergency brake frozen? If the car is in gear with the clutch engaged, can you rev it out like normal?

[Quicksilver]

Is the car still CIS or did it go Motronic with the engine swap?

[T77911S]

more info is needed about the setup.

3.2? 3.3 was the turbo motor. 3.2 is non turbo.
injection system? motronic or CIS
is the 3.2 turbo?


first thing is check for air leaks since we really have no info on the car.

[Newlin4141]

Thanks for all the questions and feedback. And sorry for the murky description, it's a really strange thing.

The clutch feels totally normal. And I haven't had any work done on the car recently. When I drove it to get coffee yesterday, it was fine. When I left the coffee shop, it would not rev beyond 2k while in any gear. When the clutch is depressed with the car in gear or if the car is in neutral, it revs fine.

When I put it in first, rev up the RPMs and ease out the clutch, the motor starts cutting out and the car begins to lurch back and forth. So I push in the clutch and take off at a very low RPM. If I shift to second the car will actually move faster (because second gear is obviously taller than first gear), but the motor still won't go past 2k RPMs, regardless what gear it's in.

More background on the car: It has a motronic ignitions system, there's no security system, cruise control or rev-limiter on the car.

The motor in the car is a 3.2L non-turbo from a 1986 911 Carrera (so not the original). It's been a great motor (although a bit anemic relative to the original 3.3L Turbo which is being rebuilt).

I'm guessing it's a fuel delivery issue or possibly something with the e-brake. I had to relocate the e-brake a couple years ago to make room for a new shifter. I just went out and checked and the e-brake light didn't come on when it was engaged at first with the engine running. But it eventually came on after releasing the e-break and re-engaging. So that's a little odd.

Whole thing has me stumped.

[Newlin4141]

Just checked for loose connections or anything obvious with the e-brake. Can't seem to find anything, though noticed something else:

The car idols fine. But now it cuts out when it's in neutral and I blip the throttle with the e-brake on or off, which is different from yesterday. Same for when it's in gear with the clutch depressed. The car sputters between 2 and 3k RPMs for a second, then gets past it and comes to life and sounds normal past 3.5 or 4k RPMs.

Don't know if this matters, but when I blip the throttle from within the engine bay (verses from the pedal within the cockpit), the motor seems more responsive and revs quicker.

I'm not as mechanically proficient as I wish I were, especially in times like these.
–John

[rick-l]

The 3.2 has a test port for fuel pressure on the drivers side fuel rail,

[DRACO A5OG]

Originally Posted by Newlin4141

Don't know if this matters, but when I blip the throttle from within the engine bay (verses from the pedal within the cockpit), the motor seems more responsive and revs quicker.

–John

Brother John,

Disconnect the throttle linkage at the bell housing ( Gear Box ) then see if there is any binding fore and aft. Make sure nothing is obstructing the pedal path and nothing near the throttle body. Check for smooth movement. If it binds you may have found your culprit.

Jim

[gtc]

It kinda sounds like something is happening in your pedals or tunnel.
Does it cut out now if you open the throttle at the throttle body?

[Hil911]

I lost it somewhere but are you saying that the engine dies under load? It's not really whether it is in gear or not.

My car did that when the ignition was not sparking properly. Fine on idle and low RPM but unable to push the car above 70 MPH.

[cabmandone]

I'm gonna throw this out there, Your cylinder head temp sensor went bad or somehow got unplugged. The car will idle and throttle up but under load falls flat. My car did that exact same thing when I bumped my CHTS wire off in the engine compartment. Another good possibility is you have a old fuel filter and when the engine is placed under a load can't supply sufficient fuel to the injectors.

I'll add more about how my car behaved and you tell me if yours sounds the same. I could start the car and it would idle somewhat normally. If I blipped the throttle it wold rev but was a little sluggish. When I put it in gear it would stall or cough and I'd have to take it out of gear and really play with the throttle to get it to stay running. Once I kept it running and it settled down it would idle relatively fine again.

[E Sully]

I would also check the flywheel sensors to make sure the gap is correct. There is also a chance of the track being worn in the air flow sensor.
Air Flow Meter (AFM) - from "The 944 Motronic DME" by FR Wilk* ©2001 www.the944.com