misfire

  1. B

    Weird engine stumble / misfire

    Sorry if this is the wrong place to put this thread I’m new to the forum and only really use facebook groups. This is kind of a long one but my truck was running good until I switched over to an mpfi spider injector system (a “reman” acdelco unit from a guy on eBay) and after installation the...
  2. RP95

    Misfire when making a right turn

    Got a weird one for you guys 1998 K1500 5.7 Vortec 4L60E 220,000km A few days ago the truck developed an intermittent misfire. This occurred during very heavy rain for 3 straight days, I had hit a couple deep puddles and sucked in some water through the air cleaner, I blamed that initially...
  3. D

    The dreaded PO300

    Well I, like many, have recently been hit with the dreaded PO300 intermittent misfire code. From my code reader live data is showing me that it’s cylinders 3 and 7 misfiring showing on the misfire diagnostic page. I so far have checked fuel pressure (50lbs KOEO- as well as KOER, 50 for both)...
  4. H

    1997 4.3 V6 Occasional Random Misfires

    Hello all, I have a 1997 Chevy C1500 Work Truck 2WD Single Cab long bed boring edition (I love this truck don't get me wrong) with the 4.3L v6. I've got 207k miles on it. I bought this truck with right around 200k and recent maintenance records and the previous owner took it for every service...
  5. C

    Weird Misfire Issue

    So my 1994 Chevy k1500 5.7 TBI has a weird issue where randomly it will get the misfire tick and I can feel it in the pedal. Lose some power and sounds like crap. Then to fix it I turn off the truck for 1-2 minutes fire it back up and in park rev the motor to the rev limiter twice. Then the...
  6. K

    Advice Needed: Slight stutter/shudder/jumpiness between 70-80 mph

    Hi, I have a 1999 GMC Suburban 1500 2wd. Recently I’ve started to notice what can best be described as a stuttering or feeling of a misfire between 70 and 80 mph. The feeling is most consistent at 75mph. However, I have no fault codes at all. I did a test and tapped the brakes to reset the...
    • kephas
    • Thread
    • lockout misfire over drive overdrive shudder stutter transmission
    • Replies: 5
    • Forum: Transmissions
  7. zampman

    Is the crack in the porcelain on this spark plug enough to cause rough running?

    Evening gents, '97 K1500 with a 305. Just did timing chain, lower intake gaskets and new exhaust with O2s. Had some rough running, found my fuel trims high, and one of the new O2s not doing anything. Found exhaust doughnuts leaking, so tightened up the bolts on the doughnut flange, and saw...
  8. D

    96 chevy cylinder 6 misfire

    Need help figuring out my misfire on my truck I've done a lot and I still can't figure it out, I've done spark plugs, wires, new disturber, fuel pump, cam shaft postion sensor, new map sensor and fuel regulator. I can't figure out what the problem is, so I'm seeking some hlep figuring it out...
  9. M

    Engine runs like garbage; cant get a straight answer on whats wrong.

    About a year ago, i was taking my truck (‘93 C1500) back from a 100 mile trip, when the engine (305 small block) suddenly started running horribly. I hadn't heard any sounds from the engine beforehand, but i still think its some internal problem. I recall the temperature gauge giving me errors...
  10. G

    Multiple Performance mishaps

    Me and my son recently got another OBS for a steal but knew it had some quirks. The lady who sold it to us said that the oil pump was bad and that’s why it wouldn’t start? Turns out it had a dead battery, replaced it and started with great oil pressure. She had already bought the parts and the...
  11. J

    98 K1500 Suburban fuel pressure issues

    98 suburban 5.7 csfi has new fuel pump which could be the issue I'm just trying to make sure, the issue I'm having is hard starts,drives great until warm up( truck currently has 170 tstat I put in after radiator swap the parts store gave me a 170 in a 195 box and I needed it to be up and running...
  12. A

    Light random all cylinder misfires 97 5.7 vortec

    Hello all, I’m going to start with everything that has happened so far. And I’m sorry this might be long. While traveling to work one evening, the truck died on me. I quickly diagnosed fuel pump because it sounded awful. Got it towed back to the house and started taking it apart. Before...
  13. T

    Random Misfire Between 1500-2500 RPMs

    I've got a 1996 Chevy C1500 with a 5.7 vortec and it's a got a weird misfire under heavy throttle or high or low RPMs it runs smooth no misfires but when you try to hold anywhere between 1500-2500 rpms it misfires randomly it's not a dead cylinder sometime it will misfire once every 5 seconds...
  14. K

    94 k1500 misfire at idle after being overheated

    My 1994 K1500 with the 350 tbi has had what I believe to be an intermittent misfire at idle for a while now. The truck would always idle very low and pop occasionally since I got it but recently it has gotten worse and the idle has started to cutout and come back when in gear with foot on the...
  15. HighRoadZ71

    Misfire, 60-70mph at Cruise

    Hi all, relatively new to the forum but spend a good amount of time lurking. I have a 1999 Tahoe Z71 5.7 Vortec. I bought the truck last February, and around September it developed a misfire at highway speeds, but only when ascending a hill trying to maintain 65-75mph. The truck had roughly 183k...
  16. S

    99 Tahoe and Cylinder 3 misfire p0303

    Hi i've been dealing with a single cylinder misfire p0303 for a while now. It has new mpfi injectors (even bought one single injector and tried replacing that one), spark plugs, intake gaskets, ign wires, distributer cap and rotor. Motor has 300,000 Miles. it's also been 0411 swapped. I've done...
  17. C

    Occasional bucking and sputtering at crushing speeds over 65

    I have a 92 k1500 5.0 nv4500, used to be 4.3 but I swapped a 5.0 in it. the issue I'm having is after accelerating on the interstate on ramp the truck will buck and sputter and backfire while trying to maintain speed, it will go away if you let off the gas the tiniest amount but then will start...
  18. S

    89 5.7 TBI sputters under load once warm

    Hello, I'm working on a 89 chevy with a 350 TBI and I'm trying to figure out this issue. The truck starts up fine and idles normal, I can rev it no problem upon first start up but as soon as she starts to get warm and also once up to temp when I rev or accelerate she starts to sputter and has no...
  19. D

    New MPFI Spider Injection caused Engine Seizing????

    Hey ya'll, I have a '98 K1500 with a 5.7 Vortec (vin code R). The truck has 230k on it, so i decided I would do the MPFI upgrade. I figured it had the original CFI in it. Well, I took it apart and discovered it already had an FJ504 (O'Reilly's) injector in it. Being as I had a brand new one...
  20. T

    idle dipping while stopped

    I have a 1988 k2500 that starts immediately and idles very well. However once the truck gets to operating temperature the idle will dip for a split second when I'm stopped at red light. I have also noticed the dips get worse the longer I idle while in drive. The truck has never stalled when this...
  21. D

    1997 5.7 Vortec misfire/stumble

    Hello everyone I have a 1997 Suburban that's giving me a fit. Generally can diagnose anything but after thinking for a few weeks and trying a few things I'm interested to hear some ideas outside the box. Truck only has 120k original miles. The issue I have is when it warms up and goes into...
  22. rickwolhoy

    5.7 vortec random misfire HELP

    Hey all, I've been grappling with a random misfire for a while now. I have a 2000 chevy tahoe z71 with the 5.7 vortec, currently at 322k miles. About a year ago I had a bad misfire at idle on cylinder 3 and after a leak down test I found that the exhaust valve was leaking way beyond spec. I...
  23. S

    1997 K1500 5.7, new cylinder heads and gaskets, started and ran for a short while now wont start at all

    Hello, I have a 1997 K1500 5.7 Vortec. About a month ago, I was driving my truck and it was running beautifully. The engine was smooth, the transmission was shifting nice and the AC was blowing ice cold. It was a great day. I was driving down a road when suddenly I felt like the engine was...
  24. 0

    2000 454 rough idle and acceleration while cold

    I’m stumped and hope someone can help. 2000 454 k2500, hard starting, will crank forever unless you give it some gas and it’ll stumble to start, but once it does it idles at 750-850 rpm (normal?) but seems to have a misfire and you can smell gas out the exhaust. While it’s still cold (100-120 on...
  25. 2doortahoetoby

    Best choice for MPFI

    Long time viewer and reader of the threads here but I just want any possible new ideas or information on the topic. I know a lot of people recommend the mpfi conversion, and I have been needing to put a new spider in. I have been having a misfire code that won’t go away. I did my intake gaskets...

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