Boost spike problem, with video..(fixed page3)

[r8byb]

Hey guys, tonight i noticed a bit of a problem, when my boost spikes above 20 psi it seems i get a kind of missing sort of noise, then it goes into limp mode for a few seconds then it will let me fully boost again...

Best shown and heard in the video here

http://www.youtube.com/watch?v=i4O5m1sYwOc

THis is the car straight after doing 40 - 120 without it doing it, not fully pushing it and 3 up aswell.

http://www.youtube.com/watch?v=uy__s5TZHgQ

More detailed description>
when at say 2k revs in 4th, put foot down its fine until it gets past 20 psi then it will make a sorta of brrrr brrr noise, then go into limp mode for a few seconds.

However if im in 4th and boot it when its at 3.5k rpm so it doesnt have to spike as much its find and doesnt make the brr brr noise at all.

Mods are full stage 2, n75 race valve, n249 bypass done aswell, oil and filter change about 5 k ago, plugs about 9k ago, forge front mount, split R, TIP, full blue flame, new Maf about 2 months ago, no warning light coming on either.

Any help is appriciated.

Rob

 

[r8byb]

Going to change plugs tomorrow as they havent been done for a while, and im still running standard plugs not the range down ones that you should fit when you up the BHP 50+ so could be that ? Video is pretty self explantory and shows the problem perfectly .

 

[Adam R]

sounds like the turbo is over boosting....

1) if you have your foot flat to the floor and pull through the rev range with boost increasing, does it cut out like your hitting some sort of limiter when the boost spikes ?

2) if your slightly off WOT (Wide Open Throttle) so say about 90% throttle it does not occure..

if those 2 statments above are correct then you are deffinatly seeing an over boost situation. not sure how to fix it though as i dont have a 1.8t.

 

[Pky]

have you vag-com'd it? I have the same gauge....

http://www.youtube.com/watch?v=BG6iDYfs_kA

Im stage one, but if you look, its sort of doing the same thing.... now that was due to the car being mapped wrong, plus the guage was fooked, so that wasnt an acurate reading... (Yes, I know its upside down)

http://www.youtube.com/watch?v=llBIYhPiZ3o is what my car is doing after the map has been fixed. vag com is staying im boosing more then 10PSI tho.... and the RR results I got, I would think I was boosting higher too...

Might wanna Vag-com and see what your 'Real' Results are, where is your guage plugged into btw? (They were taken from I was ontop of the D.V) now its on the FPR.

 

[r8byb]

well its on boost 9 timing 7 on a ko3, stage 2 revo, what Adam said is kind of correct, but surely if it was fine for the last 1000 miles something must of gave up the ghost.?

And i have no access to vagcom at all , mate's have been saying coil/plugs, cause if it was overboosting, surely it would stay in limp mode longer than like 2 seconds or so..?

 

[Pky]

yeah, when my car was underboosting it would go into limp mode and stay there until the car was turned off/on again... thought Stage 2 was for a ko3s ?

 

[r8byb]

No stage 2 is fine on a ko3 its been like it for quite a while , i dont have to turn it off.

You can see in the first vid where it makes that brr brrr noise it then drops into limp mode then i let off put my foot down and its back round to 21 - 22psi boosting fine.

Just to elborate on what i said about Adams reply, if im at 100% throttle, and the car is at 3k revs doesnt have to spike above 21psi ish it goes fine, if im at 2k revs and then go 100% throttle is when it does it.

 

[truCido]

the n75 is usually a culprit of some issues with overboosting, do you still have the standard valve you could try? also like mentioned above an agressive map can obviously cause overboosting

 

[r8byb]

think i do have the old n75 valve around yeah, could it be cause the whether was really cold last night is the reason it was doing it ?
Im going to get my boost turned down so it peaks at around 22psi cause running HB9 on a ko3 is a bit silly i think

 

[truCido]

ummm i wouldnt of thought the cold would of affected it but you never know!!

yeah 22psi peak sounds about right for a Ko3, would be good to get a few logs done on vagcom though and see exactly whats going on

 

[PhilW]

Has the actuator been touched? Overboosting it sounds like from the description, but i cant see the video to comment.

 

[r8byb]

I remember my mate posting up a thread, when he owned it saying that it seemed to boost 2psi more standard than it should do and thinking the actuator may have been adjusted ? is it 12 - 13 threads that should be showing ?

Cause ill check that at lunch and see what its showing, cant do any logs as dont have vag-com


Hopefully someone who lives near with a revo controller will be able to knock it down to HB7 T7 for me so it spikes at 21 - 22psi max..

 

[Olly20VT]

I had this and just turned the boost down a touch, also my car is boosting more in the cold because it's denser air so this could be you're problem. Also you're car will take some time to adjust to any changes so this could be why it's be OK for 1k miles first.
Changing the N75 back to standard might be a good idea to try.

 

[r8byb]

Ok thanks Oli, ill try and get the boost turned asap then, when i say a 1000 miles, ive done a 1000 my mates done about 3 - 4 k since it was all done and he had a problem with the MAF and had to change that but nothing like this at all.

Reckon get it turned down to Boost 7 rather than 9 ? Or lower ?

Also out of curiosity, its probably just me, but it felt slower yesterday too, Does the video of 40 - 120 look abotu right for stage 2 ? was 3 up mind..

 

[rhysox]

i have this same problem with my ibiza.. i never know whether it's going to be rapid or just like a normal car. need to get it logged properly. i had my car vag-com'd by phil, and it came up with overboost. but i don't even know whats been done to my car in the past.

it's a bit of a lottery when you put your foot down, it'll either pull very hard and then go into limp mode, or be about as fast as a standard cupra. i've got a feeling that my actuator has been played with and the map isn't suited. but i'm no expert. need to get it logged! but next on the list of things to do is a new n75 valve.

sorry to hijack your thread r8byb!

 

[longman]

Its definitely worth changing back to the original N75. The J or Race versions are known to give boost spikes and cause limp mode.

The cold weather will make a difference to power as its denser but I think the ECU will account for that and if not the difference in pressure would be negligabe, it will just get there quicker I think.

If you are near me, I could do some logs for you if you like.

 

[ibizacupra]

you need to log the thing to see whats happening.. invest in vag-com or find someone who has it and the time to lend etc..

turn it down to boost 6 ign 4 (95UL) or igb 6 (98UL) and see what its like.
less is more oftern more... but without logs, its blind diagnosis

 

[r8byb]

Ok cool,

Just a bit of an update aswell... Just been having a play, had it peaking at 26psi and not doing it then, had it peaking at 25 psi in 4th and is it was dropping down the boost after peaking it did it, not before it peaked..

If i drive it quickly it doesnt do it at all, like if the revs are always above 2.5k - 3k...

Ill try and get the original N75 valve and refit that then, and get the boost turned down cause like you say running 26 psi spiking isnt doing naff all really, it feels just as quick when i keep the rev's up so its only peaking at 21 - 22 psi max, just cant understand why it does it, doesnt seem to do it in 1st or 2nd, or 5th, like i say it pulled hard in 5th and peaked at 25. its 3rd and 4th it's doing it in at around 3000 RPM but ONLY when boost spikes higher than 23psi

EDIT: Just spoke to my mate, he says hes never seen it peak at 26 psi before 23/24 being the highest he has seen, doesnt have the old N75 its running a "J" valve now.

 

[r8byb]

My mate has trial version of vag-com hes going to plug into my car tonight ?

What log does he need to do ? and can the trial do logs or help at all ?

 

[ibizacupra]

its load based hence not doing it on light loads in lower gears.
deviation from actual and requested boost likely - hence liimp.

trial version of vag-com does'nt log tho does it?