Jump to content

Skipping 350

wmf1964

By wmf1964
in Ask A GM Technician

Recommended Posts

wmf1964 New Member

wmf1964

Posted
Posted

hello everyone, i have a problem with my truck running rough and has a miss at idle and while driving. i have replaced everything i can think of that may cause this problem and its still there. the items ive replaced are cap,rotor,pickup,plugs,coil,wires,module,ecm,replaced intake and gasket, tbi gasket,replaced egr valve 3 times with known good uesd ones, replaced injectors twice with known good used ones, replaced fuel pump and fuel filter, used 7 cans of carb cleaner and 2 bottles of soapy water to check for vacuum leaks. i just noticed that when i press the brakes it changes the rpms of the engine,so i think the booster may be leaking vacuum. i blocked off the vacuum from the booster and it still idles rough with a miss. the engine is new with less than 300 miles and has 140-150 lbs of compression per cylinder, and does not give any trouble codes. ive readjusted the valves 3 times and all are moving like they should. i have made my living for 20 years as a mechanic but i need some help on this one. for some reason i cant seem to fix my own now. I REALLY NEED HELP WITH THIS ONE. thanks

95Sierra2500 Senior Enthusiast

95Sierra2500

Posted
Posted

With everything you've replaced, I think it's time to start troubleshooting. Since you're TBI, you should be able to tell if you're getting good fuel or not based on how the injectors are spraying. Next I'd say pull each plug wire one at a time (replacing it afterwards) to see if engine behavior changes. It should be noticable with each plug wire coming off, but if it doesn't change on one particular cylinder then you've found the problem.

 

A few things to consider: Did you check the timing and set it properly? Are you sure you don't have a cracked head? What kind of plugs/wires did you use? There's alot of variables and without seeing the thing I have a hard time telling you where to start.

wmf1964 New Member

wmf1964

Posted
  • Author
Posted
With everything you've replaced, I think it's time to start troubleshooting. Since you're TBI, you should be able to tell if you're getting good fuel or not based on how the injectors are spraying. Next I'd say pull each plug wire one at a time (replacing it afterwards) to see if engine behavior changes. It should be noticable with each plug wire coming off, but if it doesn't change on one particular cylinder then you've found the problem.

 

A few things to consider: Did you check the timing and set it properly? Are you sure you don't have a cracked head? What kind of plugs/wires did you use? There's alot of variables and without seeing the thing I have a hard time telling you where to start.

 

 

ive done so much i just forgot to list that the timing was set at tdc with the wire unpluged. each plug wire has been removed one at a time and a difference was noticed. the heads were rebuilt at our local napa store and checked for cracks. there were given a clean bill oh health by a machinest with 40 years of experience, but that dont mean he didnt overlook something. a cracked head has been in my mind also but id like to see if i overlooked something else myself before removeing the heads. the passenger side exhaust has a miss for about the first minute or so when the engine is cold, the drivers side has a much worse miss for about 4 minutes and as the engine gets hotter it seems to get better but never goes away completely. i have noticed that both exhaust pipes has a little water that comes from them on cold start ups(condinsation i thought) but the drivers side does give off about twice as much. it does not run hot, get water in oil or anything like that. i placed some uv dye in radiator to see if water was leaking through engine somehow, it showed nothing. plugs were ac cr43ts then changed to autolite25 then changed again with another new set of ac cr43ts. wires were bought at orielly auto and then replaced with a nice set of summitt receing wires($80.00) all had no effect on the way it runs..... p/s...thanks for trying to help me

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • Jsdirt
      Gas Prices

      By Jsdirt · Posted

      He does, actually. In another unrelated video he mentions the president called him in the middle of the night to relay some information on a cause (religious based) that he's invested in. Glenn expressed concern that another leftist administration could wield too much power with some procedure the Pentagon was using, classifying certain religions a certain way. Being that he is LDS (Latter Day Saints), he gets hate all the time from ALL over the political spectrum, so he's invested in this. Trump called him back at 5AM to tell him he had made some changes to that classification.   So, yes, they are and have been in contact regularly since the start of the administration. Glenn, of course, always asks his permission before discussing anything on the air.   I already spent an hour or more just searching for these videos. I may have my numbers wrong - I'm not a numbers guy. It may have been a MILLION barrels, not 1.5. The point is, our President, by his actions, gives a crap about America, and US - this is completely OPPOSITE the actions of the prior administration who projected hatred for anyone who wasn't following the left's edicts in lock-step.   Remember, they called January 6th an "Insurrection", when there were ZERO weapons among the crowd, undercover FBI agents agitating the crowd, along with paid leftists acting as aggressors, egging the crowd on in an attempt to whip everyone into a frenzy. It's all been proven.  Pelosi refused Trumps request for more National Guard troops. This smells 100% like an inside job for those with critical thinking skills. Only a handful of guys in the crowd got wrapped up in that, thankfully, but EVERYONE was searched out based on cell phone data, and charges were brought against many. And 6 or so people were locked up and left in solitary confinement for YEARS with ZERO due process!! If you give the slightest crap about our Nation, REGARDLESS of your political leanings, this should frighten you to your core. This is what men suffered, bled, fought, and died against 250 years ago!   This has gone FAR BEYOND left vs. right. This is a  threat to America, and our way of life. This is PRECISELY why Trump, a BILLIONAIRE who could have chosen to take Melania and sit on some tropical island that he could afford to buy himself and RELAX, instead chose to run for office, get hate from literally every corner of the media, get ATTEMPTS on his LIFE constantly, and begin to repair some of the severe damage that's been done to this Great Nation.   I don't know why I bother wasting my precious time here. Everyone has their minds made up. They won't realize we all were correct until it's too late ... after they elect another tyrant that hates America to office (Obama), or another puppet whose administration is secretly running the show behind the scenes (Biden).
    • Newduramaxh*ar
      DTC P2C48 auxiliary cooling pump

      By Newduramaxh*ar · Posted

      Hello, Im in a bit of a bind maybe someone could help me out.  We towed our trailer, up a pretty steep incline (395 north of Bishop) done it before no issues. I got to our campground turn truck off, i restarted the truck about an hour later  and check engine light turns on. Found DTC P2C48,  unable to reset.  This morning i removed the plug, there's 12.12v at the plug. Reservoir near firewall is full of coolant, checked for leaks nothing. I dont hear or feel the pump turning on. My dilemma, is nearest dealer  is 4hrs away that has the pump instock. Is it safe to drive? By me checking the available voltage at the connector and not hearing/feeling pump turn on, is it a bad pump? Please help...
    • KARNUT
      Gas Prices

      By KARNUT · Posted

    • Atlas
      Gas Prices

      By Atlas · Posted

      The figure bandied about is "100 million barrels" so I think a decimal is off somewhere. But that doesn't change the outcome much when the expected flow through the Strait through over the same time should have been more than 2,000,000,000.   So 5%, if that number is even true, and there's sufficient data to believe it's not. Give that man another Fifa peace prize! 5% is less than the flow of a grapefruit-sized prostate blocking the release of cheap lager after a night of bingo.
    • Grumpy Bear
      Gas Prices

      By Grumpy Bear · Posted

      1,500,000 barrels of oil would run a Class 1 refinery for about 3 days.    You guys are deep into where the ants on the boat came from as the Titanic is sinking.    😏

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...