Hey all, i just put a set of pacesetter lt's and ory ony my truck last week, while i was at it i put in a set of ngk tr55 plugs. Well i was running it with my stock pcm while wheatley was retuning it for the headers and this thing was running like @$$. It was missing a little at idle and when you give it gas, usually not while at WOT. I thought it would clear up with the other pcm which it did, for about 75 miles then it slowly came back. Ive checked everything i can think of, coil plugs, new wires, injector plugs, made sure wires were on tight, ive always ran a can of sea foam at every oil change so the fuel system should be clean, im about to run this thing into a tree im so frustrated, ive tried all week. Also i am getting codes 0300- random misfire, 0141-61 rear 02 heater circuit, which i thought charlie would tune out but he must of forgot. ANY IDEAS??? P.S. sorry for the longwindedness!! Thanks!

 

I can tell what happened to me when I had the misfire...it turns out the #7 wire was getting toasted by the new headers, so I changed all of the wires out and found these wire insulators that cover up to 1200 degrees. Since then never had a problem.
http://cableorganizer.com/insultherm-spark/


Lisa

 

did you drop a spark plug when you were changing them out? if you drop one and it cracks, you'll have these problems as well...

 

I changed the wires after the headers were done, about 100 miles thinking i broke a wire during the install, same problem instantly. When i put charlies tune back in yesterday it ran great for about 75-100 miles then it progressively came back???? And thanks for the help!!

 

O and don't ask why but today i added about 4 gallons of 110 to 3/4 tank and after about a mile or so it got better and now running perfect?? sure not spending $5 a gallon to drive my DD. Cant figure what the 110 would do besides if there was too much timing, its a stock motor. EDIT running like @$$ once again... Im at wits end im gonna try replacing the tr55 with some new stock ac iridiums. Its a random mis, code 0300 its not cylinder specific.

 

maybe wheatley tuned it for 93 instead of 91? Idk that seams like too much of a rookie mistake for him...

 

what is the gap at on the plug? are there any exhaust leaks around where the heads and headers meet? do you have any way to data log? a exhaust leak could make your o2's think they are lean and add to much fuel. just some ideas to think about.

 

Well problem solved. It seems my truck did not like the tr55's too well, i have heard to gap them anywhere between 35-60 thou so i had them at .050. I swapped them out for some new oe ac iridiums, and it purrs like a kitten now, no misfires whatsoever. Those of you running tr55's, what are you gapping them at, and why do you choose them over the acdelco's? Thanks for the replies i know i am somewhat new on here but i try to help if i can.

 

I have had problems with the ngk's Also now I just use AC Delco double platniums

 

Great to see you found the problem.