Apr stage 3 is38 problems

[aceswld]

Hello all!
This is my first post because ive had this car about a month. I bought it built
Its a 2017 1.8 is38 stage 3 auto.
I have now come across 2 problems.
1) i have had 3-4 incidents of overrevving between shifts causing the est light to pop and loosing power. Its like getting stuck between gears. Its a non dsg but i get a lot of dsg farts normally but when this happens it just farts for like 2 seconds and then boom est light. Every time i pull over turn the car off and back on and its back to normal.
2) I believe i have compressor surge on throttle. I have an forge v2 bov. Sometimes when i step on it a little i hear the turbo flutter while accelerating. This is my first turbo vehicle so its just kinda an assumption that the flutter on acceleration isnt normal. And on top of all that the vehicle is slower than it is when i first bought it but not by much, I suspect a boost leak. Any tips/info would be wonderful i have some friends who say it might be a bad turbo bearing but i really dont want to get a new turbo im happy with the is38. Please help a fellow 1.8er!

 

[ZuMBLe]

Compressor surge is when the turbo is building boost and you let off the throttle and the air backs up in to the turbo. I doubt this is happening on at part throttle. What you could be hearing is normal wastegate sounds. Do you have any other mods besides the tune and turbo? Did you install it all yourself?

If you suspect a boost leak, you should check all positive pressure connections from the turbo to the throttle body.

 

[MeltedSolid]

Compresser surge at part or full throttle was a lot more common on the mk6 platform, but it could also happen on the mk7. It's not great for the turbo, but if it doesn't sound severe it's probably not a problem, but I wouldn't be able to tell you without hearing it. The general consensus for BOV/diverter valve on the mk7 is that the stock one is the best setup for pretty much any application, but I'm not sure if that's related. You might want to try swapping back to stock if you can to see if that helps.

 

[Scanner]

I would remove the forge BOV and place the stock diverter valve back, a new one. Followed by a transmission fluid replacement to be on the safe side also.
I would also check the voltage readings of your wastegate, within range?

 

[tigeo]

Folks always think they have boost leaks when these noises happen - if you have a boost leak, it should be v. obvious as a noise that sounds like air escaping and you won't have the full boost the ECU requires. It's unlikely. The surge you are getting is v. common with the APR tune, do some searching here/FB/etc. and you'll find lots of APR owners with our cars talking about it - I wouldn't worry about it TBH. The BOV is unnecessary vs. the OE DV but I don't think it's causing any drama. Your auto shifting issue - no clue. The auto has been known to have some goofiness vs. the standard/DSG on this platform when tuned and causing EPC/limp mode between shifts.

 

[aceswld]

Compressor surge is when the turbo is building boost and you let off the throttle and the air backs up in to the turbo. I doubt this is happening on at part throttle. What you could be hearing is normal wastegate sounds. Do you have any other mods besides the tune and turbo? Did you install it all yourself?

If you suspect a boost leak, you should check all positive pressure connections from the turbo to the throttle body.

It has an aftermarket intercooler, BOV, turbo inlet pipe, and loads of other stage 3 mods.

 

[jimlloyd40]

It has an aftermarket intercooler, BOV, turbo inlet pipe, and loads of other stage 3 mods.

Try putting the stock diverter valve (BOV) back in. It's the best one anyway.

 

[AceHammer]

Check the spring in the forge BOV, it's probably lost tension or the wrong spring for the IS38. Most likely it has the yellow spring, which comes stock in them. IS38 will 100% stress the yellow and start to cause boost leaks. The ECU also does not play terribly well with aftermarket DVs on shifts, at least with a DSG.

Had the same issues with my Forge eventually just went back to a regular DV.

My spring would lose tension and cause a small boost leak at WOT. Sounded like a mix of turbo failure and surge. I only lost like a pound of boost but it 100% made a difference. After reading how EQT and all the other major tuners recommend stock I switched back.

 

[tigeo]

The comments above - yeah, will be an easy thing but I've heard of the APR tunes getting some surge even with the stocker.

 

[Joe_Mama]

Stop running a BOV. VWs run on a closed loop. The ECU expects air to be diverted and put back into the system, not vented to atmosphere. This isnt a Subaru. Put the DV back on.

 

[tigeo]

Stop running a BOV. VWs run on a closed loop. The ECU expects air to be diverted and put back into the system, not vented to atmosphere. This isnt a Subaru. Put the DV back on.

That is 100% not accruate - there is no MAF on the MK7 that is "looking for that air". A bazillion folks run aftermarket BOVs on these cars with no drama. With that said, I don't disagree - no reason to run a BOV, the stock DV is more than up to the task. If you want some noise, run an open intake.

 

[Joe_Mama]

A bazillion folks run aftermarket BOVs on these cars with no drama.

That's funny... everyone i see run a BOV on these cars has problems, including the OP. But whatever you say

 

[tigeo]

That's funny... everyone i see run a BOV on these cars has problems, including the OP. But whatever you say

I know plenty of folks on this platform running BOVs that have no problem. Also, do we even know what he is desribing is out of the ordinary? Surge/noise is always something folks posts about and I've seen plenty of folks with the stock DV asking "what is this noise". Likely normal tuned turbo stuff. Again - there is no MAF so how exactly is the ECU having issue with the charge air being vented in front of the compressor or not? In the older MK6 etc. this was an issue as those had a MAF and could have AFR issues between shifts if you ran an atm BOV.

 

[ZuMBLe]

That's funny... everyone i see run a BOV on these cars has problems, including the OP. But whatever you say

Its true. The MK7s don't have an air flow meter at the intake that it's using calculate fuel. The car uses pressure and temp sensors way down the line to measure air density. When the BOV vents air, the throttle should be closing, shouldn't matter.

 

[Joe_Mama]

I know plenty of folks on this platform running BOVs that have no problem. Also, do we even know what he is desribing is out of the ordinary? Surge/noise is always something folks posts about and I've seen plenty of folks with the stock DV asking "what is this noise". Likely normal tuned turbo stuff. Again - there is no MAF so how exactly is the ECU having issue with the charge air being vented in front of the compressor or not? In the older MK6 etc. this was an issue as those had a MAF and could have AFR issues between shifts if you ran an atm BOV.

Maybe you are right. I am more used to the mk6 platform