over boosting

[-alfy-]

Hi! Ive spent some time searching the forums to try and find an answer for this but to no avail.

Basically i normaly peek boost at around 14psi, last night on my way home i was peeking at around 20psi and with alot of spluttering.

This morning im boosting up to around 20 psi again but no splutter.

Ive checked the vac hosing but cant see any splits. Im really baffled on what the problem could be!

I recently had a service including spark plug change. Could this be the problem?
duff plugs breaking down on heavy load?

thanks in advance

 

[GlanzaV]

I was going to suggest the colder weather would cause it... but not as much as 6psi I wouldn't have thought?

 

[-alfy-]

no I can't see it being that. As the engine management light hasnt come on,will there be no fault codes?

 

[carlos200]

i was actually gonna post up about a similar situation, not quite as much as 6psi tho... lol

normally i would peak about 21psi but its goin upto 22-23psi sometimes, misfires then continues boost.. assuming this is cos of the weather and the threshold limit for boost has been reached and therfor misfires?? or am i totally wrong.. lol.

 

[-alfy-]

driving this morning, and in third i peeked at 14psi fine, went into 4th and up to 20psi then came the splutter.

a couple of my vac pipes were missing the cable ties, so ive put some more on, hopefully this could all be down to a bit of boost leak.

 

[Dan.Payne]

Your car look familiar? what map are you running? Does it not drop into limp mode at all?

 

[-alfy-]

AmD remap.

The car was my cousins and he was on here

 

[Dan.Payne]

ah cool, think we was on the GTI international stand last year but then had a bump? I thought AMD should be about 20psi on stage1? I would unplug maf and take it out see how it runs then.. but a VAG COM scan will show your problems.

 

[p34ch3y]

duno if this helps but my jabba map is 19psi

 

[Adam R]

14psi is very low for a peak isnt it ???

i thought a normal boost spike was around 21psi for the cupras ?

 

[p34ch3y]

yea 19psi to 21psi i think

 

[rhysox]

i have a stage1 cupra with AmD map, it 'overboosts' all the time. very annoying...

75% of the time, it's fine, will run normally, pretty quick etc, then sometimes it feels MUCH quicker, and then the turbo seems to just turn off, i.e. does not boost. checked with vag-com and it came up with overboost. To rectify this you have to turn the ignition off and on again, and then it boosts fine.

going to get a new remap soon i think, but after i get a k03s

 

[rhysox]

unless it could be a problem with the MAF/n75/n249?

i have no idea about what n valves do, but i understand that they can cause problems on modified cars

 

[p34ch3y]

unless it could be a problem with the MAF/n75/n249?

i have no idea about what n valves do, but i understand that they can cause problems on modified cars

yea it could be anyone of them three valve..most probly the n75 if its a boost thing altho the maf my do it,

i am also haveing the same problems at the mo,i got a new n75f valve from vag parts but we think the new one is foo bard too so that has been sent of to be tested.....my maf is fine and the n249 is bypassd anyway.....so saped the n114 valve a couple of time to see if that made a diffrence but it dnt.....im starting to think im haveing probelms with my map

 

[rhysox]

i really need to learn what all these valves do... i'm pretty sure i've still got my n249 valve. n75 is the original F i think, and MAF is probably original. 7 year old car too!

 

[p34ch3y]

if its an original n75 it will be a n75C

might be worth getting the MAF checked

 

[Beaker™]

i really need to learn what all these valves do... i'm pretty sure i've still got my n249 valve. n75 is the original F i think, and MAF is probably original. 7 year old car too!

7yr old MAF! Im surprised you car boosts al all! I'd get the airflow logged just to rule that out.

 

[p34ch3y]

7yr old MAF! Im surprised you car boosts al all! I'd get the airflow logged just to rule that out.

agreed!

 

[rhysox]

hm, yeh that's probably a good idea. would like to know what sort of boost it's running too.

gonna have to give philw a shout, see if he'll take a look again. cheers guys

 

[__B3NNY__]

My money would be on the maf.