Boost issues..i think

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Black_S3

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Hi All.
I've owned my S3 for little over 6months now.It has a custom remap,forge DV and i've recently installed a TIP.The car goes through the first 4 gears pretty rapidly,but in 5th at about 5000rpm it seems to lose boost.This happens in 6th also,feels like it's just revving with no power.The DV still has the standard spring it came with and my peak boost according to VagCom is 1.4bar at about 4000rpm,should i be changing to a yellow spring as suggested on the forge website?For the first time since owning the car i caught a nissan (sr20) on the highway,i thought it would be a walk in the park.Through 2nd to 4th i maintained,but in 5th he leveled up and we tapped.I definitely think the s3 is stronger in 5th and 6th than mine currently is.Any suggestions would be appreciated.
 
A standard S3 runs around 12psi of boost and depending on your remap you'll now be runing close to 20psi. If the 007P recirc valve comes as standard with a green spring then it would be worth your while getting a yellow one.
 
cant see the spring causing this issue TBH..... i had a similar problem with losing top end boost ages ago...traced it to a T piece on top of the engine rocker cover... personally id check all pipes above the rocker and below the inlet manifold and to the left of the cam belt - then move on from there, obviously try unplugging the MAF and drivng to see if that makes a difference also...
 
Tougher spring will make no difference at all if you are running the valve in the standard orientation.

Log duty cycle and requested against actual boost to see if the car is producing what the ECU is wanting.

If the ECU is requesting less, then there is nothing you can do particularly. Look to see if timing is backing off and air inlet temps.

The stock N75 is just pants to be honest. Check the stuff animal mentions.
 
Thanks, will check all the pipe work.
From my last Vag session, my requested vs actual boost is pretty spot one, only deviated slightly towards 6000rpm, but nothing major. Also the test was conducted in 4th gear and 5th and 6th is the problem.
I did notice that intake temps have increased on average from 38degrees to 49degrees.
Trying to get my graphs uploaded.
 
Here we go:
This is post remap
requestedvsactualboost.jpg


intaketempbeforeafter.png
 
HTC said:
Tougher spring will make no difference at all if you are running the valve in the standard orientation.
Click to expand...

So are you lot with remaps running the yellow spring or still the standard green spring? I was under the impression I would need to upgrade the spring as the green one is rated upto 15psi?
 
if its throwing boost at the top end it could be one of the electrics id have thought..... im no expert but N249 valve, N75 etc etc.... its not doing it at peak boost which is typically your 3rd gear from what you've said so no simple solution i dont think
 
the spring issue is negligable compared to whats wrong with your car id have said.... if the DV isnt new id suggest cleaning it too as a precaution
 
1animal1 said:
the spring issue is negligable compared to whats wrong with your car id have said.... if the DV isnt new id suggest cleaning it too as a precaution
Click to expand...

Yeah sorry I was kind of hi-jacking the thread and asking the question in general (for myself)! Though looking back on my boost graph it seems to be holding peak boost ok. Are you running the yellow spring Tim?
 
na westle i have a standard DV.... dont see the point in changing...... £20 for a new OEM or £80 for the forge.... i have a spare OEM too, im still on original one12 months after the map
 
Pressure under boost acts on the side of the piston on the forge valve. A tougher spring won't make you hold more. Tougher spring will make the valve faster and dump less. I've run the green up to 30psi no problem. Everyday boost for mine is set at 22psi.

You are probably pulling a bit of timing in 6th. This is where you'll see the largest intake temps if full throttle for a while. Log 6th if this is where the issues are.

I don't think you are loosing boost. Remember the K04 does run out of puff in the higher revs.
 
Did you feel the power drop off when the airflow dropped back?

You should log, airflow, boost and timing pull all at the same time to get the best idea of what is going on.

Gavin
 
Yes i have reset the throttle already.My tuner seems to think its cos my requested boost vs. Actual boost is a bit out.Ie: from about 3200rpm - 4300rpm its requesting 2410mbar but actual is aroung 2540mbar.
 
Black_S3 said:
Yes i have reset the throttle already.My tuner seems to think its cos my requested boost vs. Actual boost is a bit out.Ie: from about 3200rpm - 4300rpm its requesting 2410mbar but actual is aroung 2540mbar.
Click to expand...


What remap do you have. My ChippedUK map requests stupid boost that the turbo can meet but I dont have the problems that you're having.
 
Remember the ECU has the ability to close the throttle body, open the DV etc at will. All part of the self protection.

I would log timing pull (rather than overall timing), mass airflow, lambda, air inlet temp etc. You need to see why it's closing the throttle.

The map might need tweaking to allow wider parameters. Might be something as simple as a bad MAF.
 
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