Engine starts but stalls after startng

Talk and Tech about turbocharged 924/944/968 cars
Efren
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Managed to get the sensors in and seems to be working.

This is the main issue I needed to troubleshoot but couldn’t begin till the sensors are replaced.

Anyone have an idea.it was running fine on the freeway then all of sudden it just stalled and died. Manage to get it started but it keeps stalling and dying

Hmm. Can’t add video.

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Last edited by Efren on Mon Nov 03, 2025 5:42 pm, edited 1 time in total.

#1

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Tom
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For videos, the best way is to upload to Youtube and post the link here -- it will embed and play within the thread. You can set it to unlisted if you don't want it indexed on Youtube.


When these cars start and then immediately die, it's often a problem with the air-fuel ratio. That, in turn, is often a big vacuum leak, like an intercooler coupler blown loose. I'd give it a good visual inspection to see if any of the big intake couplers have blown lose. If not, then I'd check the air-flow meter and it's signal to the DME, and fuel pressure (quick check before full pressure check -- look for fuel in the vacuum line to the FPR). Then go back to basics checking fuel and spark and going from there.

#2

Efren
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Tom wrote: Mon Nov 03, 2025 5:30 pm For videos, the best way is to upload to Youtube and post the link here -- it will embed and play within the thread. You can set it to unlisted if you don't want it indexed on Youtube.


When these cars start and then immediately die, it's often a problem with the air-fuel ratio. That, in turn, is often a big vacuum leak, like an intercooler coupler blown loose. I'd give it a good visual inspection to see if any of the big intake couplers have blown lose. If not, then I'd check the air-flow meter and it's signal to the DME, and fuel pressure (quick check before full pressure check -- look for fuel in the vacuum line to the FPR). Then go back to basics checking fuel and spark and going from there.
Yes. I’ll be taking everything off to see what I can find. Thank you Tom.

#3

Efren
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Purchased a smoke tester and found two leaks which was easy to fix. It dies start and after several seconds it starts to stumble and almost cut off but catches back and idle ties to normal but cycles back to stumbling.

I disconnected the TPS and start the engine. It idles fine with no stumble or jerking or sound like it’s going to shut off. It’s actually smooth with TPS disconnected but it will stumble if I try to blip the throttle but I think this is normal since TPS is disconnected.

If I plug it back in the issue comes back.

TPS issue? I had a spare but can’t find it.

Is there a way to test? Nothing on YOUTUBE

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BennSport
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Clark’s has a good page regarding testing the TPS that I used not too long ago. https://www.clarks-garage.com/shop-manual/ign-03.htm
Also be sure that you have the right TPS for your car, the PO installed a BMW unit for mine that was completely faulty.
‘83 Platinum N/A 944

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Efren
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Poorsche44 wrote: Thu Nov 06, 2025 1:02 pm Clark’s has a good page regarding testing the TPS that I used not too long ago. https://www.clarks-garage.com/shop-manual/ign-03.htm
Also be sure that you have the right TPS for your car, the PO installed a BMW unit for mine that was completely faulty.
Thanks.
I found one from Toms documents

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Tom
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Right, for future reference, here is our test guide.

viewtopic.php?t=525#p5222

We have them for most of the engine management components. I probably should do a table of contents more like clark's...

#7

t36
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It would be awesome if someone had some spare internal parts for these TPS's.
My old one's internal microswitch failed. I would get hesitation and it would buck when off throttle.
New TPS's are $$$$

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Tom
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t36 wrote: Thu Nov 06, 2025 2:20 pm It would be awesome if someone had some spare internal parts for these TPS's.
My old one's internal microswitch failed. I would get hesitation and it would buck when off throttle.
New TPS's are $$$$
They contain a couple of dollars worth of parts. It's been on my list for years to recreate a cheaper version....

#9

Efren
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Tom wrote: Thu Nov 06, 2025 6:17 pm
t36 wrote: Thu Nov 06, 2025 2:20 pm It would be awesome if someone had some spare internal parts for these TPS's.
My old one's internal microswitch failed. I would get hesitation and it would buck when off throttle.
New TPS's are $$$$
They contain a couple of dollars worth of parts. It's been on my list for years to recreate a cheaper version....
Please please do

#10

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