Vortec 7.4 rough idle

Discussion in 'The Garage' started by Seannn92, Mar 19, 2020.

  1. Supercharged111

    Supercharged111 I'm Awesome

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    I see a couple moist plugs, but in my dictionary a fouled plug doesn't fire so you'll need to elaborate there.
     
  2. Seannn92

    Seannn92 Newbie

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    Plugs look like sh$t. Plus most were finger tight. If not the problem I’m having it would certainly become a future problem.
     
  3. Supercharged111

    Supercharged111 I'm Awesome

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    Looks like shjt =/= fouled. They may need replacement, but if they're firing they're not fouled. Dig deeper, if the PO was ignorant enough to leave the plugs loose the sky is the limit on the rest of the truck.
     
  4. Seannn92

    Seannn92 Newbie

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    It idled okay before the distributor gear broke so I’m still thinking the distributor is still off. But I’ve reinstalled it probably 20 times and it only wants run in one position. One tooth either way and it doesn’t run or barely runs. I doubt I’m 180 degrees out as it wouldn’t run at all. Is there a trick to installing the distributor on a 454? For example, the plenum limits play a lot more than the small blocks.
     
  5. Supercharged111

    Supercharged111 I'm Awesome

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    For me just had to have it on the right tooth. When my gear was worn on my 350, there was no tooth that would get me in spec. Could be a mismatch with the gear clocked differently to the pin hole?
     
  6. Seannn92

    Seannn92 Newbie

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    And what about my FPR? Truck has always been hard starting. I replaced injectors, filter, FPR and pump recently trying to solve this issue. Fuel pressure drops immediately after key is turned off. When I clamped return line the pressure stayed without any drop off so it must be losing pressure at the return line which means FPR not holding? Also pressure increased by about 8 lbs when vacuum line was removed. Specs say 12-14 is what it should be.
     
  7. Seannn92

    Seannn92 Newbie

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    Possibly, how’d you get it in spec then?
     
  8. Supercharged111

    Supercharged111 I'm Awesome

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    Sounds like for is bleeding down. Mine only changes around 4psi when I unplug it. I got the 350 back in spec with a new gear, but it was a factory gear on a factory housing. I think if you remove the gear and spin it 180 it'll change its clocking as well.
     
  9. Seannn92

    Seannn92 Newbie

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    I’m going to replace the fpr. I compared the gear with the old one they are exactly the same. Dipple side is between two teeth and the pin hole on the non dimple side is on a tooth.
     
  10. Seannn92

    Seannn92 Newbie

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    Some good news... after changing the plugs, wires and FPR it’s idling good now. I took advantage of the plenum being off to restab the distributor without all the tweaks and turns you have to go through to get it in when the plenum is in the way on the 454. Crazy thing is that it took awhile to finally start. Backfired a couple of times and then it finally ran. A few days ago I would’ve given up and pulled the distributor out after a few no start cranks. But this time I was pretty positive I was in right cause of how meticulous I was putting it in. I have the p1345 code so I still need to set the cam retard, maybe I’m still off a tooth dunno but I can live with that as long as it doesn’t give me whiplash in gear!
     
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