Fred, Long Island

Just a thought....The resonance flapper...is it being told to activate, letting in required air for the revving? The DME is charged with telling this unit what to do.

Mark Brook

Fred,
This flapper, is it between the airbox and the airf flow meter ?

DougB

The throttle valve is the only way to increase the revs this much. No injectors, fuel pump, ICV or anything else can cause this.

You should be checking the throttle plates. Your car has 2 of them--a small primary and a larger secondary. You may have an issue with the complex linkage connecting the secondary plate. It may even be disconnected.

-doug

Wachuko

Can you replace de DME as a starting point? Cheap to replace and easy to do yourself. That will rule out that.

John Boggiano

Jamie means the DME 'Relay', of course - not the actual DME.

Adrian

Dear Mark,
The problem is air related. The DME cannot provide the fuel unless it is getting the air.
This happened to me once and it was the throttle valve itself frozen open. Now this is not your exact problem but something is opening the throttle valve.
If the air flow sensor is stuck open but the airflow is not actually increased the engine will stall due to excess fuel in the air.
So we have to start with the obvious, the throttle linkage under the pedal.
Do you have cruise control? The engine drive unit can cause this problem.
I am afraid the only way to check is to start at the beginning accelerator pedal and work your way back to the engine.
Keep in mind always that to have 6000 rpm you have to have 6000 rpms worth of air AND 6000 rpms worth of fuel. The DME only provides the fuel, your foot provides the air.
Ciao,
Adrian
964C4

Flyin Elvis

I'm gonna take a stab and suggest that you may have disrupted something when you moved/checked airbox. I saw an earlier car that lost a small clip on the throttle cable in the engine compartment next to airbox and pretty much the same condition revs through the roof. Was the cruise control operative recently? The first problem could be a ground but I don't know where to tell you to check other than Adrians book or a qualified tech. As above, don't drive it again but, in neutral with ebrake on how does the thottle function? Best of luck.

Flyin Elvis

Mark, As I was typing my last post (along with taking calls) Adrian posted with the expert advice show should follow. We are soooo lucky to have these guys to help. Good luck!

Mark Brook

Thanks for reading this thread guys. The throttle peddle action is ok. I've taken the mats up, removed the wooded floor board, cleaned out the dirt (plenty of it.) , and all seems in order. Turned the car over and the revvs shot round again, so I can discount the peddle out.
The air filter box is still installed, no holes drilled etc. The only thing that looks amiss is where the air box is secured to the inlet pipe thingy. The plastic has snapped, and can be moved around by hand. It has about 5 mm of movement.
Adrian, from your book p139, I have the 1989 WOT. Should I source a replacement ? The electrical conections look secure but I'm no expert. Should I take things to pieces from the airbox back?
The throttle body and springs seem fine. I had a new Aif Flow Meter last summer, along with O2 sensor to rectify poor idle.

Thanks again fella's,

Mark 90C2
p.s. Adrian, my car was delivered new on 17/10/89, but I read that C2's weren't delivered until 1990. Is this a bit odd ???

Mark Brook

Oh, and I have no cruise control fitted.......

Adrian

Dear Mark,
You are cofusing model year with calendar year. Yours is a 1990 model. There is no such thing as a 1989 model year C2.
You have an open air intake. It is getting too much air in. I suspect that the throttle valve is stuck wide open. I cannot advise you any further until you have checked the position of the throttle valve. I am certainly not going to advise new parts until you have found a problem.
The WOT tells the DME that the pedal is flat to the floor BUT that will only give you more fuel which technically should stall the engine.
I would be checking how much actual movement you have at the throttle quadrant. Move the quadrant by hand (engine off) backwards and forwards a few times.
On my old 944 I had a similar problem and it was the cable end which had come adrift effectively locking the cable at 3000 rpm. However when you looked at it this could not be easily seen.
Ciao,
Adrian
964C4

Mark Brook

Adrian,
By quadrant, you mean where the accelerator cable meets the inlet body ?
So I take off the airbox and air flow meter as per picture in your book?

Cheers,

Mark.

Adrian

Dear Mark,
You do not need to take anything off to access the throttle cable and throttle quadrant. It is right in front of you to the left of the ISV. The quadrant is the bit with the microswitches on it and the bit that moves when the cable moves.
Ciao,
Adrian
964C4

Mark Brook

Adrian,
Thanks for that. I won't get a chance to work on her until tonight, I'll let you know how it goes !!!

Cheers

Mark.

Adrian

Dear Mark,
No problem. Please be advised that I am off to Le Mans on Monday 7th June and will not be back until the evening of the 14th June.
So if I am not posting to your questions during this time, I am not ignoring you, I am out of house.
Ciao,
Adrian
964C4