Applying brake pedal stalls car? Problem

[Mother]

Applying brake pedal stalls car when cold but restarts with no problem and also seems to go away most of the of the time when it is warmed up. Anyone had this problem.

Edited October 21, 2009 by Mother

[larez2]

Is your battery/alternator indicator glowing? My guess is that perhaps something is wrong with your electrical system like maybe your alternator and or battery or maybe something with your supercharger sucking too much power at startup. Since when you apply your brakes that uses up some juice, maybe enough to stall your car.

[wvicary]

No check engine light or any other odd issues happening?

[slbates]

Applying brake pedal stalls car when cold but restarts with no problem and also seems to go away most of the of the time when it is warmed up. Anyone had this problem.

I had this problem on another car several years ago. It was the power brake booster. Hitting the brakes at idle introduced a big vacuum leak.

[Mother]

Is your battery/alternator indicator glowing? My guess is that perhaps something is wrong with your electrical system like maybe your alternator and or battery or maybe something with your supercharger sucking too much power at start up. Since when you apply your brakes that uses up some juice, maybe enough to stall your car.

Supercharger is off at present and the alternator is new and registers 13-14V and lights work ok not draining anything, it just simply shuts off if I tap the pedal almost like it is the brake switch.

No check engine light or any other odd issues happening?

I do have a check engine light on but due to something else unrelated last time I checked and need to stick the durametric on it again, but can not remember ... is there is anything that would show the symptom I have. I'll give it a try tomorrow. I'll post up some P error codes tomorrow. My ABS abd OSM lights are coming on and off at times fluid is full and have changed the clutch master cylinder recently.

Applying brake pedal stalls car when cold but restarts with no problem and also seems to go away most of the of the time when it is warmed up. Anyone had this problem.

I had this problem on another car several years ago. It was the power brake booster. Hitting the brakes at idle introduced a big vacuum leak.

Interesting I do think I have a problem with the booster the brakes have to be pumped up and have changed most things but that. I also have ABS and PSM coming on/off but has plenty of fluid. It just seems odd almost like it's when the brake switch is energized cold that it stall/shuts off at idle without actually applying pressure yet and when I drove down the block to the first stop sign it did not stall and using actual brake pressure. Edited October 22, 2009 by Mother

[Mother]

I do not have the schematic in front of me but anyone know if any of the brake switch wires could actually shut down the car.?

[RFM]

I would check the booster and the one way valve on the entry of the booster to be sure, as "slbates" suggest. I have a question regard the super charged engine, which i'm not experienced with, if the engine is equipped with a separate vacuum pump (on the camshaft) there should be no problem, pump>booster is a separate circuit. If it is a earlier atmospheric engine, the intake produce the vacuum needed for the booster to work as it should, what have you done to switch the system from vacuum (atmo.) to pressure (charger). Most part of non atmospheric engines use separate vacuum pump, electric/hydraulic booster system, reverse acting booster, etc. Is there nothing wrong with? If not ignore this, as said, i have no experience with chargers on Porsche flat six engines, i try only to help.

[Mother]

Nothing extra is added for running a Supercharger and should have no effect on the brake circuit that I know of or did I miss something in the question. The stock engine vacuum is used as far as I know for the brake booster from what little I know of the brake system.

[Mother]

Using durametric

error codes DME

PO 0410 or 80 porsche code secondary air

PO 0411 or 208 porsche code secondary air

ABS /PSM

PO 4210 right speed sensor

Voltage supply is 13.7V

Cleared codes everything but speed sensor cleared, the others occur from time to time.

Boy that booster looks like a pain in the xxx to change but where is the check valve and if by the picture this is it does it just pull out of it? Also the line goes to something I'm not familiar with anyone venture a guess.

Edited October 22, 2009 by Mother

[RFM]

Pic. 1 shows one way valve (pulls out), Pic. 2 shows connector via intermediate part to line coming from engine compartment.

In fact my question was, what's happen with the vacuum operated systems, brake booster, canister purge, etc. which are build for atmospheric engines hoes create vacuum, and receives with a charger, pressure. Agree that even a charged engine create vacuum on idle, but no longer on load (pressure), can the potential one way valves, build in the systems, hold the pressure without damage? Is there enough vacuum present in the booster to guarantee a reasonable brake assistance while driving, which was the reason why Porsche mounted a separate vacuum pump on the later engines, even the atmospheric ones. I can imagine that the pressure delivered by the "charger" comes very low, with the standard camshafts (profile and timing), injectors, etc. and the lack of a over boost valve, but it's still weird to me.

[Mother]

Thanks for pointing out the check valve. At 1/2 bar or at around 5 psi charge pressure is very little for a check valve to handle and the systems that have been used for years seem to not suffer from the pressure. Most if not all I know of use a BOV valve to release surge pressure when going off WOT to protect the engine. I am not familiar with the brake boost system workings so not sure, however others do not suffer from insufficient brake boost that I am aware of using a supercharger.

Edited October 23, 2009 by Mother

[RFM]

Thanks for the reply and time.

[Mother]

Noticed something unusual last night with the ignition switch, that if I turn the key switch slightly to the right when car is running the car stalls (maybe safety precaution) or if I step on the brake pedal. Also noticed when I turn the key switch to the 1st ON position (car not running) that the idiot lights/warning come ON but when I relax the key the lights go out and seems to not stay in the on position keeping the lights ON. Maybe I have a ignition switch problem? The ignition switch is not but a maybe 2 years old with little use.

Anyone

Edited October 25, 2009 by Mother

[wvicary]

Replace the switch. Cheap and easy to change out as they have a very high failure rate.

[Mother]

Thanks, I agree and will take that route.

[1999Porsche911]

Have you checked what your vacuum does when you apply the brakes and the car stalls?

[Mother]

Have you checked what your vacuum does when you apply the brakes and the car stalls?

I was just going to test the check valve at the booster. No, I have not how is this done.

Edited October 27, 2009 by Mother

[Mother]

Just thought I would let everyone know I changed the ignition switch and problem has not recurred.