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I'm having some serious problems with my truck.

It started out as rough idling and then it got worse. I have replaced all 4 O2 sensors, temperature sensor, knock sensor, distributor wires, distributor and cylinder 5 spark plug. It hasn't changed at all and still runs like crap. I've replaced cylinder 5 spark plug twice now. The electrode was burnt and the porcelain broke both times. Theres a bad knocking/pinging sound going on too.

The truck also wants to try to reach 260 on the temperature gauge. There's air in the cooling system and I don't know how to bleed it.

Also, I looked up how to test the EGR valve but it only showed symptoms of a bad EGR valve. My truck has all of them. But before I replace it I want to test it with a vacuum pump.

Can anyone tell me what else could be the problem? I've already spent $500 on parts. My list of problems was: catalytic convertors, EGR valve, computer, O2 sensors, monitors, 2 Inc, and other.

Help would be much appreciated. Thank you

Skyler.kay
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2 Answers2

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I see the following possibilities:

  • Like dlu said: wrong range of spark plugs. Perhaps you can try some colder ones. When trying this: be sure to check the spark plugs soon, a too cold spark plug tends to get soot buildup.
  • Engine running lean. Is there a matching trouble code stored?
    • Try to run the engine with disconnected maf sensor. Should things get better: replace the maf sensor.
    • Test for vacuum leaks. While idling spray gently some flammable aerosol (brake cleaner, start pilot, deodorant, wifes chanel no. 5) around the intake tube/manifold, starting from the maf sensor. If the engine sound changes there is a vacuum leak on this part of the intake.

Attention: I would recommend to correct this issue soon. This type of malfunction could, under circumstances, melt a hole in the pistons

Your newest comment was enlighting: find out if some distributor cables got plugged in in the wrong order

Martin
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My first thought here is to tackle the problems methodically, one at a time.

The one that sounds most significant to me is the plug 5 damage – from what you've said it sounds like detonation (aka pinging, due to premature ignition), but I would also double check that the spark plugs are the correct ones, it could be that you've got plugs in there with a reach that is just slightly too long and that you're seeing mechanical damage.

I suppose the cooling problem and the detonation could be linked, especially if air in the system gathers around cylinder 5. I did a search on

chevy silverado 5.7 bleed cooling system

and found some promising looking links – but I don't have any experience with Chevys so I can't say if any of them are right in the details.

Finally, check out the EGR and see if both the valve and its control system seem to be operating correctly.

My take from your list of potential other problems is that it is a "shotgun list" and that you'd do better to tackle the known problems first so that you can be confident that they are out of the way.

dlu
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