Low boost (limp mode) when car is driven more then 30 minutes or when its hot

**TooDamnFresh** · 04-30-2018 09:18 AM

Hi guys,

I've been searching but could not pinpoint a thread related.

My S4 has been acting weird. After 20-30 minutes of driving my boost is stuck at 5.2-5.3 PSI. Like it is in limp mode. I checked for boost leaks. I couldn't find anything. Throttle body boot seems to be good.
First thing in the morning, or driving when it's cold, it seems to be fine. Boosting around 17PSI.

No codes. No cel. Car runs and drives fine as well. Just the boost cuts when it is hot.

I am thinking anywhere from N75, Throttle body adaption?, or Heat soak from intercoolers?

Current modes:
Stage 1 - GIAC tune - oldschool chip with chip soldered into ECU.
SSAC Twin 1 - With downpipes

Any help or if anyone could point me in the right direction, that would great. Thanks in advance.

Thanks

Mike

**CELison** · 04-30-2018 09:19 AM

You need to see what code is throwing it in limp mode. Anything else is just a guess. Scan your car.

**TooDamnFresh** · 04-30-2018 09:35 AM

Originally Posted by CELison

You need to see what code is throwing it in limp mode. Anything else is just a guess. Scan your car.

That's the thing. There are no codes. No DTC's. No CEL.

**TooDamnFresh** · 04-30-2018 03:55 PM

Anyone experience this? I am planning to start with N75 even though there are no codes, DTC, or CEL. Or is it pointless just throwing one on there?

**Schtug** · 04-30-2018 04:29 PM

Almost strikes me as something getting flagged towards the end of a drive cycle. Can you pull up the readiness monitors on vag com while you're driving and see if there anything fails around the time it stops boosting normally?