Bathurst

Ok so after the fresh rebuild I tried boosting yesterday. The primary was coming very strong as I could notice during the run in period also but when I tried going past 4500 rpms the boost dropped to 0. I slowed the car down and tried again this time the primary boost also did not come so I stopped and checked and the upper intercooler pipe had come loose so I tightened it and again I got primary boost but when I floored the car at secondary transition i felt the exact same thing so i stopped and checked all the intercooler pipes and Y pipe were ok no leaks so I checked and the blow off valve came off the Y pipe so I put a new clamp and again the primary boost was ok. Now when i floored it I got perfect primary boost and good secondary boost started coming but then again something gave and I lost boost. Now I get around 3-4psi of boost in the primary and the same in the secondary. What should I look at next....

CloudPump

iTrader: (2)

From what you were intially describing I would have thought that your Charge Releif Valve was stuck open.

Start with this:

http://www.autosportracetech.com/RX-...leshooting.htm

-Geoff

Bathurst

Thanks Geof...

Here is an update guys.. So I parked the car yesterday with the same condition as described above and today I took it out for a spin... Again I get great primary boost... I boosted the primary till 4300 rpms like 10 times and everytime it was spot on. But as soon as I went above 4500 rpms the secondary tried kicking in Half heartidly and then took the primary with it too. I mean after that the primary would not come as it should but would just spool right before hitting 4500rpms transition point and then go away and the secondary kicks in weak. What could the problem be that until I stay with the primary only(below 4500rpms) it performs great no matter how many times i boost below 4500rpms but as soon as the transition point comes it messes the primary and the secondary is already messed up... I have a video which I will try to post here also of the issue...

Bathurst

http://www.youtube.com/watch?v=CcVbhtsj8AM

CloudPump

iTrader: (2)

Just throwing things out there, but:

It could be that your Charge Control Valve (the butterfly that opens in the Y-Pipe to switch between primary and secondary turbo's) is being opened at 4500 rpm (as it should) and then not closing when it's going back under 4500. This coupled with a bad Charge Relief Valve (which vents the secondary turbo pre-spool before it becomes active) would be dumping your secondary boost over 4500 out the CRV and if the CCV is being prevented from closing after it initially opens it would vent your primary boost out the CRV.

I wouldn't put a lot of money on it, but you can test this pretty easily.

When you start your car if you look down at the back half of the Y-Pipe you should be able to see your Charge Control Valve's actuator arm pull in. Go for a drive and force your loss of all boost after going over 4500. Quickly park the car, leave it running, pop the hood and look to see if the arm on your CCV is pulled back in (as it should be) or staying open which would indicate something being wrong.

-Geoff

Bathurst

Thanks Geoff... That's exactly what I was looking for
.. A lead... Its been raining since last night. Will take the car out and do as you have advised as soon as it clears and report back..


Thanks again...

dblboinger

iTrader: (3)

I've got something similar going on, with a twist. FYI, I'm running stock turbos and just installed a Power FC. Anyway, I did the 3rd gear boost test for the 1st time today and I found my boost increases smoothly up to 15 psi then at about 4500 rpm it drops to like 5 or less. If I slow down to about 25mph or so then redo the test it does the same thing, boosting smoothly up to 4500 then drops. I did it like 6 or 8 times and the same every time. First thing...I didn't think stock turbos would make that much boost. How can I test the accuracy of my boost gauge? Unfortunately I didn't think to put the Power FC into "Hold" mode to see what kind of boost it was seeing. Second, wtf would cause this problem? I'm not very knowledgeable on turbo systems...but I'm trying.

moconnor

iTrader: (14)

Are you tuned for 15psi? If not, turn down boost. Base map on PFC is tuned for ~13psi.

dblboinger

iTrader: (3)

How do you turn down the boost? I didn't think stock turbos would produce 15psi.