no boost then hits boost hard

_scotty_

New Member
I have never own a gtir before so this may be a common problem but I'm unsure so need some advice. When I put my foot down I can hear the turbo spooling up from 2.5k but it's not working then higher up in the revs 4-6 it works but its not a gradual It just comes on hard if that makes sense. I know its not right because sometimes it will try to work from 2.5k but it cuts the boost then works again later on.could this be the boost control sensor?

The car is running a big fmic, air filter, dump valve and a manual boost controller set to 1bar which it will hold when it works.

Any help or advice appreciate
 

shroom

Active Member
I have never own a gtir before so this may be a common problem but I'm unsure so need some advice. When I put my foot down I can hear the turbo spooling up from 2.5k but it's not working then higher up in the revs 4-6 it works but its not a gradual It just comes on hard if that makes sense. I know its not right because sometimes it will try to work from 2.5k but it cuts the boost then works again later on.could this be the boost control sensor?

The car is running a big fmic, air filter, dump valve and a manual boost controller set to 1bar which it will hold when it works.

Any help or advice appreciate
As Whytie said do a fault code check

http://www.gtiroc.com/forums/showthread.php?20463-Fault-code-check-procedure

Try to isolate the problem, your fmic could have a boost leak so check your pipework and silicone hoses for splits or if they are badly fitted , you could have issues with your dump valve opening up too soon so maybe if you don't get any luck with the fmic try taking your dump valve out and block it off. I have had these type of issues in the past and fmic/dump valve can create issues.
 

_scotty_

New Member
Thanks I will check over the pipe work tomorrow. As for the fuel pump I know it was changed but don't know if its standard or uprated and the dump valve seems to be working fine. It feels like a sensor cutting the boost tho, I will read the fault codes as well but theres no eml on.
 

shroom

Active Member
yeh if its the nock sensor it will cause the car to go into limp mode and restrict it. From experiance its not always cut and dry so it can cause weird problems such as your symptoms. I had a split pipe and it would jump into limp mode at 2.5-3k
 

Fusion Ed

Active Member
Scotty, these cars need to have major faults for the ecu light to come on. I'd get the car to a dyno if I were you and check its ok. Hesitation or holding back can often be fuel related. Its not worth a blown engine.
 

KieranEG6

Member
Had this exact fault on my old Impreza turned out it was the turbo wastegate seized slightly open. Started spooling at 2k ish but would take till 4k to finally get onto boost then would come in hard and sometimes over boost on really long hard pulls in 5th.

Might be different fault but symptoms are same, I just plastered some WD40 down and around the wastegate penny shaft then worked it open closed with Pliers.
 
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