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Jerking on slow deceleration

Posted: Mon Dec 10, 2007 11:45 pm
by mikerobison
'87 XR with MBC, Front mount IC, Super Sequential BOV, stock computer, T-9 Transmission, 3" exhaust. When I drive down the freeway and accelerate to maintain speed lets say to atmospheric pressure, 0 on the boost gauge, then decelerate slowly I get a violent jerking reaction through the drive line. (I don't get it when I quickly decelerate then press the gas pedal down to cruise speed. This leads to uncomfortable driving.)

I think it might be the BOV isn't releaving pressure and causing a pressure surge.... Any ideas?

P.S. This didn't start until I installed the FMIC and BOV.

Posted: Tue Dec 11, 2007 11:23 am
by xrattiracer
actually its likely that the bov is opening and letting unmetered air in/out.

Posted: Tue Dec 11, 2007 3:52 pm
by Ed Lijewski
Definitely look at/check the complete IC system. I'm reminded of a post some months ago (can't recall the exact description of the problem...) where after lots of sleuthing and head-scratching, the poster reported he found a small hole/leak in his IC which when fixed also resolved his problem. Point being that that's worth at least keeping in mind.

YMMV 8)

Posted: Wed Dec 12, 2007 12:46 am
by mikerobison
I couldn't imagine that a small IC/BOV leak could be causing this, because of how violent it is. I will investigate. Thanks, Mike

Posted: Wed Dec 12, 2007 1:05 am
by 86XR4Ti_John
Mike I had that once on my Talon, and it was the BOV for sure, swapped it out for another stocker and it ws no problem. Try another BOV and/or try to fix/setup yours?

Re: Jerking on slow deceleration

Posted: Mon Oct 29, 2012 3:39 pm
by mikerobison
The problem was the EGR valve went bad.

Re: Jerking on slow deceleration

Posted: Tue Oct 30, 2012 4:26 pm
by Grayson
An easy test is to simply clamp some 1" dowel rod in place of the BOV and head out for a drive. If the problem goes away, you know it's the BOV. BOV issues are cake to diagnose.