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Chasing an issue, at a loss after trying many things…Update

The Baron3

Monza
Joined
1 Nov 2021
Messages
207
Totally at a loss, so am turning to the 911uk masses for help from their combined wisdom.
Car: 1999 C4, none cable.
Symptoms
: car runs fine, however once the car is upto temperature it will occasionally stall when idling when it is hot outside, it will then take 6 or 7 cranks to get car going again, running the AC doesn’t really help. It tends to happen when the petrol is low, with a full tank it doesn’t happen. There is no fault codes, no EML on dash etc.
Things done: at Porsche specialist had the the fuel pump checked for preassue on diagnostic's machine all seems good. which was my and his first thought with his reader, he had found a couple of air leaks and the exhaust manifold was blowing, now both fixed also with cleaning out the TB, new fuel filter.

Other things done previously : New MAF, new camshaft solenoid, new O2 sensors, these where all changed chasing similar fault and following reader fault codes, these codes are gone and symptoms are much better but still getting the engine cutting out when idling but only when fuel is very low.

Any ideas would be much appreciated as I am hoping to go on a road trip to south of france in a week via Switzerland and I do t trust the car at the moment.
 
Has your mechanic checked the fuel pressures send and return by removing the hoses in the engine bay so that you are pumping out fuel.? I had a very similar problem. We were convinced it was the pump, but it turned out to be water in the fuel. Long shot...but easy to check.
 
Unfortunately very difficult to diagnose without going through a lot of stuff which you already have but if low fuel is the key to it stalling then that discounts many things and would lead to a lack of fuel/fuel pressure in that scenario.
I would remove the pump from the tank and have a really good look at the hoses for a possible crack or split , they do age and lose their suppleness.
Also all the plastic parts around the pump , look really carefully with your glasses on (if you need them)
I feel your pain especially if you're planning a big trip in it, btw , have you got Euro cover on your Insurance , I've just done it on my Insurance as we're heading to Sweden via Holland, Germany and Denmark in the Turbo next week..can't wait.
Good luck with the issue, I genuinely hope you find it.
 
When it does it, try removing your fuel cap and see if that cures it.
 
Definitely check the filler cap, or more specifically its seal.

There are also 2 valves that keep pressure in the tank, and one which regulates vapour - one is located near the filler the other in the engine bay. Failure of any of these will make warm starting difficult.
 
Might be worth watching 9Werks Youtube video today , he has a similar issue but not the same, something to do with the Evap system and carbon canister . Interesting watch regardless.
 
Might be worth watching 9Werks Youtube video today , he has a similar issue but not the same, something to do with the Evap system and carbon canister . Interesting watch regardless.
Funnily enough I watched that this morning, I subscribe to his YouTube channel.
 
I had something very similar on a non Porsche, car would run fine and then die for no reason at random times. Turned out to be a bad crank sensor (there were no fault codes displayed). Once this was changed (as it was a cheap part) the car ran perfectly.
 
Start with all the known "warm start" issues and solutions - none of those are expensive and typically relate to things like dry o rings/seals and worn out EVAP related valves that are pretty accessible and easy to deal with, some with as little as a wipe of vaseline...
 
Not used the car since it cut out, as waiting for my Porsche guy to get back from holiday, out of interest I plugged my Icarsoft reader in and have 3 fault codes:
P1115 oxygen sensor heater ahead of cat1 bank 1
P1128 Oxygen sensing adaptation idle range bank 1
P1130 oxygen sensing adaptation idle range bank 2

Anymore ideas from above?
 
I second the crank sensor for checking. It's common on many cars that that a failing crank sensor causes engine cut-out when it gets hot.
No idea of the price or difficulty in replacing it, but its going to be on the outside of the engine so could well be a diy job?
 
The issue happens more when the fuel level is low. Can't see how that can be anything to do with the crank sensor.
 
The issue happens more when the fuel level is low. Can't see how that can be anything to do with the crank sensor.
That is true, but working in customer service I'm used to conflation where one event seems to get tied to another.
If it absolutely never happens unless the tank is near empty then that's the best clue. But 'tends to happen' isn't never.
Testing a crank sensor should be easy so worth a go.
 
I’ve had the crank sensor checked when I had the camshaft solenoid replaced, which is a drop the engine job. I’ve also changed out the evap canister myself a few years back
Car was in my indie for a few days checking everything a few weeks back and found a few air leaks along with a slightly blowing manifold, that has all been done, and we both thought this was the fault. He’s checked all the pressures on the fuel side etc
It’s like Lee Selbys Little Irish been chasing this for a while, just don’t seem to be able to pin it down.
I don’t think I can use the car going to france next week, I will have to take my old 1997 Boxster with 220k miles on the clock, had that from new and it has never let me down. I just don’t trust the 996
 

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