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'93 1/2 truck sputtering and jerking at low rpm's

This is a discussion on '93 1/2 truck sputtering and jerking at low rpm's within the Technical / Maintenance forums, part of the General Discussion category; Hey ya'll, just became a member a hope ya'll could shed some light on my problem. I have a '93 ...

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    '93 1/2 truck sputtering and jerking at low rpm's


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    Hey ya'll, just became a member a hope ya'll could shed some light on my problem. I have a '93 1/2 standard cab truck with 350ci-auto tranny. When I'm driving at around 1,200-1,500 RPM the truck starts to jerk like it's running out of gas or something and when I give it gas it runs fine. I replaced the fuel pump about 2 yrs ago, I just yesterday changed the fuel filter, dist. cap and rotor. Since I changed the fuel filter it seems to have helped the hesitation when starting off slow but I've still noticed the jerking when I'm running at low RPM'S-any guesses?? Also, I need to do a front brake job and was wondering if anyone has some good ideas on what brand rotors and pads I should get-I would like to keep it at an affordable price(under $80 per rotor)-I would like to look into cermamic pads b/c of less brake dust. Any suggestions?? I've looked into Bendix but does anyone know of other brands that they have had success with..? Thanks for your help!!

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    Will
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    Re: '93 1/2 truck sputtering and jerking at low rpm's

    when the jerking starts do the RPMS jump up and down or stay steady?
    1991 Chevy Silverado shortwide, 2wd, lowered 4/6
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    Re: '93 1/2 truck sputtering and jerking at low rpm's

    Haven't really noticed if the RPM jumps or not-but it's enough of a jerk to throw your body back and forth when it happens-what do you think about it flattopwill

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    Re: '93 1/2 truck sputtering and jerking at low rpm's

    Do it do the jerking when your coming to a stop (when your foot is lite on the brake pedal?) and then when you go to give it gas it hesitates?
    1996 Chevy Silverado 1500
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    5.7L Vortec 350
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    Re: '93 1/2 truck sputtering and jerking at low rpm's

    Sounds like a missfire....I had a simmilar problem when i bought my truck, tuned it up with rotar, cap, plugs, and wires, fuel filter (which youve done), and a bottle of injector cleaner in the tank,,,,fixed the prob.

    I could only feel the shake at low rpm's like you......is your truck throwing up any OBD codes? -if it's a missfire it should-


    Another thing could be the U-joints on the drive shaft. I kinda doubt by the way your describing your problems, If it's the U-joint you will notice violent shakeing at higher speeds, ticking (sounds like gears ticking in the rear end) or shakeing when your foot is off the gas and your brakeing. Just get under your truck and check the drive shaft for any play.....I doubt that's it tho

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    Re: '93 1/2 truck sputtering and jerking at low rpm's

    Well it doesn't do it when I let off the gas and apply the brake-only when I'm on the gas very lightly does it do it. I can be at 10mph or 45mph and very lightly on the gas and it will start to jerk. I have noticed lately that there is a ticking noise coming from the back on the truck-I too thought that it may be u-joints. I just don't know exactly how to test if u-joints are bad. Any more suggestions would be appreciated!! Thanks....

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    Re: '93 1/2 truck sputtering and jerking at low rpm's

    hmmm i don't think it's your u-joints, but possibly....

    -get in your truck and put your foot on the brakk, shift back and forth from drive to reverse, you might hear your drive shaft clunking or slaming indicating play in it i.e. u-joints

    -umm another way maybe is put your park brake on, block the tires and put your tranny into neutral, while it's like this crall under and check for side to side play at the joints

    -if you "got on" the pedal a little from a dead start do you feel shaking, or hesitation?



    and finally, when's the last time you did a tune-up (plugs, wires, cap, rotar?).....still could be a missfire

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    Re: '93 1/2 truck sputtering and jerking at low rpm's

    Well I just did a complete tune up and still not any better. A friend told me it might be a vacuum leak problem-I don't know what to do, I guess I'll just take it in somewhere and let them look at it.

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    Re: '93 1/2 truck sputtering and jerking at low rpm's

    Well I just did a complete tune up and still not any better. A friend told me it might be a vacuum leak problem-I don't know what to do, I guess I'll just take it in somewhere and let them look at it.

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    Re: '93 1/2 truck sputtering and jerking at low rpm's

    I've had about my fill of this problem but one more thing-I was thinking maybe it's a loose timing chain...?? Does anyone think that could be the case..?
    1993 Blue/Grey Chevy Shortbed Reg. Cab, 350c.i., 4L60E Trans., K&N Filter, MagnaFlow Duals with 3" Tips, 275/60/15 BFG'S, and otherwise stock just like I like it!!!! GO HOGS!!!!!

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    Re: '93 1/2 truck sputtering and jerking at low rpm's

    Worn timing gears & chain?

    Yes that could well be the cause.

    I have a '94 K1500 with a 350 that was driving me crazy. I had it in at the Chev dealer a couple of times to have them scan it and after several hundred of dollars worth of other parts it still had an idle/low rpm surge. Under load it had plenty of power and not the slightest bit of a miss. At low rpm cruise it jerked and bucked like a novice driver was working the clutch.

    I asked the dealership several times if they had checked the chain and they said - and I quote - "We have NEVER had to replace a chain on one these engines." After taking it to a private shop I insisted that they check the chain. Once again I heard the story about these chains never wearing enough to cause problems.........................

    A few weeks ago I put a breaker bar on the crank and took off the distributor cap to look at the rotor. You guessed it! 15-18 degrees of slack at the crank.

    Taking the timing cover off revealed that the chain had been so loose it was starting to mark the inside the cover and had over an 3/4" of slack on BOTH sides of the gears when the slop was even on both sides.

    A new chain and gears and the engine once again purrs like a kitten! It looks like the ECM was chasing the timing at low non-load rpm but when load was put on the chain the ECM was able to hold the timing, for a while at least.


    Another problem I had a few years ago with the same engine was the distributor reluctor wheel had come loose and was slipping back and forth about 10 or 12 degrees. This problem however had different symptoms in that at times it was hard to start - way over-advanced - but once started the ECM was able to compensate and keep the engine running smoothly.

 

 

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