The car is a 2013 TT RS Plus S-Tronic, 22,000 miles, FSH, spark plugs changed in March 2019, always run on Tesco Momentum 99 RON, no VCDS fault codes.
In another post I was asking for help on an occasional performance loss issue. After numerous data logging sessions I found it to be due to timing corrections. And after more data logging sessions I assumed it was due to high IATs because of the worthless stock intercooler. So I replaced the intercooler with an Airtec. High IAT problem solved and most of the timing corrections gone.
I’ve recently fitted a Ramair Jetstream induction kit and a CRTD4 boost controller (roughly 2.5 psi extra boost). And the timing corrections are back. They're intermittent, in random cylinders and are mostly no higher than -3 degrees. There is an occasional random -6 degree. These might be due to the way the CRTD4 manipulates the MAP sensor, so the ECU sees a leaner oxygen sensor reading than it was expecting, causing it to use the STFT to get the AFR back to where it should be. So it’s effectively always playing catchup and I wonder if it also pulls a bit of timing just to err on the side of caution until the AFR is as expected.
I was curious if the knock sensor readings in VCDS would tell me if the ECU was just being cautious or if it was reacting to knock. Here’s a graph showing a few WOT pulls, mainly in third gear:-
![Image]()
This made no sense to me. If this graph was indeed showing knock, why was the ECU reacting by only pulling -3 degrees of timing? And was it just a coincidence that the knock plot lines had the exact same shape as the RPM plot line? But if it wasn’t showing knock was it really just showing engine noise? I wondered what the graph would look like with the CRTD4 removed. So I removed it and did some more data logging. Here’s the graph, again WOT pulls mainly in third gear:-
![Image]()
Spot the difference. So either my engine is knocking the same on stock boost as it is with an extra 2.5 psi, or this is simply engine noise. And the timing corrections are down to the boost controller, so either live them or get a remap...
And help would be greatly appreciated.
J
In another post I was asking for help on an occasional performance loss issue. After numerous data logging sessions I found it to be due to timing corrections. And after more data logging sessions I assumed it was due to high IATs because of the worthless stock intercooler. So I replaced the intercooler with an Airtec. High IAT problem solved and most of the timing corrections gone.
I’ve recently fitted a Ramair Jetstream induction kit and a CRTD4 boost controller (roughly 2.5 psi extra boost). And the timing corrections are back. They're intermittent, in random cylinders and are mostly no higher than -3 degrees. There is an occasional random -6 degree. These might be due to the way the CRTD4 manipulates the MAP sensor, so the ECU sees a leaner oxygen sensor reading than it was expecting, causing it to use the STFT to get the AFR back to where it should be. So it’s effectively always playing catchup and I wonder if it also pulls a bit of timing just to err on the side of caution until the AFR is as expected.
I was curious if the knock sensor readings in VCDS would tell me if the ECU was just being cautious or if it was reacting to knock. Here’s a graph showing a few WOT pulls, mainly in third gear:-
This made no sense to me. If this graph was indeed showing knock, why was the ECU reacting by only pulling -3 degrees of timing? And was it just a coincidence that the knock plot lines had the exact same shape as the RPM plot line? But if it wasn’t showing knock was it really just showing engine noise? I wondered what the graph would look like with the CRTD4 removed. So I removed it and did some more data logging. Here’s the graph, again WOT pulls mainly in third gear:-
Spot the difference. So either my engine is knocking the same on stock boost as it is with an extra 2.5 psi, or this is simply engine noise. And the timing corrections are down to the boost controller, so either live them or get a remap...
And help would be greatly appreciated.
J
