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Turbo overboost condition?? (please help)

Tcobb52

New member
Sorry for the long post!! I just want to give as much info in hopes that someone may have some answers for me.

Lets start off with a little bit of context. Car is a 2011 GTI, 105k miles. I have Cobb stage 2 w/ accessport, pflo intake, 3" catless dp and 3" custom exhaust. Turbo outlet pipe and throttle body pipe have both been upgraded to the larger ones.

Okay, on to the problem, I had a leaking oil cooler, and bad intake manifold replaced over the weekend. Anyone who has done that job knows that oil and coolant will be all over the place in the engine bay. Wednesday I finally got around to cleaning up all the mess on my lunch hour at work. I didnt do anything different than what I normally do for an engine wash, covered intake and alternator, only used light pressure running hose water (not a pressure washer), engine degreaser and some soft brushes.

Normally I would leave the car out to dry after but it started pouring rain so i hurried up and hosed off what was left, removed the bags, and pulled the car back to where my parking spot is.

After work I started my car and everything was fine...until I pulled out onto the main road and thats when things started going downhill. My Car went into limp mode and I pulled over and ran the codes. p2178, p0234, p0236, p0237 Showing system rich at idle, turbo overboost and underboost, and boost pressure sensor. I cleared the codes and slowly creeped home as I was only 3 miles away. I cleared the codes when I got home again and went over the majority of the system pulling each sensor checking for water or broken wires, checked for torn hoses and everything as well. Could not see any visual damage or water.

After Checking everything out I ran the codes again, and am currently only getting P0234 for Overboost, and P038 for boost sensor. With the ignition on, car off, I am showing 23 psi on my accessport!!! I did some research and to my knowledge the MAP is the sensor associated with those codes. I pulled the MAP sensor plug and cleared the codes and scanned again. The same two codes popped up again, and I am now reading 0psi boost. My thoughts are a bad MAP sensor and I have a new one on the way.

Am I on the right direction, or am I missing something?? Car will not even run as of right now. I can turn it on and it bogs immediately and shuts off. Any Help or input would be greatly appreciated. Thank you in Advance.
 

FriggenT1

Banned
Did you clean the map sensor with a brake cleaner or electric cleaner that dries up quickly? Did you blow on it to make sure no water was present? I don't know how accurate the AP is with boost pressure. My old AP would never read on par with a standard mechanical boost gauge in my evo or wrx. You're positive you do not have a vacuum leak anywhere correct? If it just bogs down and cuts out, it really sounds like a large vac leak. If you were running 23 psi as you said, a hose could be blown off and caused that too possibly. Intake manifold is bolted up and torqued to spec? You didn't for get to tighten the clamp at the TB either?
 

Tcobb52

New member
Did you clean the map sensor with a brake cleaner or electric cleaner that dries up quickly? Did you blow on it to make sure no water was present? I don't know how accurate the AP is with boost pressure. My old AP would never read on par with a standard mechanical boost gauge in my evo or wrx. You're positive you do not have a vacuum leak anywhere correct? If it just bogs down and cuts out, it really sounds like a large vac leak. If you were running 23 psi as you said, a hose could be blown off and caused that too possibly. Intake manifold is bolted up and torqued to spec? You didn't for get to tighten the clamp at the TB either?

Thanks for the reply.
I did not use any chemicals to clean the MAP sensor as I was afraid that they would damage it. I guess at this point though It wouldnt hurt to try, as my New one is still slowly making its way via usps.
I was never running that high boost under normal driving conditions. The max I have ever read on my Accessport was 19.8psi.. I pulled the underbody tray and checked all my hoses in any area where I may possibly have a boost leak. I could not find any. Unless I somehow cracked my intercooler which I dont see happening that easily. Throttle body hoses and intercooler hoses are tight and intact, intake manifold was torqued to spec and everything was thoroughly checked over when I did all the repairs.
 

FriggenT1

Banned
So there was no oil coming from any connections? IC hoses, at the turbo outlet? TOP? That hose from the turbo to the vac line on top, next to the oil cap? That's an easy one to miss.
 

Tcobb52

New member
So there was no oil coming from any connections? IC hoses, at the turbo outlet? TOP? That hose from the turbo to the vac line on top, next to the oil cap? That's an easy one to miss.

Correct, there was zero oil around any of the connections. I drove several hundred miles since the oil cooler repair and intake manifold swap. I also had zero issues driving to work that morning.
 

FriggenT1

Banned
Correct, there was zero oil around any of the connections. I drove several hundred miles since the oil cooler repair and intake manifold swap. I also had zero issues driving to work that morning.

Welllllll, I guess just wait for the map sensor and see if that makes a difference

Edit: coils are plugged and snapped too right? Also the plugs were checked ?
 
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