Golf R 7.5 SE is losing torque randomly during pulls

[cyn]

Hi all!

I've been driving a Golf R 7.5 Special Edition for the past few months and recently tuned it with Galano Stage 1 ECU and Stage 3 TVS TCU (I switched from Galano TCU only as I preferred TVS from my previous Golf). The car is completely stock otherwise.

Since tuning, I’ve been encountering a strange issue: during a pull, it starts off strong, but about 1 out of 3 times, I randomly lose torque. If I back off the accelerator and press it again, the car responds normally. There are no logged faults in any modules, and no warning lights on the dash.

I've been trying to troubleshoot this with my mechanic, but it's tricky since it’s not consistent. This weekend, I did some datalogs with the OBDEleven app (which can be a bit of a hassle), and finally captured the issue.

In the datalog, you can see a few normal pulls, but on the last one, the torque drops by almost half (confirmed by the butt dyno).

datazap.me | cynate | Golf R 7.5 Stg1 Torque Loss


Any ideas?

[Lucas_R]

Have you turned off traction control to rule out that its not simply trying to wheelspin and the traction control is kicking in? Also, what gear are you doing these logs in? If im reading your chart correctly, the torque drop is happening at about 4000rpm which is when the Golf R is really starting to pull hard - especially with a tune.

Another scenario is that you are hitting a torque limiter in the TCU software. Im not sure what TVS do in relation to the torque limiters in their software, but when you are running different software for the ECU and TCU then its possible that the Galano ECU tune is pushing more torque than what the TVS TCU tune is allowing......or something isn't quite meshing correctly due to 2x different software brands. I would advise not mixing brands when it comes to ECU and TCU tuning.

[cyn]

Have you turned off traction control to rule out that its not simply trying to wheelspin and the traction control is kicking in? Also, what gear are you doing these logs in? If im reading your chart correctly, the torque drop is happening at about 4000rpm which is when the Golf R is really starting to pull hard - especially with a tune.

Another scenario is that you are hitting a torque limiter in the TCU software. Im not sure what TVS do in relation to the torque limiters in their software, but when you are running different software for the ECU and TCU then its possible that the Galano ECU tune is pushing more torque than what the TVS TCU tune is allowing......or something isn't quite meshing correctly due to 2x different software brands. I would advise not mixing brands when it comes to ECU and TCU tuning.

Unfortunately it's not the traction control as it occurs with it both on, in sport, and completely off. Also in my previous GTI the TC light would flash whenever its kicking in, which isn't happening on the R. The torque loss happens in any gear but a lot more reproducible/noticeable in 4th.

And yeah the TCU pulling torque was my initial thought as well, since I had a similar issue on my Polo where the ECU was tuned but TCU wasn't and the torque would limit quite a lot. Initially my R was tuned with both Galano Stg1 ECU+TCU, but I prefer the shifting logic of TVS so I switched. The torque loss is happening on both TCU tunes sadly.

Do you think it could be wastegate related? I can see in the datalog that my actual boost drops quite a lot during the last pull, and I've just been informed by VW that my wastegate has play and they are recommending to replace the turbo for 7k

[Lucas_R]

I dont think it would be wastegate related - but could be wrong. I guess its possible that its overboosting and hitting a boost cut that is programmed into the ECU software. Save yourself $6k and just get a new wastegate actuator if yours has play in it. $7k to replace the turbo is an insane amount of money - you could replace the turbo and get stage 2 parts for $7k.

06K145725T - IS38 Electronic Waste Gate Actuator - Audi 8V S3 & VW Golf MK7R– VAGPARTS Australia

It definitely looks ECU/TCU related as it drops off suddenly and significantly. Its certainly hitting a limiter at 450ish nm of torque and just falling off a cliff.

I would not be taking a modified car (or even a stock car) to VW for this kind of diagnosis, looks like you are in Sydney and there are dozens of independent VW specialist mechanic shops down there. Might be a good idea to start with the workshop that did the ECU tune and get them to do some logs and discuss with Galano - or possibly reach out to Galano yourself with your logs and feedback to see what they say.

[petemac110]

Why not contact Galano directly - there's only so much speculative info that can be gathered from a forum on such a technical matter.

Chris @ Galano could get to the bottom of this pretty quickly.

I highly doubt it is a wastegate issue - the tuning of the EA888 is based around "requested torque" levels, not target boost levels. If you're seeing a drop in boost, it is because the ECU is limiting the requested torque for some reason or another.

[cyn]

I dont think it would be wastegate related - but could be wrong. I guess its possible that its overboosting and hitting a boost cut that is programmed into the ECU software. Save yourself $6k and just get a new wastegate actuator if yours has play in it. $7k to replace the turbo is an insane amount of money - you could replace the turbo and get stage 2 parts for $7k.

06K145725T - IS38 Electronic Waste Gate Actuator - Audi 8V S3 & VW Golf MK7R– VAGPARTS Australia

It definitely looks ECU/TCU related as it drops off suddenly and significantly. Its certainly hitting a limiter at 450ish nm of torque and just falling off a cliff.

I would not be taking a modified car (or even a stock car) to VW for this kind of diagnosis, looks like you are in Sydney and there are dozens of independent VW specialist mechanic shops down there. Might be a good idea to start with the workshop that did the ECU tune and get them to do some logs and discuss with Galano - or possibly reach out to Galano yourself with your logs and feedback to see what they say.

Unfortunately Chris from Galano seems to be away for the time being - I've sent the data logs to my tuner who has sent them to Chris, but I have this three month dealer warranty (as I bought the car used) that expires in two weeks and not sure when I'll hear back. Hence if there's anything mechanically wrong with the car that could be causing this and it's not just a simple fix in software, I could save a lot of money fixing it now

[Sharkie]

Unfortunately Chris from Galano seems to be away for the time being - I've sent the data logs to my tuner who has sent them to Chris, but I have this three month dealer warranty (as I bought the car used) that expires in two weeks and not sure when I'll hear back. Hence if there's anything mechanically wrong with the car that could be causing this and it's not just a simple fix in software, I could save a lot of money fixing it now

If you tuned the R after you bought it, your warranty (used or new) would be void. If it was me, I would have the current ECU tune removed and go for a safer (milder) ECU tune from another reputable tuner. Galano is on the extreme side of tuning, and a milder tune will likely be safer and work without issues (subject to no inherent hardware issues).

[cyn]

For anyone following along, worked out with my mechanic (not VW) that the wastegate indeed has failed and is causing me to loose boost. New turbo is on the way..

[Lacksballs]

Seems a bit extreme that a new turbo is required just for a replacement wastegate?

[Lucas_R]

For anyone following along, worked out with my mechanic (not VW) that the wastegate indeed has failed and is causing me to loose boost. New turbo is on the way..

If you refer to my link posted previously, you can buy a replacement wastegate for just under $700 vs multiple thousands for a new turbo. Unless you have warranty covering this repair then it would be wise to only replace the failed item.