nathanUK '81 930 G50

The rev limiter is built into the rotor arm in the dizzy.

A930Rocket

I'm not sure if they all came with it or if was only certain years? Good idea to check though. It should cut out at 7200 rpm correct?

DDD

The rev limiter, IMO, is built into the Bosch CD box.

If you have a rev limiter in the rotor of the distributor, than this is something that was added by the previous owner. The rev limiting type rotor is an aftermarket rotor, and they can stick sometimes, although it usually will just cut out briefly like a misfire if that happens. I don't think that is your problem and I don't see why you would have a rev limiting rotor anyway because, again, I believe it is built into your CD box already.

I could be wrong and nathan could be right, but that is my understanding of the rev limiter situation for what it is worth.

And no, I have no clue about your problem. Sorry.

A930Rocket

I'm not saying it's right, but Pelican has them listed for our cars from 1976-1985.

930-602-901-01-M14 Ignition Rotor - Bosch, 911 Turbo (1976-85)
Brand: Bosch
$18

For the 86-89, they have a non-rev limiter rotor listed.

930-602-902-00-M14 Ignition Rotor - Bosch, 911SC (1978-83), 911 Turbo (1986-89)
Brand: Bosch
$6.00

pkrasusky

Thanks guys.

I too doubt it's limiter related as the sputter occurs at like 3k rpms and then irons itself out after I feather through it.

Learning alot though from all your responses, regardless. Great way to learn about these reading you guys. Again huge thanks for sharing your expertiseseses. If ya's gots any Audi //S-car related Q's I'm happy to oblige 8-).

-Paul
www.krasusky.photos.com

JBL930

I believe mine has the limiter in the rotor arm as standard, maybe it's a euro thing?

DDD

Or I am wrong. Which is a definite possibility.

As far as all the options that A930Rocket mentioned, I would add that they sell a lot of rotors for each version of the car in various catalogs, for instance I can buy a limit rotor or non-limit rotor for my 1976.

In my case, I know the 1976 has no rev limiter in the CD box, but I have read that starting in the late 70's or early 80's they went to a limiter right in the CD box.

But I could very well be wrong about the later cars, and Nathan could be correct. That would not surprise me at all...

And I don't think that pkra's problem has anything to do with this anyway. Sorry I can't help further.

nathanUK '81 930 G50

My car is a 1981 euro.

I bought a service kit last year or so & it came with the rev limiting rotor. It also came with the sump gaskets which I don't need as I have a later engine. My engine had the rev limiting one in it which I have now replaced with the new one. I must admit the service kit did not come from Porsche but it was from a UK specialist that I have used for many years without any issues unlike most, if not all of the others.

So, it would seem the later cars came with a different CDI that cut out at a certain RPM.

Paul, I think you should try temporarily grounding your overboost switch and see if the problem goes away. You must fit a boost gauge and watch out for boost spikes though.
Maybe you should just buy a new switch and be done with it.
I have an adjustable one I am going to fit in my 930

pkrasusky

Thanks Nathan-

I had a frozen waste gate when I bought the car a month ago and the overboost function was working fine - VIOLENT cutout @ 1.2bar. I replaced the WG and set my GReddy MBC to 0.8, which includes a boost guage.

The issue I have is a stuttering, misfiring, that comes up after decel from long time sustained high speed cruising, then you can feel it magically go away. It is not a violent cut out like a boost switch or rev limiter would be, just a 3k sputter that doesn't tolerate throttle input.

I'm kinda bummed, with all the expertise I've seen on this board when it happened I sorta shrugged and figued you guys would all be all over this and I'd be moving on by now 8-(.

C'mon guys, rise to the challenge 8-) (^^^^ meant to be a compliment btw not a dig!)...

-Paul
www.krasusky.photos.us.com

nathanUK '81 930 G50

Ground it and see.

srf506

A couple of last gasp thoughts, could the WUR be sticking or not functioning not allowing the fuel to flow properly after decel? There's a flapper in there and some other bits that could be giving you an issue with fuel delivery. The other thing is are the plugs and wires okay? Maybe one's shorting down/not firing under load. Other than that, I'm completely out of ideas.

Darn, its a lot easier diagnosing something when you can actually touch, hear and test things!


Jim P.

DDD

Try calling Stephen at Imagine Auto. 913-310-9927

Another great guy is Steve at rennsportsystems.com. 503-244-0990

Dave at TRE motorsports. 818-509-0257

These are guys that might have a clue.

We are just paid minimum wage to hijack your thread.

pkrasusky

Jim P. - a description such as that "feels" exactly like what it's doing. Any pointers on how to check the WUR? On that note <<<brandishes ignorance with pride>>>... I keep reading all these references to the "WUR" and figure it's something related to the fueling delivery - but - what does "WUR" stand for???

DDD, thanks for the references! And, hahahahaaha, totally.

srf506

Its the Warm Up Regulator and if you go to Pelican you can find what it looks like for your specific model of 911. If you do a search on these forums and on the Pelican technical BB I believe there's been a couple of descriptions on how to check them out. It generally looks like a valve body with some fuel lines in and out and I believe there's a vacuum line from a dashpot that goes to it too. Its on the top left of the engine IIRC. You'll probably need to remove the air filter to find it.

One last thought, (I keep thinking of these things in some haphazard, random way even I don't understand) but take a look at your injectors and their seals too. If one's leaking or sticking you might get a symptom like you describe.

Either Stephen or Steve are great guys always willing to lend a hand to us simpletons on this board. I'm sure they wouldn't mind trying to help you diagnose the issue.

L8R,
JP

pkrasusky

Thanks so much for the insight JP, I'll start the searches now. Much appreciated!

-Paul
www.krasusky.photos.us.com