Ok here's my Problem... A few months back I installed 272's,TBE with test pipe, 02
housing, hallman MBC, Hks RS intake and a walbro 255. I took it to Turbo trix to
get a custom dyno tune. Mark tuned the car into a beast. He set my boost I
believe to 22 psi. Now just this week I notice that the car wasn't feelin the same,
it felt slow !!! I felt like I wasn't getting full boost out of her. So I started to give it
WOT in all gears to see if I was hitting 22 psi of boost and guess what... I wasn't. I noticed that in 2nd gear I'm only hitting about 17 psi then it tapper's and stay's on 15psi. 3rd gear does the same. 4th gear it will hit about 19psi then tapper to 16psi. 5th it will hit 21psi then tapper to about 19psi. I know I must have a boost leak or some boost leaks somewhere, but I was wondering if it could be something else besides a boost leak. The car was boosting fine in all gears b4 this week. Can it be that my clutch is slipping ? And b4 u tell me to search I already did. I want some more input.

Thanks in advance.

 

u would notice ur rpms jump if it was ur clutch.

 

YOu wouldn't just randomly boost less in each gear if it were the clutch, but since you didn't give any details as to what happens when you hit peak boost in each gear, we can't make that diagnosis.

It could be a boost leak, but it's likely something else. There's really nothing that would randomly cause your boost to register a few psi lower other than it being hot as hell. Did you happen to get tuned at 22psi in the Winter or during cooler months? Our boost lower in the summer and rises in the winter due to the temperature (air density).

 

Perform a boost leak test to find any leaks. If you have no significant leaks, buy a boost controller and turn the boost back up to 22 psi.

 

Well i dont know how much more detail I can give. The problem is that I'm not hitting my peak boost of 22psi. In gears 1,2,3, I'm hitting 17psi at WOT then it drop's to 15psi and it stay's there till redline. 4th gear I'll hit 19psi then it will drop to 15psi and stay there til redline. In 5th gear I'll hit 20psi then it tapper's down to about 19psi and stay there til redline at WOT. B4 this week I would hit my peak boost of 22psi, then it would maybe tapper down to 21psi and stay there til redline at WOT in all gears. Can it be my wastegate going bad ?? I would just like to have an idea of what it could be if the problem isn't a boost leak.

 

Any wierd noises at all?

 

Well, you may want to know possibilities before doing a pressure test, but there is no one answer we can give you. You need to do the boost leak test BEFORE asking us to solve the problem, because there isn't anything in your description that sounds strange. What you've described is just how our boost operates. We see less peak boost in lower gears, because there is less load. After spiking, we drop down, hold, and then taper off at high rpm. There's nothing abnormal with your boost other than it being lower than before. Have you turned up the boost to see if it goes back to where it was? Do you know for sure it wasn't turned down by someone or something? There's several simple things you should do to troubleshoot before enlisting our help.

 

Well tomorrow I will be messing around with the car all day to hopefully find out if i have any boost leak's. I'll post up if I find any thing wrong besides a leak. Thanks warr.

 

did you ever find out why your boost was tapering? Leaks?

 

I just noticed the same problem. Last month I got a dynoflash custom tune for 21 psi and the car has been running strong. Within the past couple days I have noticed the car not feeling as fast. The only thing that has been done since the flash was an oil change.

I now read roughly 2-5psi lower peak then taper. One thing that I noticed however, is that when accelerating I can hear the turbo spool and the forge rs valve much more so then before. This leads me to believe I have a leak somewhere.

Any thoughts?

 

Yeah you have a huge leak.

 

BOV maybe leaking?

 

I plan on on checking everything when I get home from work today.

I am leaning toward a leak on the intake side due to the increased sound volume of spool up and the valve recirculating.