Thread: 250 Loosing Boost at WOT
05-08-2009, 12:11 AM #1
250 Loosing Boost at WOT
OK this has been a problem for a little while, even before all the problems I had last year.......
If I am turning like low 7000's RPM I show 11.5-12 lbs of boost on my after market gauge, when I pin the throttle the rest of the way it drops @ 2 lbs of boost, I have had the engine out twice and intercooler in and out a few times so theres is no leaking hoses ,belts tight, so its nothing really obvious, unless I am over looking something.......
The question is how do you test the Primary Relief Valve, the one that is vaccum activated (what Kawi calls it in the Manual), the one in line, I have blocked off the over boost (What everybody calls the BOV), on the intercooler a long time ago..... I have been through the Manual a couple of times and the is nothing that I have found that really says anything about it or how to test it........
05-08-2009, 12:28 AM #2
I check and found my vavle to be leaking at WOT but running the OEM small vent hoses to outside the hull so I could see the end of the hose
I then put a ballon over the end of the tube and taped it on,and cut the end off the ballon.it was a long sausage ballon if you must know
Theory behind is as we know at engine VACUM loads its open/ bypassing
So at WOT if the valve is bypassis you will see and hear the air bleeding past the vavle, as you can hear it in the engine bay
Hope that makes some sence
05-08-2009, 12:46 AM #3
try swaping the Primary Relief Valve with a friend.
05-08-2009, 01:32 AM #4
We had a leaky bypass valve in our group. It's since been replaced.. BUT.. they aint cheap. Good start as Waz and chris suggested.
Has anyone experimented with an aftermarket bypass valve? Like the one we are discussing?
05-08-2009, 06:23 AM #5
05-08-2009, 07:05 AM #6
but it sound big like you my fiend.
05-08-2009, 07:45 AM #7
Sounds like a problem I had last year. If you have the stock air intake, the intake horn can come free from the intake duct and press against the hull not allowing air in the the intake. You should be able to reach your hand there a feel it.
05-08-2009, 08:01 AM #8
05-08-2009, 09:08 AM #9
It could also be a valve stuck open... You may want to take the head off and inspect your valves.
05-08-2009, 12:01 PM #10
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