Boost Issues.....finally sorted...strange symtom though

[M87NER]

Hi There,

Could do with some help here....

noticed other day (has done this before aswell) when driving up a hill in 4th (only noticed in 4th so far... could happen in 5th-never tried ) gear from about 1500 revs building up the boost but when it hits ~12psi it drops down to ~ 0-5psi and have let my foot of accelerater and back on to let it boost back up again, any ideas why this is happaning...

i know i need some new coilpacks when i can offord get all 4 but this wouldnt cause this misshap would it?

Cheers

Matner

 

[ian_cupra]

sounds like a little over boost????

 

[jay26]

mine dose this too thort it might be weak actuator

 

[clinch]

mine does the same it boost to about 22psi but the higher up the rev range you go the more the boost backs off some times its ok a friend has suggested n75 valve but would i be right in thinking this is a week/poor actuator ?

 

[M87NER]

sounds like a little over boost????

would it over boost if it was only hitting 12 psi ......?

 

[MIkey kc]

would it over boost if it was only hitting 12 psi ......?

i spose it might do because if the ecu wants to see a certain psi at that rev range it could put it into limp mode but i anit too sure. i had this when air/fuel mixture was wrong before my map?? you could try to get hold of a stoichiometric gauge cheep and just wire it into the lambda probe to see what air/fuel mixture is lean or rich when it does it? just an idea

 

[jay26]

ill try and manual boost controler and see what happens as this will bypass the n75

 

[dai cupra]

n75 i had same prob on mine so changed it and now fine

 

[ibizacupra]

limp mode is what you describe, and boost deviation code would likely have been thrown

 

[clinch]

right how do i go about sorting this ?

 

[Robbie C]

I'd start with a VAG COM scan for fault codes and then maybe post a few logs up if that doesn't give you any clues so we can see what your readings are like

 

[M87NER]

scanned the car but no faults came up, had the eml flash 6 times lastnight when i accelerated hard in 2nd gear as it was miss fireing, would the wrong type of spark plugs cause this as i have ngk bkr6e instead of the bkr7e ... or just go straight to coilpack...

cheers

 

[DaNnY_LaD]

Coilpack failing Under WOT on boost?

Wont so a code as it isnt completly Dead yet

 

[M87NER]

replaced all coilpacks and fitted bkr7e's and car desnt miss a beat..... but still get this cut of boost...

seems to do it when i accelerate and the boost has to build up from low rev range and when it hits peak boost it drops down abit to about 10 psi then hits peak boost again and holds it this time, is this still the n75 then... might try a manual boost controller if i can get hold of one,

 

[Robbie C]

Log VAG COM block 115 - actual boost vs specified and that ought to give us some clues

 

[__B3NNY__]

When speaking to Bill about mapping my hybrid he mentioned that hybrids like to spike so he would like me to bring an MBC along with me just incase, so maybe try getting an MBC and setting up.

I would have thought it would have done this when spiking on boost not at 12psi?

 

[M87NER]

will have try them logs then, tried a MBC today and couldnt hit above 20psi even with it fully wound out....even half wound out it was getting 22psi on my mates cupra... so bit confused about that...

 

[DaNnY_LaD]

Have you ruled out a boost leak matner?

 

[M87NER]

Have you ruled out a boost leak matner?

nope, havent thought about that really

 

[DaNnY_LaD]

That would the first thing id check tbh to rule it out....