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2006 RX8
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423 Posts
Discussion Starter #1
Damn boost creep!! I had recently installed my Bosal shorty DP (catless), and a catless up-pipe. Kept the third cat, and am running a FAT rear exhaust. Anyway I had purposely avoided the Bosal 3rd cat delete because of boost creep concerns, but obviously the shorty DP is all thats needed to create enough flow increase to cause overboost...even with the tiny stock turbo!

I had noted that the boost levels were slightly higher than they had been, and I expected this to be the case. Roll-ons are another issue though. I know the VF39 doesn't like catless Dp's exhaust systems, but didn't think the stock TD35 would be affected. Anyway a downshift to fourth and hard acceleration ended in me seeing around 1.2-1.3 KgCm2, followed by boost cut and a CEL. Ouch... .

I am also going to disconnect the wastegate actuator arm and check the wastegate flapper for interference with the Bosal divorced DP divider plate. Never can tell and I know this has been an issue in the past.
 

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Recovering Modaholic
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welcome to the club :( mine does it consistently in 5th gear at WOT about 4500 RPM's. I can go to redline at WOT in all the other gears with no problem. I've only done it 2 or 3 times because getting that CEL and actually feeling the boost cut makes my heart drop! I know its bad for the motor, I'm just glad it happens at very high speeds and at an RPM I rarely see in 5th gear.

I think wastegate porting is the only solution other than a custom tune.
 

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If it's real boost creep then tuning won't help. I'm surprised the stock turbo is getting creep geez. Did you guys pull the code? P0244?
 

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2006 RX8
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Discussion Starter #4
ZuMBLe said:
If it's real boost creep then tuning won't help. I'm surprised the stock turbo is getting creep geez. Did you guys pull the code? P0244?
No I didn't pull the code, because I don't currently have a tool to do it with. I do have the sofware, just not the cable/connector Anyone know of a good resource?). I do know this though, I was running in 5th at about 60-65 and dropped into 4th to pass a truck. I remember seeing the boost needle swing way-up and then the engine stalled and it threw a CEL. I know it wasn't the rev-limiter, and wish I had my old defi gauges with peak-hold so I could see exaclty what I did hit boost-wise.

I agree that this seems odd for the stock turbo. Maybe the wastegate flapper is getting hung though. If this is happening the wastegate wouldn't open all the way, and perhaps keep the pressure building. Just a theory, but for now I am being careful until I can check it out closer.

My wife and boys were with me, and I blamed the 91 octane gas here in NM. Told her the best fix was a new 91 octane MAP using a device called the Access Port. Well who knows it could be part of the problem, along with that tiny turbo!!
 

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When I was getting dyno tuned there was a legacy there that got it's wastegate flapper stuck open on a divorced wastegate setup. The tuner said wastegates get stuck all the time on the divorced setups. So it's quite possible that your wastegate is stuck but closed. I never passed 16 psi when running my TD04 with STi IC and stage 2 with highflow cat. I think with suck EM you need 17.5 psi for a short amount of time before the CEL will go off.

AP probably won't solve your overboost problem but at least you can read the CEL and run a new map.. ;) Maybe someone in your area with a AP cable can let you borrow it or you can buy one from Cobb. You can tell them you broke your cable and they will sell you one cheap I think.



N10S said:
No I didn't pull the code, because I don't currently have a tool to do it with. I do have the sofware, just not the cable/connector Anyone know of a good resource?). I do know this though, I was running in 5th at about 60-65 and dropped into 4th to pass a truck. I remember seeing the boost needle swing way-up and then the engine stalled and it threw a CEL. I know it wasn't the rev-limiter, and wish I had my old defi gauges with peak-hold so I could see exaclty what I did hit boost-wise.

I agree that this seems odd for the stock turbo. Maybe the wastegate flapper is getting hung though. If this is happening the wastegate wouldn't open all the way, and perhaps keep the pressure building. Just a theory, but for now I am being careful until I can check it out closer.

My wife and boys were with me, and I blamed the 91 octane gas here in NM. Told her the best fix was a new 91 octane MAP using a device called the Access Port. Well who knows it could be part of the problem, along with that tiny turbo!!
 

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Recovering Modaholic
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I need to pull the code, the CEL reset itself after a few re-starts. I'm pretty sure its the catless DP's that cause the CEL/creep
 

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2006 RX8
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Discussion Starter #7
ZuMBLe said:
When I was getting dyno tuned there was a legacy there that got it's wastegate flapper stuck open on a divorced wastegate setup. The tuner said wastegates get stuck all the time on the divorced setups. So it's quite possible that your wastegate is stuck but closed. I never passed 16 psi when running my TD04 with STi IC and stage 2 with highflow cat. I think with suck EM you need 17.5 psi for a short amount of time before the CEL will go off.

AP probably won't solve your overboost problem but at least you can read the CEL and run a new map.. ;) Maybe someone in your area with a AP cable can let you borrow it or you can buy one from Cobb. You can tell them you broke your cable and they will sell you one cheap I think.

Yeah...I know the AP isn't going to solve the overboost problem....simply getting the wife ready for an AP purchase! I am somewhat concerned about the divorced set-up hanging, but in the near future, I will slightly warm car, then disconnect the actuator arm and see if the flapper swings freely. Not sure if the AP cable is what I need or not. Previously it was a 9 pin to OBD connector cable. I am sure someone sell them, just not sure who...need to dig around a bit.

As noted it is most likely to simply be the catless DP.I will provide an update later once I have checked the divorced DP interference.

Thanks

Jeff
 

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The AP cable will work with the Tari Racing logging software. I use it all the time. So, if you get a AP, you get more performance, the ability to read and reset CEL, the possibility of getting custom maps AND logging. ;)

N10S said:
Yeah...I know the AP isn't going to solve the overboost problem....simply getting the wife ready for an AP purchase! I am somewhat concerned about the divorced set-up hanging, but in the near future, I will slightly warm car, then disconnect the actuator arm and see if the flapper swings freely. Not sure if the AP cable is what I need or not. Previously it was a 9 pin to OBD connector cable. I am sure someone sell them, just not sure who...need to dig around a bit.

As noted it is most likely to simply be the catless DP.I will provide an update later once I have checked the divorced DP interference.

Thanks

Jeff
 

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Premium Member
2012 GTI DSG 6-speed
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N10S said:
I am also going to disconnect the wastegate actuator arm and check the wastegate flapper for interference with the Bosal divorced DP divider plate. Never can tell and I know this has been an issue in the past.
The newer Stromung DWG downpipes do not have the divider plate in there anymore. I have not had any issues with it and my setup is similar- 3rd cat with Cobb catback.
 

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Fear the Gorilla!
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181 Posts
I had my Vf39 ported and polished by DAVENOW on NASIOC. I have yet to hit boost cut or creep with teen high altitude temps in PA and in the mountains...I highly recommend you guys look him up. Tell him GTP with the FXT sent you.
 

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2006 RX8
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Discussion Starter #11
GTP said:
I had my Vf39 ported and polished by DAVENOW on NASIOC. I have yet to hit boost cut or creep with teen high altitude temps in PA and in the mountains...I highly recommend you guys look him up. Tell him GTP with the FXT sent you.
Did your Vf39 have any cracks in it? I had heard that Deadbolt won't port and polish a VF39 with a crack, and as an owner of a VF39 with slight crack, just wondered if DAVENOW would take the project on regardless?

Thanks for the lead and the info on the performance of the polished and ported Vf39!

Jeff
 

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Fear the Gorilla!
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181 Posts
N10S said:
Did your Vf39 have any cracks in it? I had heard that Deadbolt won't port and polish a VF39 with a crack, and as an owner of a VF39 with slight crack, just wondered if DAVENOW would take the project on regardless?

Thanks for the lead and the info on the performance of the polished and ported Vf39!

Jeff

He may do it. Mine wasn't cracked when I sent it. And even though its cracked I bet he'll do it anyways. $100 shipped.
 

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2006 RX8
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Discussion Starter #13
I just received my Vf39 last week and to be honest, I can hardly see a crack at all. Anyway, I will contact Davenow in the near future!

Thanks again!

Jeff
 
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