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Building of Boost while in park

17K views 16 replies 12 participants last post by  a2elvis 
#1 ·
So this is a carry over from my other thread (my Exp w/a mtw stage 1 know a hybrid) but as you all know i have been dealing with surging issues and have tried just about everything their is to try. But Matt and Adrian had me perform a test the other day and that was to run the cold engine up to around 2200 rpm while in PARK and watch the boost. Well i would build 3-4# of boost. This means nothing to me as i dont know enough to say one way or the other but they say this should NOT happen under any condition while in park.

SO what say you all????
 
#2 ·
I don't see why that shouldn't happen. It's simple really, exhaust flow spools the turbo with higher RPMs there will be more exhaust flowing into the turbo before exiting the tail pipe so it will have to spool the turbo...
 
#4 ·
I've reved mine up with a stock turbo, don't recall letting it sit there with no boost registering. I would assume in park, the strategy won't allow the vanes to actuate. Idk. I geuss you will have every one sitting in their driveway now revving their trucks up to see if they build boost in park, lol.

Sent from my phone that somebody didn't help me get.
 
#5 ·
I thought the vanes did move while it's in park and idling. I know mine, without changing idle (ie; high idle/low idle) will change tone in the exhaust while idling in park in my driveway or wherever it's sitting. I assumed it was the vanes moving. :dunno:

I also know that if I rev it up high while in park, I can't get my boost gauge to move although I've never sustained a high RPM like that, just several quick romps of the throttle and it rarely went past 2,000 RPM while doing that. I'm curious about this myself.
 
#8 ·
i think the point of the test was to see if you could build boost while idling with the assumption being your vanes are stuck closed then you wouldn't be able to produce boost at lower rpms or at idle
 
#9 ·
Closing the vanes will spool it up. Opening the vanes stops the spool or essentially makes it like a non-vgt turbo where it relies soley on drive pressure to spool the turbo.
 
#10 ·
According to Matt and Adrian it should not EVER under any condition build boost while in park, they do not think i have a problem with the VGT as it is new and operates normally. I am sure one of them will jump in here and explain their thought process. I just wanted to know what everyone else saw and thought about it. My lack of knowledge is what part of my frustrations are as you get different theories from edeucated people that are completely different.
 
#13 ·
They all build boost in park. with the vanes closed it optimizes the little bit of exhaust flow across the turbine and makes it act like a smaller turbo.

This is the first test I do on a turbo that I suspect is stuck or a inop VGT solenoid, run RPMs up in part and manually control the VGT with the scantool, you will see an increase in boost and EBP with the vanes closed (85% duty cycle).
 
#14 ·
Bumped for Adrian
 
#15 ·
I tried this yesterday, when cold mine was making 4-5 pounds at 2200. Tried it again right after driving about 30 miles and it would only do about .5.
 
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