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Can't hold boost after W/M installtion. Help?

G

GIACUser

Master Wallet Mechanic
RGTI13 said:
Hey everyone, I apologize in advance for the long post.

Before W/M Installation:

CTS turbo kit, CTS relocate, Rev.D DV.
Held 24/25 PSI, tapered off to 21/22... normal for Eurodyne.

After W/M Installation:
Held 24/25, tapered to 21/22.... and then it got worse.
I slowly found myself peaking at 21 PSI, and tapering off to 15/16 PSI.

Why?!

What did we do?

1. Switched the DV to a used Rev.D DV (we have a new one coming tomorrow).
2. Switched the DV housing to a new CTS DV housing and seated it properly.

After this, we found the car was holding 25 PSI all the way through redline!!!

3. Added the Manual Boost Controller, cranked it up to 27/28.

Car held 27 PSI all the way through redline!!!

This is where the oddities start.

We then came back to the shop, grabbed the computer and started logging and adding timing because we were getting zero correction at 27/28 PSI.

Did a few pulls... one was 25 PSI, one was 17 PSI, one was 19 PSI... WTF?!

Now it seems to have settled again on 21 PSI spikes and tapering off to 17 PSI.......

What could possibly cause this? Any ideas are helpful.
Click to expand...

Not sure how your water meth is setup but here is a possibility. WM line could have come off - instead of a wm injection you are spraying to atmosphere and have a boost leak. Don't ask me how I know this can happen. If you have push to fit type fitting they have to be cut square and pushed on with some force. Just something to check since you said it occurred since WM install.

I have also seen push to fit leak badly but still be connected mostly because line was not cut square.

Or less likely - you put in a check valve backwards - this did not happen to me but anything is possible. Checkvalve from Snow has about 16psi cracking pressure, DO is about 10psi so if you put them in backwards you could be blowing bubbles into the alky tank. Again not likely but stranger things have happened.
 
V

vwgti2.0t

Go Kart Champion
I would bet you have an n75 problem. Probably broke one of the ports off during installation, or do you have a fail safe wired in for your W/M to the N75? If it's at 98% duty cycle and you aren't getting full boost you have a leak. I would bet money on it's at or around the n75 valve.
 
C

Cryptic19111

Go Kart Champion
^Yep, was just going to post this.. 98% n75 duty cycle means its keeping the wastegate closed to build boost, which it can't.
 
R

RGTI13

Go Kart Champion
No failsafe in N75.... maybe bad N75, but I believe that would cause ZERO boost, starting issues, and CELs/Limp mode.... I have none of that.

Tomorrow I will bring that up to my shop and see what they think. I just want to get this manual boost controller off ASAP and throw on the GFB DV+. I STILL think my restrictive stock piping + modshack intake could be causing the restriction at high RPMs... but who knows.

I don't think it's anything mechanical. We are getting zero timing pull, even when we logged at 27 PSI... no knocking, no weird noises. No whistling, so it's probably not the crankcase vent... trust me I've read everything. It doesn't make any sense. Could it be turbine related? I don't know.
 
R

RGTI13

Go Kart Champion
UPDATE:

Did a little checking tonight since the roads are empty...

During half throttle, I can EASILY peg 30 PSI and hold. It bounces between 30 and 28... no problem.

Before the car was fully warmed up, I was able to peg 27 PSI under full throttle it seemed.

Once it was warmed up, It was back down to 22, holding 18/19 under FULL throttle.... Half throttle I could still peg and hold 28-30 PSI no problem.

Also... unplugged my MAF sensor, car runs fine, no codes either. Is that normal?

Thanks again!
 
V

vwgti2.0t

Go Kart Champion
Wait, you have a MBC? How is that plumbed in? That's your issue... I ran a MBC for a little while and had it set to 27psi or so. It would work for a while and after driving the car for a while it would back boost off as well. The ECU was just seeing something it didn't like and backing boost off. Took it out and everything was back to normal.

Work of reference, dont use the MBC with the DV+. That was the final straw for me. The car didn't like that at all. I might have missed it, but is this a K04?

Either way, get the MBC out and it should be back to normal.
 
R

RGTI13

Go Kart Champion
*****2.0t said:
Wait, you have a MBC? How is that plumbed in? That's your issue... I ran a MBC for a little while and had it set to 27psi or so. It would work for a while and after driving the car for a while it would back boost off as well. The ECU was just seeing something it didn't like and backing boost off. Took it out and everything was back to normal.

Work of reference, dont use the MBC with the DV+. That was the final straw for me. The car didn't like that at all. I might have missed it, but is this a K04?

Either way, get the MBC out and it should be back to normal.
Click to expand...

That's what I'll be doing this week. My shop ASSURES me that its wired in correctly. It must be half correct because I can definitely limit boost with it(10psi). He has 10+ cars running the identical MBC wired the same way all boosting 28 - 32 psi. My car seems to be the only one that just doesn't want to make the boost. It worries me that its a turbine problem.
 
Sauce118

Sauce118

Ready to race!
RGTI13 said:
Hey everyone, I apologize in advance for the long post.

Before W/M Installation:

CTS turbo kit, CTS relocate, Rev.D DV.
Held 24/25 PSI, tapered off to 21/22... normal for Eurodyne.

After W/M Installation:
Held 24/25, tapered to 21/22.... and then it got worse.
I slowly found myself peaking at 21 PSI, and tapering off to 15/16 PSI.

Why?!

What did we do?

1. Switched the DV to a used Rev.D DV (we have a new one coming tomorrow).
2. Switched the DV housing to a new CTS DV housing and seated it properly.

After this, we found the car was holding 25 PSI all the way through redline!!!

3. Added the Manual Boost Controller, cranked it up to 27/28.

Car held 27 PSI all the way through redline!!!

This is where the oddities start.

We then came back to the shop, grabbed the computer and started logging and adding timing because we were getting zero correction at 27/28 PSI.

Did a few pulls... one was 25 PSI, one was 17 PSI, one was 19 PSI... WTF?!

Now it seems to have settled again on 21 PSI spikes and tapering off to 17 PSI.......

What could possibly cause this? Any ideas are helpful.
Click to expand...

I know I'm reviving an old thread but I'm having the same problem after k04 install. No boost leaks. Possible maf or map. But what ended up fixing your problem? I don't run a MBC either.
 
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