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Need help with overboost problem

1460 Views 2 Replies 2 Participants Last post by  darag2358
So, here's the summary: Speedtuning ECU installed Fall of last year on my 99 R. Just before I installed stylin' hoses for all the vacuum lines. When I put on the new ECU, power was great but felt sporadic. Got a boost gauge and saw that I was overboosting big time before dropping. Hitting 25psi without even going WOT (maybe 2/3 -3/4) which is not good obviously
. Just been keeping it out of heavy throttle and watching my gauge since then.

Now it's getting warmer and I want to get this fixed. Got in on the IPD TCV group buy thinking that could be the problem. Still same issue. So next logical thought is something is up with the wastegate. Wastegate and actuator test OK (made a tester with a guage).

I figure the actuator just isn't getting the pressure it needs to open. So I hooked a second pressure gauge on the wastegate actuator line to see what that line was doing when I was boosting. I found the pressure on the actuator line is often very delayed. I made a video clip of it (when I see boost climbing in to the 20's I immediately let off gas). The big gauge is my normal boost gauge. Smaller gauge is hooked in line with the wastegate actuator. You can see the delay in getting pressure to the actuator to control the boost. You can also hear some kind of "whistling" sound (which is very faint in the video and best heard more towards the first couple of clips), which I think is the cbv. Here's the video.

Here's a pretty good screen shot that shows it plainly. I'm already past 20psi and there is no pressure on the wastegate actuator line yet.

Any ideas what is going on?

Modified by darag2358 at 9:07 PM 4-5-2009
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I have a feeling its the tune itself. I have heard of the ST ecu causing multiple people to bend rods and such over on Volvospeed.

btw: did you make that gauge pod or buy that one? i am working on one like that.
I made it. I still have to put the final touches and paint it.


Most of the people having problems with ST are people with other issues. I should call Oliver though and ask him about it. ECU is definitely a possibility, but I have to think it's probably something else going on that was brought to light with the higher boost.
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