hey all...

I have some questions.

I have a t62-1 with an hks divided housing, 1.0 ar, unclipped ptrim, 3.5 inch dp, etc....

was to dyno tune yesterday but while tuning on the street it falls from 17psi (high boost) to 15psi at 6000-6500 rpm's.

There are no boost leaks. It simply will not hold boost.


Any thoughts from you all are appreciated.


jason

 

I had the exact same thing happen to me this Saturday.

I did a search, and figured out the problem. In my case,
it was that the Gain on my Profec B was set too sharp.

I set it in the middle, and now there is no more problem.

 

My first guess is as always with the profec B check the settings on there, the overboost limit setting. This number represents your upper threshold of boost - the amount of boost you do not wish to exceed. This is helps out alot, setting this function up correctly eliminates you having to adjust your boost based on weather conditions. If/when boost reaches this level, it will give you an audible beep, and the display will turn red. You should set this slightly above your target boost. not sure if that is it but it has happened to a few peope without knowing about it.

 

Remember on the spec I (not sure about the others)but you have to change the settings on the back to match your type of wastegate. But it really sounds like a boost leak!

 

there was some thought that the unclipped wheels were causing it to not flow properly at high boost and high rpm...but I was corrected in that the turbo wouldnt have flow probs til at least twenty pounds even with unclipped vs clipped wheels.


steve kan is doing the tuning...the boost controller is set up properly.


J

 

If steve has the car, have him replace the wastegate spring to something like a 17 or 20 PSI unit. Then try again with no boost controller, just running the wastegate vacuum line.

If the turbo achieves 20 psi; then you know the boost controller solenoid is having problems. If it cant, then it could be the turbo.

 

sounds like wastegate issues..put a stiff spring in there... or try a different wastegate with a bigger sized diaphram


good luck!

 

I'm having the same problem. yours sounds like a wastegate problem though. what psi spring is in it now? I currently have a 10psi spring and im losing boost to about 15psi at 7000rpm, but my wastegate is audibly closed (vented to atmosphere). My problem is the restrictive racing beat exhaust. You're not running a cat are you?

 

Yep, I wonder what the current WG spring rate is?
Too soft of a WG spring trying to run too high boost (due to a boost controller) can cause uncontrollable boost issues.

5psi spring will cause this.
7psi is borderline.
10psi or higher rate, it should be okay.


-Ted

 

with a 6.7 psi spring, I had boost drop down to 13 psi

 

I believe it is a 10psi spring...I will ask again to be sure.

I run a 3.5 inch dp...a flowmaster where the cat should be....and the greddy titanium catback. there is no restriction at all. the whole exhaust is brand new from dp to catback.


j

 

steve kan is doing the tuning...the boost controller is set up properly.


J[/QUOTE]


Steve did the tuning on mine as well. He pulled up a page on his labtop to show me the correct settings on the profec B. We ran into boost issues and could not get the car to boost above 10psi. When I got home I went to the Greddy site and found the profec was set incorrect! Along with tightening down the wastegate and setting the correct settings on the boost control it solved my problem.

 

most of time will be wastegate spring. This happend to my HKS T04R turbo kit. I had 10 psi spring. and when setting to 14 psi. it will rise to 14 psi and drop to like 13 or lower on high end

 

If the boost controller is set correctly then go to the spring, again check the setting on the controller if there is no warning of the controller check the gain it doesn't hurt to do this more than once at the very least you will also learn how to adjust it in the process. If the problem still persists I would run a higher spring pressure no boost controller and see where your at.

 

I still have this problem =] I just switched to a 1bar spring. I hold boost clear up top now (Which is why im leaving it in) but it did nothing for the dropoff.

 

Your exhuast is causing the drop-off.
Stop jacking threads and keep to your own threads!


-Ted

 

ted, youve been a forum **** lately, a bump isnt gonna hurt his thread =]