Heya guys - had my L for about 5 days now - I've noticed something from day one that I thought was a little odd...thought I'd give it a few days to read up on issues but have not seen it covered here.

Oh, and I'm pretty sure it's not the shift to 2nd boost dump that occurs - it's not happening at a shift.

So what happens is this : feather it in or nail it in 2nd gear, does not shift, boost builds, here we go!....boost builds up strong to 8lbs or so then stutters and drops to 1~3lbs for just a split second and picks right back up.

WAAAAAAAAHHHHHH-uhh-WAAAAAAAAAAHHHHH

Now again, it's not shifting (up or down) so I'm pretty certain it's not the boost dump...it's while it's in gear and it seems to only happen during WOT. The only thing I could think of was a slipping belt...

Any ideas?

 

mine does something very similar on a 3/4ish or harder throttle, but my boost doesn't drop off that hard. I was told it was a slipping belt so I went goodyear gatorback. Didn't fix it. Next I was told it was the TC locking up...

I would like to know what it is, too, assuming we are discussing the same thing...

KEn

 

Oh yeah, forgot to mention...

No screeching sound and no smell so I'm guessing not slipping...dunno.

Mine doesn't always seem to drop boost always to 1~3lbs, sometimes it's less but it sounds very similar to your issue. No drama or massive hesitation either...just very noticable drop of the screaming blower for just a blink...

 

now i think we are definitely talking about the same thing because the hesitation is so short, I don't really feel it so much as I hear it and it annoys me. Maybe I feel it because I hear it? Mine happens maybe 1 or 1/2 second BEFORE the 1-2 shift, so I know it is not the shift, either. It did it before and after a chip install so I don't think it is a fuel delivery issue.... A couple of my fellow HD folks have described a similar feeling as well.

check: http://www.f150world.com/forums/topic.asp?id=64052

Ken

 

LWM: Look for black, dust(rubber) on the aluminum casting behind the two upper idler pulleys or near the s/c snout. Should tell you if it's slipping.

I don't think it's slipping though or you would notice it at other times too???

May be the torque converter(normal?)?

Dan

 

I also notice a momentary drop in power at around 3,000 rpm during a WOT run. Nothing major, but noticeable. Definitely different from the 1-2 torque reduction. Someone a long time ago said it was the TC locking up, but that a chip would be able to take care of the problem.

 

I think it is your torque convertor locking up......it loads the motor and thus the crank can't spin the blower as fast.

--Joe

 

Yep, what Joe said

 

Unplug the boost bypass to be sure the computer isn't dumping boost due to a glitch in the program. With a roots positive displacement blower there's no way you could drop enough RPM's to get down to 1-3lb's of boost. Dropping the hammer at idle will get 7 or more lbs of boost so you'd have to drop below that RPM to get down to the 1-3lbs you mention.