E53 4.4 keeps cutting out when coming to a standstill
 

As title guys,

My e53 4.4i keeps cutting out when i am coming to a stop
It does not do it when the car is cold just when upto temp.

I have scanned the car and found three faults which are as follows:
98- Tank venting valve
140 - electronic thermostat control
115- hot film air mass sensor


Based on the above can anyone point out which of the faults are causing the car to cut out.

Any help is appreciated

Unplug your MAF while running and see if it runs better or dies.

Hi
Cheers for the reply, i have unplugged the maf and there is no change whatsoever. I took a look at the live data and there is no reading for the maf plugged or unplugged.

Furthermore i have realised that during its cold phase the car is idleing and around 750rpm

But when the cutting out begins the idle speed is around 500rpm.

Fuel filter?

Good day!!

For the easy checks, make sure you have your fuel cap in place... If you have the means to swap with another, I'd do that... That might get rid of your tank venting valve fault...

I agree with 740iS about the MAFS... Sometimes you can get an indication of them going bad if you tap on the top while the vehicle is running... If the engine idles differently during that abrupt thump, it is going bad... However, not getting readings while plugged in kinda says it might be the cause... I forgot to plug mine back in once a while back and I got the same symptoms... Mine never really died, but it really wanted to a few times... You have a good used one you can swap it out with to verify?

Good luck!!

Cheers!!

The MAF would have to be suspect. When you disconnect it? It should revert the engine to a default MAP. So you should notice a difference in engine running/revs/speed/idle etc.

If you do not notice any difference? It is "possible/probable" that the MAF had died and your engine is permanently now running on the defaulted MAP. To test this you, will need to put in a new or known good MAF.

Agreed, this is what I was pointing to also. If the MAF is dying you'd notice a change when it went to default. If no change at all, it seems you are already in default as the system doesn't see the MAF. Your scan also seems to point there too.

Most don't realize that the MAF is a consumable part and they do wear out and need periodic replacement. Just like the O2 sensors, they last between 75k and 100k miles on average.

Thanks for all the input guys. I have ordered a new maf and will report back

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.

Sorry for the late reply guys. This problem is still ongoing. I have replaced the maf with a new genuine one and now the error code has gone and live data is with in range but it is still cutting out.

The other error for the thermostat is still there but cant imagine that causing the car to cut out.

Any ideas guys