Boost cut?

[Joe98]

Hi all, new here so apologise if this is in the wrong place but I am seeking help I am experiencing major issues with my mk7 golf r.

I experience what I believe is a boost cut or maybe even a fuel cut?

Current setup is stage 2 ECU map and gearbox map by Infinit Performance (between 400-420bhp) Airtec induction kit with turbo elbow, 3” scorpion downpipe res delete standard back box.

I have just changed the following in an attempt to find the issue, new plugs gapped to 0.28, new coil packs, new diverter valve, haldex serviced and gauze cleaned, engine oil and filter change.

Now I know everyone will say it’s the tune well I’ve been advised this map has been fine on over 100 golf R’s we have done a data log and all looks fine... the issue only happens once the car is warm and if I turn the car off for 20 mins then drive again the issue is gone but returns pretty quickly. I’m just lost and any help is appreciated!

Here is a video of my issue and please bare in mind that my foot is planted and at no point until the end do I let off, I’ve scanned the car multiple times I have NO error codes whatsoever!

Thanks, Joe

 

[Joe98]

Also please note that before I made all the changes to my car it was stage 1 and I never had any issues like this...

 

[Reggie Enchilada]

You can hear the DV opening in the clip. Pull it and check its condition, look for obvious damage. May just be a bad solenoid. Replacements aren't expensive. Unrelated to this issue, but you need to have an intercooler upgrade when tuned more aggressively than stock power levels.

 

[Joe98]

You can hear the DV opening in the clip. Pull it and check its condition, look for obvious damage. May just be a bad solenoid. Replacements aren't expensive. Unrelated to this issue, but you need to have an intercooler upgrade when tuned more aggressively than stock power levels.

Hi Reggie!!
Thank you for getting back to me, I’ve already replaced the Diverter valve for a known working one! Yeah I know I need an intercooler and I am monitoring temperatures and they seem really good at the moment but yes it’s on my list!!

 

[Reggie Enchilada]

Have you checked for any fault codes? Both historic/stored and active ones? Take some data logs if you can, they'll be a huge help in diagnosing this.

 

[Reggie Enchilada]

Also just noticed how low your fuel gauge is. Several people on here have ran into issues with the LPFP getting starved due to the fuel sloshing during hard launches/acceleration when the tank is low. Entirely possible that's the cause.

 

[Joe98]

Have you checked for any fault codes? Both historic/stored and active ones? Take some data logs if you can, they'll be a huge help in diagnosing this.

No fault codes that I can pick up... I once got the light on and error code PO3A5 when map was first done but it disappeared all on its own...

Also just noticed how low your fuel gauge is. Several people on here have ran into issues with the LPFP getting starved due to the fuel sloshing during hard launches/acceleration when the tank is low. Entirely possible that's the cause.

I wish it was this simple but I’m currently on my 3rd full tank trying to diagnose this issue

 

[Joe98]

Another clip, 4th gear pull flutter on acceleration

 

[Reggie Enchilada]

Hmm, I can't find anything on that code, but PX3XX codes are typically related to ignition issues.

That pulsing is definitely the DV. MK7.5 pulse the DV differently to MK7's but based on your post you have a MK7, so you shouldn't have the DV pulsing like that. Have you contacted your tuner for their input? Just spitballing here, but there is a possibility that the tune is pulsing the DV as part of some sort of weird boost management or torque limitation strategy.

 

[Diggs24]

Log and post to datazap.

 

[EpicTech]

Wouldn't the DV be doing that to hold whatever the target boost is set for? Considering if the car is actually overboosting...

 

[Joe98]

Hmm, I can't find anything on that code, but PX3XX codes are typically related to ignition issues.

That pulsing is definitely the DV. MK7.5 pulse the DV differently to MK7's but based on your post you have a MK7, so you shouldn't have the DV pulsing like that. Have you contacted your tuner for their input? Just spitballing here, but there is a possibility that the tune is pulsing the DV as part of some sort of weird boost management or torque limitation strategy.

yeah spoke to tuner and he said won’t be the tune as it’s been used on over 100 different golf r’s so will be an issue with the car especially only happens once the car has warmed up

 

[Joe98]

Wouldn't the DV be doing that to hold whatever the target boost is set for? Considering if the car is actually overboosting...

I’ve changed the DV already :/ what about if I add a another spring to the DV?

 

[iso100]

It's the tune. Your tuner is trying to avoid having to do work.

When the ECU detects that you're breaching boost limit it will close the throttle to compensate. That's why you hear the dump valve.

It's an easy fix in the tune but you are running a generic flash tune. You will need to upgrade to an "e-tune" so the tuner can revise boost strategy after reading your logs.

 

[Joe98]

It's the tune. Your tuner is trying to avoid having to do work.

When the ECU detects that you're breaching boost limit it will close the throttle to compensate. That's why you hear the dump valve.

It's an easy fix in the tune but you are running a generic flash tune. You will need to upgrade to an "e-tune" so the tuner can revise boost strategy after reading your logs.

it’s a completely custom tune already tried adjusting the parameters