Boost issues
03-19-2009, 12:48 AM
#1
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Boost issues
Hello all,
I've been running my TT kit for about a week now and finally got a TurboXS HP Manual Boost Controller. I believe I have it set at about 5 psi, but I'm still having issues.
The main reason why I got the MBC was to get rid of the nasty boost spike & hold that was happening at about 5k rpm to redline (there is a 4 psi spring in the TiAL 38mm wastegate, but the boost would spike to almost 10 psi during the last 1250 rpms).
The spike is still there after installing the MBC according to the instructions that came with it (horizontal connection coming from positive pressure source, vertical connection going to wastegate).
The line that is connected to the horizontal connection comes from the furthest left hose from the vacuum block that is still vertical, the middle hose goes to the Bosch BPV, and the small hose on the right goes to the boost gauge.
My other issue is that when in 4th gear around 3.5k rpm, if I punch it, the AFRs go to 10.0 and then the car starts to hesitate about every half-second to full second until the RPMs get to about 4.5k and then it smooths out.
Any ideas? I was planning on going to the track Friday, but unless I can get the boost and hesitation situations sorted out, I'm not going to...
Thanks in advance!
Josh
I've been running my TT kit for about a week now and finally got a TurboXS HP Manual Boost Controller. I believe I have it set at about 5 psi, but I'm still having issues.
The main reason why I got the MBC was to get rid of the nasty boost spike & hold that was happening at about 5k rpm to redline (there is a 4 psi spring in the TiAL 38mm wastegate, but the boost would spike to almost 10 psi during the last 1250 rpms).
The spike is still there after installing the MBC according to the instructions that came with it (horizontal connection coming from positive pressure source, vertical connection going to wastegate).
The line that is connected to the horizontal connection comes from the furthest left hose from the vacuum block that is still vertical, the middle hose goes to the Bosch BPV, and the small hose on the right goes to the boost gauge.
My other issue is that when in 4th gear around 3.5k rpm, if I punch it, the AFRs go to 10.0 and then the car starts to hesitate about every half-second to full second until the RPMs get to about 4.5k and then it smooths out.
Any ideas? I was planning on going to the track Friday, but unless I can get the boost and hesitation situations sorted out, I'm not going to...
Thanks in advance!
Josh
03-19-2009, 01:02 AM
#2
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Nice write up explaining your problem.
As fas as your last comment about the car hesitating at certain rpms....... its just your tune. You need to get the car tuned so it runs smoothly and efficiently up through the whole rpm band. I wouldnt recommend going to the track before getting a professinal tune. Something could happen... you run lean and boom.... theres your motor.
As far as the boost spike..... check the tightness of the top housing of the WG..... the part that holds the spring down. It could be a crap sping for some reason too. You might wanna just spend 25$ and get a new spring to eliminate that. Make sure your boost signal going into the WG isnt supposed to be on the top port.
As fas as your last comment about the car hesitating at certain rpms....... its just your tune. You need to get the car tuned so it runs smoothly and efficiently up through the whole rpm band. I wouldnt recommend going to the track before getting a professinal tune. Something could happen... you run lean and boom.... theres your motor.
As far as the boost spike..... check the tightness of the top housing of the WG..... the part that holds the spring down. It could be a crap sping for some reason too. You might wanna just spend 25$ and get a new spring to eliminate that. Make sure your boost signal going into the WG isnt supposed to be on the top port.
03-19-2009, 01:09 AM
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Originally Posted by SoFloTC
are u using AEM FIC? if so that could cause the hesitating if you dont have the resistor mod.
Is it like a really hard jerk? Like it feels like its misfiring? Or does it just feel like its bogged down at those rpms?
03-19-2009, 01:15 AM
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I do have the F/IC and the Boomslang harness for the 07+ tC, so the resistors are already installed.
As for the tune, it was just tuned last Wednesday by UMS Tuning in Mesa, so its been on a dyno. The tune that's on the F/IC is good for about 6psi. The good thing that even when the boost spikes and holds at about 10 psi, its only for that short amount of time and the AFRs stay between 11.2 and 12.5 (but lately I have been shifting early to avoid that spike).
I will try to double check the wastegate housing tightness. And according to this guide from TiAL, i have the MBC sort-of right... FML (lol)
As for the tune, it was just tuned last Wednesday by UMS Tuning in Mesa, so its been on a dyno. The tune that's on the F/IC is good for about 6psi. The good thing that even when the boost spikes and holds at about 10 psi, its only for that short amount of time and the AFRs stay between 11.2 and 12.5 (but lately I have been shifting early to avoid that spike).
I will try to double check the wastegate housing tightness. And according to this guide from TiAL, i have the MBC sort-of right... FML (lol)
03-19-2009, 01:18 AM
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Originally Posted by kirk212
Yea, this is very true. I had to do it with mine.
Is it like a really hard jerk? Like it feels like its misfiring? Or does it just feel like its bogged down at those rpms?
Is it like a really hard jerk? Like it feels like its misfiring? Or does it just feel like its bogged down at those rpms?
03-19-2009, 02:51 AM
#9
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The spikes were happening before the boost controller were installed though. It looks like I might have it installed in the wrong place according to TiALs document here:
http://www.tialmedia.com/documents/w..._wginstall.pdf
http://www.tialmedia.com/documents/w..._wginstall.pdf
03-19-2009, 03:42 AM
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lol, I didn't even notice that. Yeah, WG Vent > Side of MBC then out the bottom to the vacuum block.
Just run the vacuum hose from the WG to the vacuum block. If it doesn't spike anymore, it's the MBC. If it still spikes, it's the WG.
Just run the vacuum hose from the WG to the vacuum block. If it doesn't spike anymore, it's the MBC. If it still spikes, it's the WG.
03-19-2009, 03:47 AM
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By WG vent do you mean the top connector? I think it might be the wastegate though. I don't have another one to test with though... Aen is going to let me borrow his once he's able to get to my part of the valley...
03-19-2009, 03:57 AM
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I was under the impression that if you run a Boost controller it should be more set for more psi then the spring you have in, not like just 1 or 2 lbs that might be a problme
im not 100 percent on that, just what ive herad down the line
im not 100 percent on that, just what ive herad down the line
03-19-2009, 03:59 AM
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The minimal setting on my MBC put me at 9.5PSI (6PSI WG spring). I always thought the minimal setting was supposed to be the WG spring pressure, then go up to, at most, double WG spring pressure.
03-19-2009, 04:00 AM
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Like I said before, the MBC was not installed last week after I got the car back from UMS. The boost spikes were happening then when it was just the wastegate.
I bought the MBC to take care of the spike & hold (which seems to be ineffective ATM)
I may just end up taking it to a shop and having them look at it...
I bought the MBC to take care of the spike & hold (which seems to be ineffective ATM)
I may just end up taking it to a shop and having them look at it...
03-19-2009, 04:03 AM
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BTW, bottom of WG goes to bottom of MBC and side of MBC goes to ur vacuum block. I have it tapped to the throttle body vacuum though, for better vacuum. And in the block I have the FIC, Boost Gauge & Blowoff Valve.
03-19-2009, 04:07 AM
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it seems that some of the stuttering is from the tune, but the spike has to be WG issue. Probably need a new spring or something. I believe Chris was having some kind of issue like that and might off gone away after taking it apart and looking at it. Look at his thread "TT Houston Style"
03-19-2009, 10:53 AM
#20
Originally Posted by Carlanga
it seems that some of the stuttering is from the tune, but the spike has to be WG issue. Probably need a new spring or something. I believe Chris was having some kind of issue like that and might off gone away after taking it apart and looking at it. Look at his thread "TT Houston Style"