98 K2500 miss at idle?

[hannah09marie]

My 1998 K2500 pickup with a vortec 7.4 litre has a miss only when engine is warm and at an idle. The fuel pressure holds steady @ about 52 to 54 P.S.I. I replaced the cap, rotor, amd plugs. The engine runs good when driving and only misses at an idle. Do you have any suggestions?

[tblake]

Welcome to the club.....

Sounds like a fuel injection issue to me. I am not sure if the 454 has a spider injector and poppet nozzles like the 350, but if it does, My money is on a sticking injector.

[SizeMatters]

Check Plug Wires, The Smallllllllet crack in them bad boys will do this exaccct thing.

[zia-czon]

Also, be sure to check the egr valve for excessive carbon buildup which causes the pintle to stick open, giving you a miss at idle and not noticeable at higher rpms.

[Chevy-SS]

I would recommend a heavy dose of good-quality fuel injector cleaner.

On my K1500, I have had lots of trouble with ignition wires - they cross-fire often. I ended up getting new wires, and then I even went so far as to remove most of the wires from the holders, and I manually positioned the wires to be as far away from each other as possible. You can see how GM solved this issue, as all new engines have separate coilpacks for each cylinder, with one short wire.

Another easy thing to try is to clean the MAF sensor. Get a can of dedicated MAF sensor cleaner from the auto store, then take the MAF out (it's in the plastic air intake housing), then spray clean per directions on can. Be sure to re-install the MAF in the correct orientation. Very easy to do.

Keep us posted.

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