swapped 20g to hx35 now problem! Calling all wisemen!

[fastfive0]

This is for a friend of mine who has a 91 AWD tsi. Car was running fine with a 20g and we swapped over a holset hx35 that was running on his other talon. Now the car will accelerate fine until around full boost (17-20ish). When he reaches this boost usually around 4-5,000rpm the car will just lose all the power as if he shifted. The blowoff valve will go off too. All this happends while he still has the gas pedal floored!!What could cause the blowoff valve to prematurely go off? We thought bad tps,or coil so we swapped them and nothing. Checked the CAS and thats working properly. Did a boost leak test and all we found was a leak at the throttle body shaft which should not affect the car like this. We changed out computers and changed out his GM MAFT for a stock one and still no help. This setup ran fine on his other car. What are we doing wrong?

 

[wancsta]

I was gonna make another post but the first one I made sat unanswered for a week so I had the mods delete it. I guess I'll add some info and a short log of the event.

Once I go wot and hit full boost I will get what feels like fuel cut and will have nothing until I completly let off the throttle. I can keep it in it's well... state of nothingness by not letting off the throttle completly for as long as I want to and while I do this the afr's will hover between 11-12.5 so I believe it is still firing something. I have tried this set between 15-23 psi it always happens at wot at full boost not rpm dependant. Here is a list of things I've done/swapped.

2 cas's2
2 power transistors
3coilpack
2ecu's
2 keydiver chip's
stock chip
bpr7es's @.028 & .022
br8es's @.028 & .020
new wires
tps sensor
isc motor
injectors
knock sensor
cleaned/checked all grounds
fixed ALL boost leaks except a minor one @tb shaft seal
no cel's
all sensors in range
timing @5*btdc
cam timing dead on
and tried a few oddball theories I had in hopes

There's probably more I'm forgetting. I am at my wit's end on this one the only thing I have'nt replaced is the gm mas but it seems to be working fine. Driveability is not affected at all by this otherwise. Any new ideas are welcome please I'm out of them!

<iframe width="500" height="400" frameborder="0" scrolling="no" src="http://sheet.zoho.com/publish/wancsta/2009-05-21-19-59-11-1"> </iframe>

 

[knochgoon24]

Maybe the BOV just bit the dust and can't hold the pressure. Have you checked that line for holes?
What does the knock look like? Is it getting out of control?

 

[rush2252]

It sounds like fuel cut like you said... Do you have any logs you can post up? There was something at the bottom of your post but it was a dead link


Kolby

 

[wancsta]

The site is down for service right now. If you want pm your email to me and cant send the log to you. I forgot to add to list I swapped out 2 other known working bov's.

 

[rush2252]

What is the "I" column in your logs and TIMA? and are you running the 1g injector harness? Those things are prone for bad vibrations and getting inconsistent signal. Also your MAF appears to be reading some interesting numbers in relation to the TPS signal at around 99% indicating your at WOT between logs 58 thru 67. It looks like either a bad MAF or a massive boost leak under WOT.


I dont think it will matter but the TPS should be set at 10% on 1gs.


Kolby

One more thought have you inspected the WGA and flapper? Even though your boost gauge is showing 15-23psi you could have a leak if the flapper isnt seating ????

 

[fastfive0]

What is the "I" column in your logs and TIMA? and are you running the 1g injector harness? Those things are prone for bad vibrations and getting inconsistent signal. Also your MAF appears to be reading some interesting numbers in relation to the TPS signal at around 99% indicating your at WOT between logs 58 thru 67. It looks like either a bad MAF or a massive boost leak under WOT.


I dont think it will matter but the TPS should be set at 10% on 1gs.


Kolby

One more thought have you inspected the WGA and flapper? Even though your boost gauge is showing 15-23psi you could have a leak if the flapper isnt seating ????

I say WG and Flapper are screwed but he doesnt listen to me

 

[wancsta]

What is the "I" column in your logs and TIMA? and are you running the 1g injector harness? Those things are prone for bad vibrations and getting inconsistent signal. Also your MAF appears to be reading some interesting numbers in relation to the TPS signal at around 99% indicating your at WOT between logs 58 thru 67. It looks like either a bad MAF or a massive boost leak under WOT.


I dont think it will matter but the TPS should be set at 10% on 1gs.


Kolby

One more thought have you inspected the WGA and flapper? Even though your boost gauge is showing 15-23psi you could have a leak if the flapper isnt seating ????

The I column is IDC's. I know for sure I have an exhaust leak at the flapper but I don't see how it could possibly be related. I't still works just fine I can set the boost where I want it and it will hold rock steady when I said 15-23psi I meant I turned it down with the same results. If someone could tell me how this would cause anything other than an exhaust leak and slower spool I would have no problem pulling the turbo and fiddling with it.

 

[Ceddy]

Looks like a massive boost leak to me.

You airflow is dropping from 1000 down to 100 while you still have the gas floored.
Logging Boost and AFR would help if you can log them.

Do a boost leak test.
If your BOV is blowing open, the air will run backwards kinda and make you GM Maf run screwy.

You could hook your DSM Maf back up to see if it is a Translator or GM Sensor problem.


Boost leak test to +5 psi above boost you are running will most likely show you your problem.

 

[rush2252]

The I column is IDC's. I know for sure I have an exhaust leak at the flapper but I don't see how it could possibly be related. I't still works just fine I can set the boost where I want it and it will hold rock steady when I said 15-23psi I meant I turned it down with the same results. If someone could tell me how this would cause anything other than an exhaust leak and slower spool I would have no problem pulling the turbo and fiddling with it.

The only reason I mention this is because I had a similar situation with a 16g swap. I bought a used 14b complete and swapped a 16g centersection. It was acting very similar. I could get to 16psi w out any issues rock steady but then it would just run out of life. I couldnt figure it out. I dropped the exhaust from the o2 housing and noticed it sounded a little odd. I pull the o2 housing and the entire hotside had cracked through the flapper. It had almost identical issues. I dont have any logs of it as I only drove it a few pulls this way. But that sounds like it. If you turning up the boost to 23 or whatever maybe you loosing more boost pressure than what you think.


Kolby

If your actually leaking exhaust around the flapper and you know it fix it. I bet this will solve your headache. With the flapper not seating its most likely maxing out the turbine output due to the excessive leak remember how a turbo works think basics you have to have engine load and boost pressure. If there is any leak in the system your losing power

 

[wancsta]

I've done several blt's most reecently yesterday at 25+psi I have the boost set at 13psi right now today I swapped in a 2g mas with no change and I also tried another known working gm maf with no results. I also fixed the leak from the flapper and nothing. I am out of idea's so if there are any other ideas please put them out there!

 

[rush2252]

You overthinking the BLT. A leak on the flapper may not show up on a BLT depending on how your performing it. Are you running air through the compressor or through the intake? Like I said I didnt discover mine until I drove it and acted very similar to yours. It held 20psi fairly steady on the BLT but it didnt feel right. Does the turbo spool fairly quickly or does it seem to lag?

Kolby

If your MAF is reading X amount of air and your pushing 23psi you could be hitting fuel cut. You losing boost through the flapper and still dumping fuel read by the MAF. Just an idea

 

[dsmfa9nutter]

Silly question but is your wastegate actuator connected to the flapper?

 

[Ceddy]

If your MAF is reading X amount of air and your pushing 23psi you could be hitting fuel cut. You losing boost through the flapper and still dumping fuel read by the MAF. Just an idea

If he is running a KeyDiver chip, FuelCut or AirFlow Cap won't be a problem.

 

[rush2252]

The BOV releasing has me scratching my head. It should only go off once you let off and get out of boost into hg WTF

The OP states your losing power at WOT and the BOV is releasing....

Just a question but how do you have the MBC source and the BOV source?
I cant think of anything but the more info the more ideas...


Kolby

 

[wancsta]

The BOV releasing has me scratching my head. It should only go off once you let off and get out of boost into hg WTF

The OP states your losing power at WOT and the BOV is releasing....

Just a question but how do you have the MBC source and the BOV source?
I cant think of anything but the more info the more ideas...


Kolby

I don't actually think the BOV is opening on it's own it only seem's like it because of the sound the turbo make's spooling down I believe. I't kind of sounds like the sound you get when you hit bankrupt on wheel of fortune . The BOV source is from the stock location on the intake manifold with nothing tee'd in to it and the mbc is right off the compressor housing.

If he is running a KeyDiver chip, FuelCut or AirFlow Cap won't be a problem.

Thankyou yes I am running a keydiver stage 3.

Silly question but is your wastegate actuator connected to the flapper?

Yes it's connected it's an atmospheric dump o2 housing if it came off I'de know real fast. I't was a little laggier than it shoud be but since I fixed the exhaust leak at the flapper I'ts about where it should be now spooling too fast!

Here is a video I included in my original post how much it will help I don't know. Keep in mind each little pull I make it is'nt me letting off the gas.

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/Rdn1nlt0fz4&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/Rdn1nlt0fz4&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

 

[92awddsm]

I know it sounds strange but I would pull the uicp between the ic and gm maf and check for a leaf, part of a rag, etc floating around.

 

[wancsta]

I just had the uicp apart and disected two days ago and swapped the maf yesterday I would have LOVED to find something in there.

 

[rush2252]

its definately mechanical. Have you bench tested the WGA? I hear the BOV releasing everytime you lose boost you said the BOV definately held 25+ on the BLT?? It acts as if the throttle plate is closing and your going into HG.

Kolby

Just a thought but how is the spring and diaphram on the external WG?

Ive watched the video and it really has to be the BOV not holding pressure. Or you have something blocking the line from the intake mani to the BOV. If its restricted in any way this could cause the early release

 

[wancsta]

its definately mechanical. Have you bench tested the WGA? I hear the BOV releasing everytime you lose boost you said the BOV definately held 25+ on the BLT?? It acts as if the throttle plate is closing and your going into HG.

Kolby

Just a thought but how is the spring and diaphram on the external WG?

Ive watched the video and it really has to be the BOV not holding pressure. Or you have something blocking the line from the intake mani to the BOV. If its restricted in any way this could cause the early release

The turbo is internally gated with an atmosperic dump and the bov does hold whatever I have thrown at it during blt's. I will however check the line today but that is also brand new high pressure fuel grade line.

What I am really trying to figure out is how I can only be getting 100hz at wot when just a blip on the throttle will show even more than that. I am certain if I can figure out what is causing that all my problems will be solved. Even if say the bov where opening early I would still be able to accelerate under na power since the maf is in blow-thru configuration instead there is nothing until I get completly off the gas and then it will go back to normal operation.

 

[wancsta]

Well quick update after a month of hundres of man hours and no progress whatsoever I have decided to convert to load based tuning via ds-map/jackal . This may not be the smartest decision I have ever made but I am willing to try anything at this point. I'm hoping this can at least clear up a few things for me. I went ahead and ordered the ostrich 2.0 , gm ait, map sensor and adapter harness today. I am going to try to have it installed and running this weekend I will keep you guys posted with the results. Thanks thusfar for the input.

 

[T9S1i]

i would swap your TB out... i think its not holding open

 

[91-gsx]

Do you have the keydriver chip made with a stutterbox setting? If so, does it seem to release the bov around the rpm of the stutterbox setting that you asked for? If these 2 things apply then you have the clutch switch the wrong way around. I'm only asking these series of questions because this was the cause of a problem I had that was similar a while back. You already said that all you changed was the turbo related things. I just want to cover all bases just in case. Good luck with the problem, the guys on here will surely find it with you.

 

[wancsta]

Do you have the keydriver chip made with a stutterbox setting? If so, does it seem to release the bov around the rpm of the stutterbox setting that you asked for? If these 2 things apply then you have the clutch switch the wrong way around. I'm only asking these series of questions because this was the cause of a problem I had that was similar a while back. You already said that all you changed was the turbo related things. I just want to cover all bases just in case. Good luck with the problem, the guys on here will surely find it with you.

The clutch switch is hooked up right I already went through that deal when I first installed it.

 

[rush2252]

So I have one more idea. Any chance you installed the GM MAF backwards? It will only function right if its facing the correct way. Im sure you know this but thought Id throw some more ideas out there.


Good Luck
Kolby