If you are not able to login to the forum, please Contact Us here to let us know. Thanks!

Support FSC and see no ads! - Click Here
Results 1 to 8 of 8

Engine missing when accelerating

This is a discussion on Engine missing when accelerating within the Technical / Maintenance forums, part of the General Discussion category; '93 5.7L, GMC My truck hesitates and misses when I am accelerating. It doesn't do this all the time, but ...

  1. #1
    Registered User
    Join Date
    Aug 2004
    Location
    Alabama
    Age
    39
    Posts
    25

    Engine missing when accelerating


    Support FSC and see no ads! - Click Here
    '93 5.7L, GMC
    My truck hesitates and misses when I am accelerating. It doesn't do this all the time, but most of the time. It is like a "plug wire off" kind of miss, but I can push the gas pedal on down and it will clear up and it will go on. Truck starts good cold and hot. There is no "Service Engine Soon" light (no codes).

    I have changed the plugs, distributor cap/button, new fuel filter, new air filter. Checked all the plug wires. All of them look good. They were replaced about 50k ago with AC-Delco wires.

    Any suggestions? What about the injectors or fuel pressure regulator. Would they cause it to run like this? I don't think the O2 sensor has ever been replaced, would it cause something like this?

  2. #2
    Registered User
    Join Date
    Mar 2005
    Location
    In the Shop
    Age
    45
    Posts
    159

    Re: Engine missing when accelerating

    If plug wires are good also check EGR valve to see if it is opening to much to quickly.

  3. #3
    Homesick NBer
    Join Date
    Jul 2005
    Location
    Edmonton, AB (but still an easterner at heart)
    Age
    29
    Posts
    2,395

    Re: Engine missing when accelerating

    Quote Originally Posted by dieknow
    If plug wires are good also check EGR valve to see if it is opening to much to quickly.

    egr, definatly, mines doing this, and have narrowed it down, 100% sure.

    also, does it do it while you are cruising, at a given speed, and clear up when you step on it, or is it just upon first acceleration, cause if it does it at cruising, might be a bad distributor shaft, had this problem but got it fixed, now a bad egr, go figure.
    Last edited by kenman1717; 02-08-2006 at 04:37 PM.
    2003 Chev Silverado 4x4 4.10 gears and it has a 4.8L
    1997 GMC Sierra 4x4 4.3L 4L60E KOSS CD player,16mpg,3.73 gears z71 skid plates <<<sold

    4th year apprentice at Chev Dealer

  4. #4
    Registered User
    Join Date
    Aug 2004
    Location
    Alabama
    Age
    39
    Posts
    25

    Angry Re: Engine missing when accelerating

    A little more history about this problem... To begin with, the truck did not want to start one day after I stopped and ate lunch. I had to spin it over a long time with the gas pedal on the floor. When it did start a bunch of black smoke came out the pipes. It was definetly loaded up with gas. I figured it was time for a tune up, so I replaced the fuel filter, plugs, distributor cap, rotor button, and plug wires. This helped the starting problem. It would start and idle fine, but there were still times when it would stumble, spit and cough. When it starts this, it is like it is way out of time... no power at all. I have to keep patting the gas and slowly feeding it. Some days this is worse than others, but I could tell that it was getting worse and worse.

    Saturday I ohmed the ECT and checked the voltage on the MAP sensor. I visually checked the EGR just to make sure it moves when the motor is reved. I also removed the EGR to make sure the intake was not clogged. Every thing checked O.K.. I thought that the ECT was slightly off, but should have been close enough to not cause any problems.

    This morning, the same coughing, spitting and stumbling (it was 25f). I stopped by Autozone this afternoon after work (50f) and picked up a ECT. Made it about 4 miles down the road and had to stop at a friends. Truck had lost all power. Would only go about 20MPH on level road. Put in the new ECT and truck ran good for about 5 miles down the road, then started the crap again.

    Finally got the POS home, now it will not even start. Still no "Service Engine Soon" light. The bulb is not shot. I checked the codes by jumping A+B and turning the ingition to ON. All I get is code 12. It will hit when I am turning it over, but it just will not pickup and start running.

    Any suggestions short of gas and a match are very welcomed.

  5. #5
    Homesick NBer
    Join Date
    Jul 2005
    Location
    Edmonton, AB (but still an easterner at heart)
    Age
    29
    Posts
    2,395

    Re: Engine missing when accelerating

    Quote Originally Posted by LincolnLooser
    A little more history about this problem... To begin with, the truck did not want to start one day after I stopped and ate lunch. I had to spin it over a long time with the gas pedal on the floor. When it did start a bunch of black smoke came out the pipes. It was definetly loaded up with gas. I figured it was time for a tune up, so I replaced the fuel filter, plugs, distributor cap, rotor button, and plug wires. This helped the starting problem. It would start and idle fine, but there were still times when it would stumble, spit and cough. When it starts this, it is like it is way out of time... no power at all. I have to keep patting the gas and slowly feeding it. Some days this is worse than others, but I could tell that it was getting worse and worse.

    Saturday I ohmed the ECT and checked the voltage on the MAP sensor. I visually checked the EGR just to make sure it moves when the motor is reved. I also removed the EGR to make sure the intake was not clogged. Every thing checked O.K.. I thought that the ECT was slightly off, but should have been close enough to not cause any problems.

    This morning, the same coughing, spitting and stumbling (it was 25f). I stopped by Autozone this afternoon after work (50f) and picked up a ECT. Made it about 4 miles down the road and had to stop at a friends. Truck had lost all power. Would only go about 20MPH on level road. Put in the new ECT and truck ran good for about 5 miles down the road, then started the crap again.

    Finally got the POS home, now it will not even start. Still no "Service Engine Soon" light. The bulb is not shot. I checked the codes by jumping A+B and turning the ingition to ON. All I get is code 12. It will hit when I am turning it over, but it just will not pickup and start running.

    Any suggestions short of gas and a match are very welcomed.

    just an idea, get you cat cnovertor checked, sounds like its plugged.
    2003 Chev Silverado 4x4 4.10 gears and it has a 4.8L
    1997 GMC Sierra 4x4 4.3L 4L60E KOSS CD player,16mpg,3.73 gears z71 skid plates <<<sold

    4th year apprentice at Chev Dealer

  6. #6
    Registered User WinterBeater's Avatar
    Join Date
    Sep 2003
    Location
    MI
    Posts
    12

    Re: Engine missing when accelerating

    I had a similar problem. It was a problem with the plug wire. The short one that leads to the distributor had corroded inside the sheathing and I could not see a problem with it. After months of messing around I replaced all the plug wires and fixed the problem. Upon closer examination I found the corroded wire.
    1994 GMC 1500
    Star conversion
    Magnaflow exhaust
    20" wheels.

  7. #7
    Registered User
    Join Date
    Feb 2006
    Location
    Minnesota
    Posts
    1,189

    Re: Engine missing when accelerating

    Another possibility is the ignition module in the distributor. These things can act very goofy sometimes. My 92 would be running fine and then start spitting, sputtering and losing power. I would slow down to pull over and it would die and not start. Try it two minutes later it would start and as soon as I would start driving it would loose power. Changed the plugs, wires,cap,rotor,fuel filter and pulled the distibutor and checked the bushings and they were fine. I even replaced the pickup coil while the distibutor was out and it still ran like crap. I replaced the ignition module and the problem was solved and that was 30k ago.

  8. #8
    Registered User
    Join Date
    Aug 2005
    Location
    MN
    Age
    44
    Posts
    55

    Re: Engine missing when accelerating

    Try plugging the vac line from the egr to the throttle body with a screw once it's warm and see if it stops. If it does, then it's the egr. I think I've narrowed mine down to the egr, I plugged it up last nite after it was doing that same thing on the way home, took it for a cruise and it seems to have cured it.

    Looks like I'll be replacing my egr in 10* F temps this weekend
    If it ain't broke.........fix it till it is!

 

 

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •