Seat 1.2 BXV cutting out when warm

[Aaron75]

I have a 57 plate 1.2 BXV that's only done 39k genuine miles, its been cutting out displaying flickering warning lights on dash as its cutting out.

Initially the mechanic diagnosed from the fault codes indicating both crank and cam sensors intermittent and implausible signals and various other codes that the timing chain must have slipped a couple of teeth, the chain had slipped two teeth and he replaced the timing chain kit.
However the car would not start properly and when it did it would run for a bit and become rough idle and then cut out. He played with the ECU sprayed contact cleaner sealed dried it and the car was fine for two weeks.
After a fortnight it did it again and I put it on VCDS which displayed
Cam
Crank
Throttle position sensor
ECU management implausible
I sent ECU off to ECU testing they returned it checked sealed stating no issues.
I replaced it back into car it started fine ran around the block till it warned up and then it started to cut out lights flickering on dash.
I have noticed the temp gauge not working (but no code referring to it on VAGCOM
I let it cool down and tried again warming up it was fine, I monitored the temp of engine using OBD11 button live testing on VAGCOM and it reached 42 degrees and I noticed the light on the OBD cable flashing ref/green telling be the communication with ECU was being affected and lo and behold the warmer the car got it started cutting out and the readings stopped.

The same codes all re appear after clearing them letting car cool down and it runs fine until it warms up and lose throttle and the engine misfires and cuts out.

Any ideas anyone ???

 

[RUM4MO]

It could be one of these situations where the ECU is becoming faulty when it has been powered up for a certain period of time, probably not something that the ECU test house would look for - unless you pointed out what you have discovered. All their testing for faults would probably only take 5 minutes or less - that is a guess only.

You could try keeping the ECU cool using a freezer spray or two, but that might just end up with some of the ECU components getting over stressed and damaged.