Boost pressure issues

Sisson

Club member
Aug 18, 2005
1,662
0
Derbyshire
Hi all

Stage 1 ayp cupra,

Boosts to around 16psi in gears 2 to 5 yet sometimes it only boosts to 11psi.

Any ideas why it does this?

Thanks
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
load determination... which could be maf based, or physical component malfunction like n75 have a "moment" etc

any faultcodes logged?
 

Sisson

Club member
Aug 18, 2005
1,662
0
Derbyshire
Now it won't go over 10 psi at all. Will run vag com later see what codes come up, any ways to check n75 or maf in the mean time
 

Sisson

Club member
Aug 18, 2005
1,662
0
Derbyshire
I've just ran it with maf un plugged, it boosted to 11 maybe 12 psi in 3rd and 4th and made the idle a bit lumpy but still drove well.

Would this indicate its a duff one?

Is it measuring blocks 003, 008 and 115 on vcds?
 
Last edited:

Sisson

Club member
Aug 18, 2005
1,662
0
Derbyshire
Right, tried to log 003,115,118 would only let me do 003? Says I need to register my vcds to log the others?

Anyhow could only manage a quick run in 2nd to redline and the maximum max reading was 69.4 g/s?

Is it me or is that really really low!
 

Sisson

Club member
Aug 18, 2005
1,662
0
Derbyshire
Why am I only getting 70g/s max? Tried original airbox, which is still the same.

No fault codes? 10psi max maybe hits 11psi in 4th.

Do I need full vagcom to log 115 and 118?

Checked vac pipes and boost pipes, all seem good, going to make a leak tester and see if I can find any leaks, which pipe do you clamp to stop pressurising the crankcase?
 

Sisson

Club member
Aug 18, 2005
1,662
0
Derbyshire
Yeah was maf sensor, boosting at 16psi now,

Although the odd time it only boosts to 5ish but when I lift off and back on throttle it boosts fully again???
 

waky

Active Member
Dec 2, 2014
2
0
This sounds like the same problem I have, done the n75 so trying maf next, hopefully it'll cure my car too!!


Sent from space X
 

boostjunkie

Active Member
Nov 26, 2014
13
0
Did the maf also cure yours waky I have same problem with last night and again today was boosting at 12psi now not holding and dropping to 8psi would this also be my maf just happened when I was overtaking some one boosted in 3rd then dropped to 2psi? Anyone help new to the forum I was told it's had a stage 1 map does 12psi sound right what it should be running in the first place. Thanks
 

Sisson

Club member
Aug 18, 2005
1,662
0
Derbyshire
My stage 1 map is peaking 15/16 psi dropping off to 11/12psi at redline.

Mine keeps randomly dropping off, it's either a boost leak on fmic pipework or my standard dv leaking.
 

boostjunkie

Active Member
Nov 26, 2014
13
0
I unplugged mine tonight and was definitely quicker and boosted more does this mean that I need a new maf or would it do that anyway?
 

boostjunkie

Active Member
Nov 26, 2014
13
0
Cheers for that mate I can order one today now are the cheap ones on eBay OK or would it have to be a bosch on edits just they are £25 and bosch are like £100 Thanks again