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Thread: Random Reving

  1. #1
    Join Date
    Feb 2008
    Location
    Calgary AB. Canada EH!
    Posts
    380

    Default Random Reving

    My truck will randomly rev for a split second like someone gave the go pedal a quick shot. This has been going on for a few months now. Today it did it twice. Both times the truck was idling in gear. Could this be the last days for the PMD? or is it something else?

    Cheers
    93 2500 - best truck I ever owned
    Sold

    98 GMC Sierra 1/2 ton 4X4 EC SB Dark Blue
    3"turbo down to 4" back.
    Remote PMD
    Was S then F code now SSD ECM (used - it was cheap - not my first choice)

  2. #2
    Join Date
    Jan 2005
    Location
    L.I. NY>
    Posts
    233

    Default

    Same thing been happening with my truck for 8 or so years since Ive had it.
    feels almost like some one bumped you at a light or the truck just pops in and out of gear very quickly.
    I have replaced PMD for an unrelated failure and that little quirk is still there very infrequently,so I just live with it.
    I have seen threads that others experience the same Phenomenon, I do not think it is a serious issue.
    Dave
    99 sub 2500, 326,000mi, 4:10, 265-75-16 rubber, remote Dtech fsd and turbo master from Heath Isspro pyrometer and boost gauge-Kennedy, 1.94 TDCO, 3" custom bent exh.
    07 Suburban,08 LMM, Allison 6 speed.

  3. #3
    Join Date
    Feb 2008
    Location
    Calgary AB. Canada EH!
    Posts
    380

    Default

    Time to give this thread a bump. The matter is getting worse. Bouts of spastic reving repeatedly going on. It stops when I let my foot off the go pedal. Some days it's fine but others it becomes quite a rodeo. Any thoughts?
    93 2500 - best truck I ever owned
    Sold

    98 GMC Sierra 1/2 ton 4X4 EC SB Dark Blue
    3"turbo down to 4" back.
    Remote PMD
    Was S then F code now SSD ECM (used - it was cheap - not my first choice)

  4. #4
    Join Date
    Feb 2012
    Location
    Pauline, SC
    Posts
    618

    Default

    Might need to get some contact cleaner and clean all the wire connections & the ground points before winter gets here....

    It does sound like a PMD symptom, might wiggle the harness around and see if you can make it rev while you are wiggling the wires, may be loose somewhere....
    1993 Chevy K3500

    owner - Twisted Steel Performance

    porting, ceramic & powder coating

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  5. #5
    Join Date
    Sep 2001
    Location
    Ft. Wayne, In.
    Posts
    535

    Default

    The foot pedal is a potentiometer. Could it be that the "pot" is dirty and now intermittent? This could cause a intermittent reading of wide open, idle or anywhere in between.
    I've never looked at the schematic of the thing but some of the brands (probably all) use dual "pot" so that they can detect dirty segments of the "pot" and set a code.
    Hoping someone else like "DMav" or "More Power" can jump in here and comment.
    Dave
    Dave, N9LOV
    Member #242
    Dave's Diesels:
    Sold June, 07 '82 1/2 ton 4X4;340k miles
    '97 2 Dr Tahoe, Intercooled,
    Kennedy ECM, 4" Exhaust
    '02 GMC

  6. #6
    Join Date
    Apr 2001
    Location
    CA
    Posts
    13,573

    Arrow

    Quote Originally Posted by DieselDavy View Post
    The foot pedal is a potentiometer. Could it be that the "pot" is dirty and now intermittent? This could cause a intermittent reading of wide open, idle or anywhere in between.
    I've never looked at the schematic of the thing but some of the brands (probably all) use dual "pot" so that they can detect dirty segments of the "pot" and set a code.
    Hoping someone else like "DMav" or "More Power" can jump in here and comment.
    Dave
    Not the APP (pedal). It has 3 independent circuits. Any of the 3 failing will set the STS (Service Throttle Soon) lamp and code. 2 failing will set limp mode, and 3 failed won't respond at all. Even if only intermittent.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  7. #7
    Join Date
    Feb 2008
    Location
    Calgary AB. Canada EH!
    Posts
    380

    Default

    I have no codes. What are the possibilities it is IP related? This is really weird. I have a remote pmd and a known good pmd still attached to the pump. I will plug in the one on the pump and see what happens.
    93 2500 - best truck I ever owned
    Sold

    98 GMC Sierra 1/2 ton 4X4 EC SB Dark Blue
    3"turbo down to 4" back.
    Remote PMD
    Was S then F code now SSD ECM (used - it was cheap - not my first choice)

  8. #8
    Join Date
    Feb 2008
    Location
    Calgary AB. Canada EH!
    Posts
    380

    Default

    It was cold this morning and the colder it gets the worse the situation becomes. Seems to resolve itself as it warms up. It was so bad this morning she finally went into limp mode. I pulled off the road and restarted it and all is well. I'm scratching my head.
    93 2500 - best truck I ever owned
    Sold

    98 GMC Sierra 1/2 ton 4X4 EC SB Dark Blue
    3"turbo down to 4" back.
    Remote PMD
    Was S then F code now SSD ECM (used - it was cheap - not my first choice)

  9. #9
    Join Date
    Feb 2008
    Location
    Calgary AB. Canada EH!
    Posts
    380

    Default

    I plugged in the original PMD on the IP and the situation seems to have resolved itself. I will repost in a week to give it a fair test. Supposed to snow here on Tuesday.
    93 2500 - best truck I ever owned
    Sold

    98 GMC Sierra 1/2 ton 4X4 EC SB Dark Blue
    3"turbo down to 4" back.
    Remote PMD
    Was S then F code now SSD ECM (used - it was cheap - not my first choice)

  10. #10
    Join Date
    Feb 2008
    Location
    Calgary AB. Canada EH!
    Posts
    380

    Default

    Problem fully resolved. It was the FSD. I don't think I heard of one going south with these particular symptoms. It was a Dtec remote mounted.
    93 2500 - best truck I ever owned
    Sold

    98 GMC Sierra 1/2 ton 4X4 EC SB Dark Blue
    3"turbo down to 4" back.
    Remote PMD
    Was S then F code now SSD ECM (used - it was cheap - not my first choice)

  11. #11
    Join Date
    Dec 2003
    Location
    Yukon Canada
    Posts
    1,612

    Default

    Hi Dave
    How long did the Dtech last?Months KM's?
    Any comparison to previous FSD's in longevity?

    Thanks Thomas
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  12. #12
    Join Date
    Feb 2008
    Location
    Calgary AB. Canada EH!
    Posts
    380

    Default

    It lasted less than two years. The Stanadyne on the pump is older than that and still works. However you can't make a decision based on one case. I will replace it with another Dtech and we shall see how it goes.
    93 2500 - best truck I ever owned
    Sold

    98 GMC Sierra 1/2 ton 4X4 EC SB Dark Blue
    3"turbo down to 4" back.
    Remote PMD
    Was S then F code now SSD ECM (used - it was cheap - not my first choice)

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