Jump to content

7.4 missfire help

ScottL5385

Recommended Posts

ScottL5385 Enthusiast

ScottL5385

Posted
Posted

I have a 2000 k3500 dump with a 7.4L Auto

Has not been running properly since i purchased.
When first bought, it would begin to accelerate, then hesitate. If throttle was pushed harder it would take off and run great.

Upon purchase the egr was blocked and was showing a maf code.
Unblocked egr, cleared code and came back. Replaced egr, and code went away. Installed a new maf and upon installing maf i noticed a bad connection with the wiring harness to the maf and spliced in a replacement, code went away. also did pcv valve, iac, throttle position sensor.

Truck was running better but still had the hesitation. I replaced the pcv valve, iac, tps and still didnt work correctly. After checking many connectors i found the map sensor was cracked at the intake and only held on by the tab.
Replaced map sensor, and the truck now was running good.

FF a few uses, and now the truck is hesitating/missfiring multiple cyl, mostly 1 but also few on, 2, 3, and 8 again but only after going open loop at 180 and hard to start after warm.

Read many places saying check fuel pressure, found that it dropped to around 40. replaced fuel pressure regulator and injectors. now pressure is 58 initially while cycling key on and off 52 after key is in the on or off position.
This solved my hot start issue.

Next I replaced the complete distributor, wires, and plugs did not help.

Still having trouble with the hesitation it is around 1500 rpm and only while going pretty slow forward or reverse in the yard/driveway

truck has a fairly new exhaust also including highflow cats from previous owner and magnaflow muffler that i did to replace glasspacks.

Can anyone give a direction to look

 

Archived

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

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.6k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    343,007
    Total Members
    8,960
    Most Online
    Brendan C
    Newest Member
    Brendan C
    Joined

  • Who's Online   2 Members, 0 Anonymous, 1,044 Guests (See full list)

  • Latest Articles

  • Posts

    • Grumpy Bear
      Joke Thread

      By Grumpy Bear · Posted

    • Grumpy Bear
      The Peckish Synapse

      By Grumpy Bear · Posted

      You're better read than that Atlas. 😏   British science fiction writer Arthur C. Clarke formulated three adages that are known as Clarke's three laws, of which the third law – that "any sufficiently advanced technology is indistinguishable from magic" – is the best known and most widely cited.   Stribeck and the pivotable Hersey Number isn't voodoo nor snake oil. That part is physics. It's what marketing and bean counters do with it that is snake oil and voodoo.    Stribeck is the relationship between Hersey and the Coefficient of Friction. Within the Hersey Equation if viscosity and viscosity is 'Dependent' on.......heat.......and.......viscosity index or the temperature to viscosity slope.    Specifically Hersey is the viscosity AT THE TEMPERATURE IN THAT LOCATION FOR THAT SLOPE.   Hydrodynamic lubrication exist when the film thickness in the location is 3X the Ra roughness of the surface. This is irrespective of the hardness of the substrate. To obtain that thickness X viscosity is required for Y velocity at Z load. That's a lot of moving parts. It is also impossible to maintain in an ICE but nearly possible with a turbine under constant load.    What does that mean? Error heavy and operate light. Wear is inevitable but the rate of wear and the milage obtainable are a function of prevailing conditions and HABITS. The only penalty is viscous drag and at fractions so low as to be well worth the effort. Double the life, half the manufacturing carbon foot print. Greed is the only impediment.    The materials generated by SwRI are the RESULT not an estimation or a hypothesis.    Don't delude yourself sir, EV's have as many pitfalls as ICE's. We just don't know what they are yet and it will take longer to sort as MARKETING and GREEDY CEO's have had more time to polish the turd they are selling. 
    • Grumpy Bear
      The Peckish Synapse

      By Grumpy Bear · Posted

      You can always count on greed to prey on ignorance and stupidity.    Friend bought a 2019 Ford Flex and asked me about using Valvoline R&P 5W30 in it. Told him give the miles on it and the fact it wasn't yet using oil that it was a good plan. He uses a Valvoline quick change shop for his oil service.   First they tell him that isn't the oil the OEM recommends. He told them he didn't care what the OEM thought. Then they floated the, "But it will void your warranty"    His reply was it's a 2019, there is no warranty and informed them their knowledge of the law was lacking.    Then they tell him 'But it will ruin your motor"!.    Mine to ruin he says. Finally they give in and charge him 150% the semi-syn price    Point it the brainwash is so embedded that even the service industry is drunk on their swill. The public is right behind them. Echoing the same lies on every forum and media platform. If the end goal is indeed EV then I'd say that ship is about built. 
    • CamGTP
      Gas Prices

      By CamGTP · Posted

      Diesel hit $6.00 here today at the truck stop.   Payed $2.79 for E85 today too.
    • richard wysong
      Electrical Problem - solved

      By richard wysong · Posted

      Thanks for posting, I'm sure it will help someone

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...