Interesting troubleshooting on Bosal Downpipe
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Car Info: 96 Chevy Impala SS, 06 GMC 2500HD (former 02 WRX)
Interesting troubleshooting on Bosal Downpipe
OK, so in the "trickle-down" economics of used Subie parts we had Mexicanpizza buy ChrisW's Vishnu Turboback, and I bought the Bosal downpipe that came off of Mexicanpizza's car.
Installed it on Friday night, hoping to race at Sacramento on Sat night (BTW Justin, saw your WRB wagon there but never saw you). Fired the car up.....sounded GREAT.
Went for a drive.....no boost MOST of the time until 5000+ RPM. However ONCE in a while it would boost up normally. What the heck?!?!??
Since it was not working right, I didn't race the WRX but just rode along with the some friends in the Impala club (and we had one of THOSE cars break on the way to the track as well.....yep, between all that and the ****-poor track prep and HUGE lines at Sac Raceway this past Saturday pretty much sucked some hairy ones!).
Eric (Mexicanpizza) was kind enough to let me try his ECU this afternoon (AccessECU Stage2) in case it was the ECU flipping out at the new exhaust flow......no dice, problem still there.
So tonight I took the downpipe back out. And immediately found the problem....
The Bosal downpipe has a divider, which is on the turbo outlet to divide the turbine from wastegate gases. Picture of the downpipe at this link. What happened is that between production tolerances and the bracket to the tranny not being quite "right" for MY particular car, the divider was moved over a little. Just enough that it was BARELY touching the wastegate "flap" when it opened.....and causing the wastegate to USUALLY stick open (thus why it would work normally once in a while).
5 minutes with the die grinder and pliers to "clearance" the divider, and reinstalled the downpipe. When we reinstalled, we took care to make sure that the "slop" in the bolts was gonna move the downpipe divider away from the wastegate (i.e. never reattached the tranny bolt, since it doesn't line up now).
Net result : works great now! And the car definitely builds boost quicker
.
Need to get back out to Sac Raceway at least once before the third cat goes back in (to be legal again for STX next year in AutoX) just to see what it'll do
.
So if you have wierd problems with no boost until VERY high RPM, check to make sure the wastegate isn't sticking open.
Installed it on Friday night, hoping to race at Sacramento on Sat night (BTW Justin, saw your WRB wagon there but never saw you). Fired the car up.....sounded GREAT.
Went for a drive.....no boost MOST of the time until 5000+ RPM. However ONCE in a while it would boost up normally. What the heck?!?!??
Since it was not working right, I didn't race the WRX but just rode along with the some friends in the Impala club (and we had one of THOSE cars break on the way to the track as well.....yep, between all that and the ****-poor track prep and HUGE lines at Sac Raceway this past Saturday pretty much sucked some hairy ones!).
Eric (Mexicanpizza) was kind enough to let me try his ECU this afternoon (AccessECU Stage2) in case it was the ECU flipping out at the new exhaust flow......no dice, problem still there.
So tonight I took the downpipe back out. And immediately found the problem....
The Bosal downpipe has a divider, which is on the turbo outlet to divide the turbine from wastegate gases. Picture of the downpipe at this link. What happened is that between production tolerances and the bracket to the tranny not being quite "right" for MY particular car, the divider was moved over a little. Just enough that it was BARELY touching the wastegate "flap" when it opened.....and causing the wastegate to USUALLY stick open (thus why it would work normally once in a while).
5 minutes with the die grinder and pliers to "clearance" the divider, and reinstalled the downpipe. When we reinstalled, we took care to make sure that the "slop" in the bolts was gonna move the downpipe divider away from the wastegate (i.e. never reattached the tranny bolt, since it doesn't line up now).
Net result : works great now! And the car definitely builds boost quicker
.Need to get back out to Sac Raceway at least once before the third cat goes back in (to be legal again for STX next year in AutoX) just to see what it'll do
. So if you have wierd problems with no boost until VERY high RPM, check to make sure the wastegate isn't sticking open.
Chewwwwy
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i had the same problem with my MRT downpipe when i got it. the tab that seperates the wastegate/exaust housing was too long. when you tried to bolt it up, the divider would prevent you from doing so, and a 5mm gap between the dp and turbo resulted. same thing, 5 min with a diegrinder and all is well.
has anyone else had similar problems with any downpipes?
glad to see you got it taken care of Ed!
has anyone else had similar problems with any downpipes?
glad to see you got it taken care of Ed!
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I offer excellent technical support and guarantee's on all used products I sell! </sarcasm>
Glad it worked out Ed...if you need any other parts off my car let me know! 
Glad it worked out Ed...if you need any other parts off my car let me know!
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