Tough trouble

[Jsdirt]

NGK's are cheaper. Same exact plug too.

[sdog4127]

IAC in my opinion should never cause a misfire or poor idle issue unless it is holding idle below desired RPM. I wouldn't just throw parts at it at this point. Need to know facts of what is happening (easier said than done, I know!!!). As far as aftermarket spark plugs... I am a huge proponent of using factory parts. Give it what it was born with, that is how it was engineered and designed to run optimal in all applications. I would not recommend paying the price for E3 or any "performance" spark plug as you are just changing the variables further.

I haven't offered any real advice to remedy your situation, but I would stick to GM only parts until you iron this problem out.

 

great luck!!!!

[Blueballs]

I have been following performance magazines and I'm an ex certified mechanic. Use AC Delco plugs exactly what came I. The truck. The only time they should be changed to something different is if you are adding nitrous, a supercharger, a turbocharger, or decking the heads to I crease compression. Otherwise, the stick plugs made by the manufacturer that they came from the factory with will always perform the best.

 

It has been proven many times having more electrodes to have spark jump the gap to doesn't help. Even with MSD it will only fire to one electrode at a time so the others are useless until the others burn out. Save your money and go with AC Delco!!

[r2142]

So it has been a bit since I did anything else to the truck but I learned something by accident. I started the truck and pulled the battery terminal and the truck died instantly so I had the alternator tested. It tested good but the battery did not pass. Seems the alternator was sending most of the energy to charge the 7 year old battery and soon as I replaced the battery the truck started running better. It still has a slight miss after running a few minutes but it has more power and runs smoother than it has in quite some time. I wonder if I need to replace the ignition control module since it is echlin POS

[r2142]

Has anyone ever tried diagnosing the harness? Is there a pin-out for the ECU that I could maybe look for a short or a ground? I really think with all the parts that I have changed that something is wrong with the wire harness.

[Jsdirt]

Yikes man .... don't EVER yank a battery terminal on anything built after 1995 while it's running! Just asking for trouble. Too many delicate electronics on these things, and you've got enough trouble here!

 

 

Checking the harness is the best way to diagnose this, since you've already replaced parts - check for continuity or voltage at the computer. Check every wire going to the device - need good 5v reference, ground, and signal return. You'll need a good, and CORRECT wiring diagram, or you'll yank all your hair out in frustration. Check for 5v reference on a few different sensors to make sure that's ok. Helps having a scan tool with a graphing feature to check operation if the unit runs on a PWM signal.

 

This type of work makes me nuts. Hope you discover something!