Wierd problem - please help (yes already replaced the MAF : P)

[sonic_vi]

would it still detect a boost leak though

i mean it is terrible with MAF plugged in, bogging down badly and jumping to life randomly

actually seems worse since i changed the plugs ironically after driving it for a bit

 

[DPJ]

No, I don't think it would detect a boost leak - but I'd bet money your problem is your MAF.

 

[sonic_vi]

ok been doin some logging with VAG-COM

(or been learning how to use it properly )

The MAF sensor seems to be logging ok

with RAIDHP maxflow induction kit the idle air mass in is sitting around 4.5-4.7 g/s (high end of normal but there is an induction kit on it) peaking at 166 at its highest point.

the most disturbing reading is the requested boost and actual boost under load

a particularly bad example is

requested boost - 1860 mbar
actual boost - 1320 mbar

this is obviously a leaky hose somewhere although i can't find it

Run o2 adapt is sat at a constant -0.8%

idle o2 adapt is sat at -6.4% for ages and then goes up to -7.1% after a bit.

any clues on which hoses are gonna be favourite?

also what do you listen for?

is there an obvious hissing from where its leaking

i am dropping 1/2 a bar under load at the worst point in soft limp mode so must be a big hole somewhere

 

[Saul]

vacuum hoses as said (the smaller hoses) are popular

also check the main hose from the airbox onto the turbo

apart from that listen for leaks, as said before a trip to awesome and maybe half hour on the rollers would find your leak

 

[TheOtherSimon]

Plugs are quite common - the number of cars that mysteriously get better after the 40k service is remarkable.

It can also be a bad batch of fuel. If you have been using 98+ octane fuel for a while, it will run like a dog on 95. This seems to occasionally occur when the petrol station puts the wrong fuel in the wrong tank.

Air leaks are very common on VAG cars over six years old, and tricky to trace.

Simon.

 

[sonic_vi]

Booked in at awesome for monday

i went to sleep last night and all i could see was VAG COM logs when i shut my eyes

 

[sonic_vi]

Plugs are quite common - the number of cars that mysteriously get better after the 40k service is remarkable.

It can also be a bad batch of fuel. If you have been using 98+ octane fuel for a while, it will run like a dog on 95. This seems to occasionally occur when the petrol station puts the wrong fuel in the wrong tank.

Air leaks are very common on VAG cars over six years old, and tricky to trace.

Simon.

methinks it will be the latter of the 3

plugs have been changed 2 days ago

car only ever runs on 95 RON fuel (reason for this is i use the car for work and my fuel card will get cut up if i drop super in but all my personal milage is covered so i can deal lol ) plus its been doing this for a while and i fuel up about twice a week

all thats left is a boost leak.

don't think its a VAC leak looking at the vag com readings as the fuel trim adjustment is within normal parameters.

one thing i will say is my mate found that my EVAP purge valve is clicking all the time like a crazy thing doesn't do it on his octy vrs

 

[sonic_vi]

GOD DAMMIT ! FRIGGIN NEW MAF WAS FAULTY !!!

bottom readings were fine, top readings were fine, in between was basically a random box of frogs

sent back

if its 37 quid delivered off ebay there is probably a lesson there somewhere.

the epitomy of buy cheap buy twice

bought a MAF from GSF (genuine) 76quid exchange and had to buy an hour of diag time at awesome so £££

but sorted now

 

[DPJ]

GOD DAMMIT ! FRIGGIN NEW MAF WAS FAULTY !!!

bottom readings were fine, top readings were fine, in between was basically a random box of frogs

sent back

if its 37 quid delivered off ebay there is probably a lesson there somewhere.

the epitomy of buy cheap buy twice

bought a MAF from GSF (genuine) 76quid exchange and had to buy an hour of diag time at awesome so £££

but sorted now

Glad you got it sorted.

 

[Saul]

hard luck to learn the hard way, but a lesson learnt all the same and at least the car is fixed