Whipple crew help... boost loss? 4th gear pull

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12-09-2009, 07:26 AM

#11

07VistaChicago

2nd Gear Member

Thread Starter

Join Date: Oct 2009

Location: Naperville, Illinois

Posts: 279

No other thoughts? I imagined with all of the expertise of the board we would have figured this out by now LOL!

12-09-2009, 09:12 AM

#12

hammeron

6th Gear Member

Join Date: May 2006

Location: Nicely done

Posts: 11,881

the only other thing it might be, is something
to do with the boost actuator. if for some
reason it is bleeding off at 4000rpms, that
might explain your issue.

although i'm not sure why it doesn't happen
in third also....maybe it's tune and engine
load related.

Quote:

Originally Posted by 07VistaChicago

No other thoughts?

12-09-2009, 03:27 PM

#13

07VistaChicago

2nd Gear Member

Thread Starter

Join Date: Oct 2009

Location: Naperville, Illinois

Posts: 279

Yeah I will probably bring it into Sutton's a local speed shop in the spring. Baby's sleeping for the winter.

12-09-2009, 11:28 PM

#14

Daryl06

2nd Gear Member

Join Date: Nov 2008

Location: British Columbia

Posts: 194

I'm no tuner but maybe your running lean and your computer is pulling timing to compensate?

12-12-2009, 09:19 PM

#15

moosestang

6th Gear Member

Join Date: Sep 2006

Location: Gainesville, FL

Posts: 11,278

Quote:

Originally Posted by 07VistaChicago

Well I would think the opposite, if there was belt slippage on the SC the boost would drop and the rpms would slow on their rise which is what seems to be happening. Clutch slippage I agree would increase engine rpms with no increase in drivetrain speed. I do have that when I WOT in 5th. All other gears seem fine.

If the belt is slipping, then you should see the boost drop or hold at a certain psi and not increase. How is your idler pulleys set up? Did it work fine before? Can you post a pic of your belt tensioner?

12-12-2009, 09:21 PM

#16

moosestang

6th Gear Member

Join Date: Sep 2006

Location: Gainesville, FL

Posts: 11,278

Quote:

Originally Posted by 07VistaChicago

No other thoughts? I imagined with all of the expertise of the board we would have figured this out by now LOL!

Who tuned it? Have you verified fuel pressure at WOT? This sounds like 1 pump isn't working and the ecm is killing power to save your motor. It's happened to a few people because something was installed right with the pumps.

12-13-2009, 09:49 PM

#17

07VistaChicago

2nd Gear Member

Thread Starter

Join Date: Oct 2009

Location: Naperville, Illinois

Posts: 279

Quote:

Originally Posted by moosestang

Well I boost up with all other gears so I am not sure belt slippage is the problem. So it works fine in all other gears that I can tell. I don't have an A/F or boost gauge. Next on the mod list.