Hot Stalling

Hey All,

Weird situation.....car starts strong/quickly. Drives fine. Good Throttle response. After about 25 minutes it will stall when stopping or pulling the clutch. It will start up fine but quickly stall unless throttle is applied. Once underway it drives fine but will stall at next stop. The timing is reproducible as I drive it to work. After it cools off for 30 minutes, its fine.

85 308 qv US. I feel it is a heat issue. I had issues with throttle position switch which were similar but started much earlier like after 5 min. Replaced the TPS and it resolved. Still it behaves like the TPS issue previously. Could the switch heat up and fail?

Your thoughts are appreciated.

Thanks,
Charlie

 

Early on in my Euro QV ownership, I had a slight vacuum leak that only manifested itself when the car had been running awhile. Turned out to be a hairline crack in one of the tiny hoses that connects near the throttle body.

 

Lots can be affected by heat (both electrical and fuel issues). Process of elimination, start with the easy stuff first, then get more involved, I.e. change fuel, plugs, plug wires, coils, check running temps..

 

This is an injection engine ? Run the fuel tank down and put some injector cleaner in the tank. The engine on my 87 mondial used to cut out at odd times and this was the fix once a year. No use adding to a lot of fuel so run it well down

 

How long has this been happening?

 

Been chasing the exact same thing for over a year on my 85 QV. Only on mine it's more intermittent. I can drive the car for hundreds of miles without it happening...and then it will do the stall thing 5 times in a 15 minute drive on another day. Like the OP, it always starts right back up and drives fine. Here's what I've changed:

All 3 crank sensors
Warm up regulator
Fuel injectors
Plugs
Ignition wires
All relays and fuses
Distributor caps and rotors
Brake booster check valve
Added additional ground strap to digiplexes

Most of this stuff is good maintenance anyway, and it's been a bit since it's happened. But I've been here before. I won't declare the issue resolved until I've gone at least a month without it happening.

Car recently came back from a major service at Wide World. They couldn't replicate the problem. It hasn't happened since I got it back. They thought it could be related to a vaccum loss on the brake booster...but the booster holds vaccum. And it's a costly repair which I'm not doing unless it's that's proven to be the cause. They were also considering the fuel accumlator, but the stall always happens after the car has been running well at high rpms...so starvation doesn't seem to be a cause. If anyone else has an idea...I'd love to hear it as well!

 

Update. The wiring insulation at the TPS plug was frayed and partially missing. I simply wrapped the exposed harness with electrical tape a few times and the problem resolved! I think it just needed a little extra insulation from the engine heat.

 

There is that - wiring continuity is one thing. Sometimes it’s the fuel pump fuse that is a component issue of a more complex multifaceted problem. No one ever believes it’s a simile fix.
Remember a headache is sometimes a headache - they’re not all tumors.