only 10 psi!!!

M

malcolm30029085

Registered User
Joined
Nov 29, 2009
Messages
55
Reaction score
0
Points
6
Location
NULL
can anyone give me some help plz......
my 1999 apy s3 is only boosting 10psi all the time it dont pull anywhere like it used to and its doing my head in!!! although it dose boost to around a bar when in a high gear going up a hill!!!??
heres what iv checked:
falt codes= clear
maf been unpluged no change,
checked for leaks
had n75 j but changed it for the original f version.
turbo and wastegate fine
not been mapped..
anyone any ideas????????
cheers
if this helps it goes to exactly 10psi in each gear every time under acceleration
 
i got a forge one on hter that i cleaned and checked for sucktion and everything ok
 
malcolm30029085 said:
maf been unpluged no change,
Click to expand...

ok, just noticed this part, when you unplug it, is there not a dip in power? Is that what you mean by no change? If so, then your MAF is ********, and a lot of the time, it won't show any fault codes, my APY certainly didn't show any, despite the lack of performance.
 
MAF disconected will feel slugish, and slow, therefore if there is no change then that's where the problem is likely to be.
 
10 psi is about right for non mapped.. I always thought!
 
10psi (depending how accurate your boost gauge is) sounds like actuator pressure... this is normally brought on by limp mode.

<tuffty/>
 
just changed maf for new one and erased all falt codes also bypased the n249 valve..... still oly 10psi.
the car drives fine the throttle response is fine there is just no boost!!! also still no codes
any ideas?
cheers
 
Your problem sounds like the same as mine, really annoying, no codes and tried a few new parts to no avail. My car is also very heavy on fuel.

Turn the ignition off and on and should get you out of limp mode if you are which I dont think you are.

I take it you have a boost gauge. When did you notice it not boosting or spking as high
 
Bearing in mind you've said you've checked for fault codes, I assume you have access to VAG COM?

If this is the case, then I would go out and log block 115 to see requested vs actual boost.

This could be a lot of things, but you've checked all the obvious ones.

The reason you should check R vs A is because the MAP sensor could be misreporting and telling the ECU that there is more pressure than you are getting.
 
audi upgrades
yes mine runs very ritch too you can smell it!! i dont really remember exactly when it started but i do remember some days it wouldbe fine and others it would be sluggish. but now its all the time. i have a new map senser to put on will try that can that control boost???
what really confuses me is that it goes to exactly 10psi every time you boot it and stops dead, there is no fluxtuation at all as if something is regulating it.
dont have vag com but have acsses to a couple of snap on scanners
 
that sounds exactly like my problem. I had another look over my hoses for splits but could find any.

Let us know what happens when you change the Map sensor
 
Unplug the N75 electrically... if you run less boost then the N75 would appear to be working as is the actuator as you will be runnig on actuator pressure... if it doesn't change then it could indicate the N75 is faulty somehow...

Tricky one to make a useful suggestion without seeing the car tbh...

Have you checked everywhere for leaks etc? Assuming you have VAGCOM then maybe some logging is in order to see what is happening to rule out a few things...

<tuffty/>
 
audi upgrades
Logging in VAGCOM is the next step I would take... I would want to see what the ECU is seeing to try and work out what to do next... replacing individual sensors based on assumption gets expensive and testing them is not usually conclusive...

Your are making 10psi for only a few reasons.... If the MAP sensor was faulty then I would expect to see a boost deviation fault thrown as the difference between the request and actual would be too large. As you aren't seeing any faults then I would log the car in VAGCOM to see whats going on and take it from there.

You say you have checked for leaks but how thorough were you? Is it possible that the pipe to your boost gauge (assuming this i how you know you have 10psi) isn't comprimised anyway? I had something similar as I tee'd off the FPR and the FPR pipe had split meaning the my boost gauge was under reading and I lost power as the FPR wasn't adjusting fuel correctly.

Have you disconnected the N75 electrically yet? I would expect your boost to be around 7/8psi with that disconnected...

The other thing I have seen is an incorrectly fitted DV where someone had done an N249 bypass and put a one way valve in the vac line going to the DV... essentially meant the DV was permanently open causing a massive boost leak and didn't appear to throw a fault code either..

First blocks to log are 020 (timing pull), 031 (fuelling request vs actual) and 115 (boost request vs actual) in the engine group... engine temp at 90 degrees, third gear from 2k rpm to as close to redline as you legally can. After the logging run and before you turn off the engine, go to block 032 and note down the 2 values in the first 2 fields... these are your ECU adaption values..

Post up the results and we can take it from there...

<tuffty/>
 
have a log of 118 also so n75 duty cycle is shown

you can also run a diagnostic to activate n75 (amongst others) and listen and check it goes click click etc
logs first tho
 
I unplugged my N75 the other day and was running actuator pressure, about 6 psi.

What things would you suggest why an engine would be running lean and what values would you class as good when you look at block 32 after a logging run.
 
Engine shouldn't run lean unless really in trouble... ECU can compensate which is where block 032 comes in... values on both idle (first box) and part throttle (second box) should be close to 0% but anything up to +/- 5% is typical... anything above these values is indicative of a problem... positive values indicated the ECU is adding fuel and removing it for negative values... positive values indicate potential issues with air leaks...

Adaption can be +/- 25% beyond which a fault will be thrown...

<tuffty/>
 
Oh I see now. I have got logs for block 32 but they are when I have done a run, not after a run. Is it best to do it after a run to get more accurate adaption values. I have 0.4 for idle and -4.7 to -7 on part throttle. What does that show.

In block 31 my lambda is requestin 0.953 throughout the whole of the rev range and my lambda is doing roughly that but doesnt that value give you a lean AFR.
 
ok thanks for everyones help i will try and get some vag com readings and post them on here cheers
 
I have very similar problem with my 1999 1.8T sport, boost gauge will not go over 3.5psi no matter what i try. Same thing some days it was ok, some days boost was up and down when it felt like it, but now it is permanently maxing out at 3.5psi.
Replaced the MAF sensor no change, if unplugged the boost is restricted but runs fine.
Have VAG com but not dared to plug it in yet.
 
I un-plugged my N75, and there was no drop, or gain in boost! Does that mean it is faulty?
 
mark_sarah said:
I un-plugged my N75, and there was no drop, or gain in boost! Does that mean it is faulty?
Click to expand...

I would brave using VAGCOM and check for fault codes first.... Doesn't always mean the N75 is at fault as the N75 is used by the ECU to control boost... if the ECU detects a prob elsewhere, the ECU would not use the N75 at all and leave in in natural bypass state where the actuator would open at a preset pressure (about 0.5bar). When the ECU uses the N75 to control boost it does so by preventing boost pressure from getting to the actuator (thus keeping the wastegate closed) until it needs to control boost then pulses to allow the actuator to operate the wastegate controlling the boost pressure...

Get it plugged in and read the fault codes... you can't do damage that way :)

<tuffty/>
 
I unplugged mine the other day and my guage was showing a max of about 5 psi. Was so slow it was really funny. Have you checked the fuse for it.
 
Tried my mates N75 last night, not the problem.

FUSE!
Is there a fuse that controls the boost in some way? If so would it be one of the fuses on the drivers side fuse panel.
 
Malcolm, I just put a yellow spring in my 007p as I had a thought my green one was getting weak , even on my standard boost pressure and my gauge has started spiking again and holding few psi more.

Only had a little drive so I will see how it goes but its still sounds like its overfueling sometimes when taking off.

Worth a try though as my car is boosting better atm
 
Plugged Vag com in, got a few faults. 01371 and 01370. :idea:

Anyone help me with identifying what they mean? :readit:
 
How do i delete/reset faults? As i know the alarm faults are old faults.
 
S3 Nattie said:
Malcolm, I just put a yellow spring in my 007p as I had a thought my green one was getting weak , even on my standard boost pressure and my gauge has started spiking again and holding few psi more.

Only had a little drive so I will see how it goes but its still sounds like its overfueling sometimes when taking off.

Worth a try though as my car is boosting better atm
Click to expand...

i dont think it is my dv because i put a a ome one in just to check and its the same!!

weiredly it will boost to about 14 psi when going up hill?????

ummmmm?????
 
OK. Sounds similar to a problem I had a while ago on an identical engine.

Change the MAF. Unplugging it doesn't really tell that much. No fault codes for the MAF doesn't mean much either.

Can you swap out a MAF with another working model? Or get one from a breakers just to test with?

MAFs can 'misreport' meaning that they do send a signal but the values are wrong. This in turn means that the ECU doesn't produce a fault code for the MAF as it is working to a degree, it assumes that it's fine.
 
Got a brand new maf on there mate. Just realised aswell that when acceleratiing normaly and holding half throttle the boost drops off and dosent hold unless u put ur foot right down then it will hold 10psi exactly without spikeing. ????
 
Got a brand new maf on there mate. Just realised aswell that when acceleratiing normaly and holding half throttle the boost drops off and dosent hold unless u put ur foot right down then it will hold 10psi exactly without spikeing. ????
 
You must log in or register to reply here.

Similar threads

B
S3 only boosting to 10 PSI
Replies
28
Views
6K
Aidansmith_Newzealand
Aidansmith_Newzealand
S
Can’t boost over 10 psi
Replies
1
Views
500
NHN
NHN
R
S3 only boosting to 5 psi
Replies
20
Views
3K
<tuffty/>
<tuffty/>
AGB-S3
Max boost showing 9.5 > 10 Psi Normal ?
Replies
3
Views
589
AGB-S3
AGB-S3
JonnyDerv
K418t psi
Replies
3
Views
866
JonnyDerv
JonnyDerv
Top
Back