1.8t help

Hi... Anyone near Hitchin got a vagcom and expertise to help me diagnose a potential problem? Will pay in beer if required!! ;-)
I've got a slight surging issue on boost which has apparently been looked at by the garage (nothing wrong) but I'm sure is something. It's probably throwing up a few codes and I want to check.

Thanks in advance, hope someone can help...

X

Sorry I don't have one but was just wondering what if anything you have done to resolve it?
Sometimes boost surges are caused by leeks...you could also try swapping the N75 valve and see if that makes a difference. Has the car been mapped?...also what petrol do you use? Does it start to stutter when it surges? as that could indicate wrong spacing in the spark plugs.

Steph.

Hi - nothing yet but it's been to the garage with no apparent faults found. I've checked most of the visible hoses, done the MAF unplug test and it still doing it. It doesn't stutter but it's kind of slowing in acceleration then picking up again after a second. All very strange.

It's absolutely standard at the moment, normal unleaded

Where can I get a N75 from? Which is best and is it something a noob like me can fit?

By the way I've had ALOT of Mk3s and can pass on plenty of advise on those - these 20vTs are completely new to me!!

Cheers

I see you have already seen Mr Calimori N75 post....this could be the issue and I believe that it wont throw up anything on the VAG com either.
When you say normal unleaded petrol...have you tried super unleaded? My car hates normal unleaded even before the map...might be worth a shot.

Cheers Pinky, I will give it a shot next time I fill up... still going to look into the N75 thing though!!

Put it this way - blew out a Type R on the way to work today - its definatly rapid!! :-)

haha nice one

OK, lets start with what your car is and work from there. I have VAGCOM if you are willing to travel to my house at some point.
Once I know what your car is, we can always test with another one of the same or try bypassing it with a boost controller I have lying about somewhere.
Best way to spend some money to help us see real time what is going on is to fit a boost guage, even a £30 jobbie from Halfrauds will show us in real time what is happening. Make sure it also shows vacuum as there is a world of problems there too.

Hi there - it's a 2002 AUM - I was thinking of getting a boost gauge, sOmething subtle though - are they easy to fit? Yes I'm defiantly willing to travel - whereabouts are you?
Thanks again.

Ok - quick update - we connected it tonight and the only fault code was from when I disconnected the MAF. It's boost pressures are all fine, so it's likely to be coilpacks or N75 valve. Good news was apparently my AUM probably has more than the 150 Horses it should have... :-)

yay

All good... and I checked the servicebook and it looks like the spark plugs were last replaced 4 years ago when the belt was replaced - its only 20k miles since then but in terms of time and 'use' I think i'm going to do them first, then coil packs then N75.....

New spark plugs fitted! old ones were knackered! Has made a big difference....

splendid good work mate.

Yaaaaaaay!

Yeah its much better.... Its still not 100% so I think I will do the coils next... the mechanic mentioned that the N75 valve might be slightly sticky (spring?) - if this is not functioning correctly (But not faulty) is it likely to NOT throw up error codes? Currently I have no error codes - the only one was from when I unplugged the MAF to test it....

If its the N75 then I have to choose which one to replace it with - bearing in mind I might get it remapped to about the 180 mark.... :-)

Sounds like the n75 mate. You might have a boost leak thats affecting the n75's ability to open/close. The vw ones are pony anyway mate if your going to get it mapped, just upgrade

Its probably best to either replace the valve or do what Calimori said and fit a boost gauge so you know if your loosing pressure.

Yeah cheers - we took it out connected up to the VAGcom and it was receiving and outputting the correct pressures... so its pointing towards the N75.... Can anyone recommend which one is the best to buy?

Thanks

Sadly Vagcom is not able to read the signal often enough to really know what is happening due to the slowness of the ODBII port.
I bought a cheap halford sold boost gauge but make sure it has vacuum as well so we can check if the PCV pipes have perished as that will show as a vacuum leak.

Swax wrote:

Yeah its much better.... Its still not 100% so I think I will do the coils next... the mechanic mentioned that the N75 valve might be slightly sticky (spring?) - if this is not functioning correctly (But not faulty) is it likely to NOT throw up error codes? Currently I have no error codes - the only one was from when I unplugged the MAF to test it....

If its the N75 then I have to choose which one to replace it with - bearing in mind I might get it remapped to about the 180 mark.... :-)

I'm getting my Leon mapped in the next few weeks a few of my mate have been mapped guy this guy and are well impressed and he only want 140's.

Really? Sounds good - does he have a RR and do diagnostics too?

No rr but he will diag. My mate hade his Cupra done by him rollered it a week late and and from the stock 180 bhp he is now running 210 and the only engin mod he has is a split r silicon tip and an open cone and it's not a horrible map it's fast and smooth not to agresive.! I'm hopping for 225/230.!

The place I used near Stansted had RR and were very knowledgeable.
Sort out the car first or the remap can make things worse. If you are running standard hoses they might not leak at 7PSI but are very likely to not fair as well as 14.5 which would be the ~210 mark. Mine spikes at 18 PSI at current but drops due to a weak actuator.

I'm all siliconed up now big fmic N249 bypassed. And running 197.8 that's without a map.!!!

What is your boost at the moment?

10 psi.