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Possible ECU failure

Peter Thorne

New member
Hi guys,

I´m new to this forum and wondering if someone has experienced a similar problem. I own a 2011 Golf R (European version) with the following mods.

Cold air intake
3" down pipe
Milltek non resonated and decat exhaust system
165 bar FPV
Autotech HPFP internals
Torqbyte PM4 FPM
Racingline IC
Racingline Oill catch tank system
HG Motorsport throttle pipe

The car has a custom software from a known Swedish tuner.
But it is equivalent with a stage 2+ software.
The problem started a couple of months ago, when I lost all power from the engine, just like snapping your fingers. I knew that my Turbo was on it´s way, because it was smoking quite badly when started from cold. So I obviously thought that it was shoot. It also threw a P0299 code which did me even more certain. I took the down pipe off and checked the play, and sure enough the shaft was mowing quite badly. A month ago a new TTE420 was purchased and installed. Of course it was fitted with new seals and gaskets. I also installed a new BAR-TEK perfomance LPFP, a Torqbyte PM4 FPM a 165 bar FPV and new spark plugs as well. Everything was then double checked for leaks before start up. Everything looked and sounded great.
The engine was running for 15 min. then checked for leaks etc. again.
I also checked for fault codes in VCDS but there was no codes what so ever.
Great, the car is ready for a cautious test drive. I drove the car for another 15 min then checked everything again a third time.
Then I pushed the car a bit harder and immediately noticed that the engine was performing just as bad as before.
Ok, checked everything again, including fault codes but there was none.

When logging the car (the best I could) you can tell that the throttle plate angle will only open at 34%, even if you push the pedal to the floor. However when looking at the values with ignition on only, everything seems ok and the values add up as specified. But as soon as the engine is loaded the same thing happens. It will not go beyond 34%.

The system is pressure tested without any leaks.
Nothing really happens when pulling the MAF and MAP sensor.
The DV is checked twice.
Fuel pressure is good (both HP and LP)
No retardation on timing.
Requested boost pressure is lower than actual.
Engine load is poor.
Engine idles and starts ok.
Engine revs above 3500rpm, so it should not be in limp.
No fault codes what so ever.

I even flashed the ECU with the original software.
The engine is exactly the same. It will not even throw a fault code for the de cat or down pipe.

What the hell is going on??
Could it be a faulty ECU? (not calculating or stuck in a certain mode)
Any help would be much appreciated.

Logs can be sent if any interest (they were a bit too big to attach)


Peter Thorne

New member
have you gone back to the tuner to ask them to pull logs?
Yes, I have heaps of logs. I have a great dialogue with my tuner. He is as puzzled as me.
It's like it's in limp mode, but still not if that makes any sense.

Most of the requested values are lower than the actual values so it's definitely not a boost problem.
As mentioned before, it's like the ECU can't calculate the values. An VCDS auto scan doesn't give you any clues either unfortunately.


Peter Thorne

New member

So, thought we found the mystery when we opened the ECU. One of the circuits looked a bit melted, so my tuner got me a used ECU which he cloned.
Unfortunately, the replaced ECU didn´t fix the problem when tested in car yesterday :-(
I also tested to change the MAP and MAF sensors, just to be sure.

The ECU will still not give more than 32% throttle plate angle under load. All values are within specs when testing/log with VCDC and ignition on only.

Could a throttle body be faulty without any fault codes? Could it be some strange mechanical failure with it that doesn´t throw a code?

I´m getting pretty desperate, so any help/thoughts would be much appreciated.