E53 4.4 keeps cutting out when coming to a standstill

[bcredliner]

Originally Posted by upallnight

Before throwing parts at it did you try to read some live data? Do you know how many G/S is flowing through the MAF? Sounds like the idle may be too low when it comes to a stop. Could be a vacuum leak, since when the throttle plate is closed, the vacuum is the greatest.

When engine is cold it is in open loop. When cold engine is first started the auxiliary air pump is also running. Since it is stalling you may be able to hear a vacuum leak. If not, you can try spraying carb cleaner around vacuum hoses, the intake, etc. If there is a significant vacuum leak the engine will increase RPMs when carb cleaner is sprayed on it. You can also use starter fluid or a propane torch.

[zu11y]

I will double check the vacumn system but just to clarify it does not stall when cold only when warm

[bcredliner]

Originally Posted by zu11y

I will double check the vacumn system but just to clarify it does not stall when cold only when warm

I understood it doesn't stall when cold. In open loop and with aux pump running it likely would not. That was my point. Sorry I wasn't clear.

[zu11y]

Ah got ya bud sorry for the misunderstanding. Ive finally got a week off work so will go over all the vacumn lines

[zu11y]

Just a quick update. Spraying the vac pipes did not cause any higher rpm but it did prevent it from cutting out. When slowing down the x sounds like its about to cut out but wil revive itself, this happened with the carb cleaner all over the vac pipes

[upallnight]

Did you spray the CCV at the rear of the engine?

[bcredliner]

Carb cleaner can cause either a increase or decrease in idle. If I understand correctly the idle decreased. Suggest spraying in as small an area as possible with spurts to pinpoint the leak.

[zu11y]

Hi sorry for the misunderstanding. The cleaner did not make a difference when sprayed, but when i test drove it, it did nlt cut out were it would usually do but instead came very close to cutting out then went back to normal on its own

[bcredliner]

Spraying does not always find a vacuum leak but is always worth a shot. Be sure you have sprayed CCV as suggested. If so, a conclusive troubleshooting method is a smoke test but since the cause could be something else I would continue to troubleshoot. Is hard acceleration normal? This video might help. Covers most of what could be causing your symptoms. https://www.youtube.com/watch?v=ePXODqkfIvI