• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

04 gtp cylinder #3 missfire

his code reader did say random missfire i do remember him sayin that.. We did take all wires off and put them back on when we were checking the spark the little tool my dad has that you hook in the wire between either the coil and wire or wire and plug, all showed good. I and a couple other ppl around here think that might be electric problem, because we have noticed while lookin at it the last couple days that seems like all the wiring has been tampered with all is exposed, or has electrical tape on it, which obviously isnt normal. The plugs and wires seem to be firing totally fine according to that tool. Coils are nice and clean, and sending good spark. so were gonna go through some of the wiring on it and see if its shorting somewhere maybe injector wires, or who knows. They are all exposed and hitting metal stuff that could be shorting it or somethin. wiring is just a total mess under there, have looked at it many times just never noticed how messed up it looks. So i will keep in touch. Ne more ideas are welcome, bc the jack arses around here that charge the big bucks cant do it. I will do what i can get done with the last few suggestions b4 the wknd , bc sat. its oing in and isnt leavin till its runnin like its supposed to.....
 


most common thing other then needing a tune up is a clogged cat. it can also cause random misfires, and make the cel light flash.
 
I have no lights and no codes other than random missfire. never had a light go on yet which is kinda wierd. Talked with a mechanic today, and he thought maybe map sensor?? I found a mechanic that is willing to come to my house and hes gonna check it all over move things around, and check ecm, map sensor, and all that stuff. So hopefully it will get found this wknd.. :)
 
Well the mechanic came over today, and got somewhat of good news. It didnt miss a beat the whole time he was testing it. Started and shut it off several times, and no misses at all. It did have another code in it now though, said cyl.3 injector electric miss or somethin like that dont remember exact words. But he said that means that the injector isnt getting the signal to go off every time, also was for #4. So therefore hopefully if that is correct, its nothing serious,just possibly the pcm he said. And so far today its all good. he checked the voltage going into it and was good. He also checked the negative polarity on it and that was good so he has it narrowed down to the pcm, but he said to just leave it till it acts up agin and have him plug it in and check to see. So now at least that its runnin fine i no its not internal!! The popping i had comin out of the exhaust he said could be anything bad muffler, baffles loose, a couple other things. I could see the engine wasnt bouncin around like it has beenit was just sittin there nice and smooth. So does anyone have a though on it now? Think its a pcm??
 
bad injectors maybe. if you unplug the injector, then take the small marker bulb out of the headlight, you can plug the bulb into the injector plug, harness side of course. then go start the car, the bulb should flash if its getting power to it. if its got power, chances are the injectors need to be cleaned or replaced.
 


its a brand new injector in there though. It said that the injector wasnt being sent the signal basically. I wish i could remember word for word what the code said. but the mechanic said that it meant that it wasnt being told to send the fuel basically the injector checked out good he checked the negative polarity on it and it was good, but its a random missfire, and today it was fine the whole time i was drivin it and while we were tryin to make it miss. So he thinks its a pcm going bad slowly, but my only worry is that only 3 and 4 showed missing in the history absolutley none on ne other cyl.
 
Ok just found out that the #3 injector that i replaced was infact junk also. so not sure what the deal is seems like the electronics in this thing are takin a crap. it is still missing sometimes. Think im just gonna go get a pcm from the junk yard its 20 bucks and i can get it flashed for free. Otherwise i found a refurbished and reprogrammed one for 130 bucks. Is that the way to go? that way i know it works good. Its reprogrammed to change a bunch of things and more power, says gives it more gas in troubled areas, i dont remember all the stuff, but im sure you guys know what they usually do. Is that a better way to go? What size pulley comes on the 04 gtp stock? Says it has to have 1 of two sizes in order to have this pcm and a cold air intake which i have now.
 
stock is a 3.8

to run ANYTHING smaller you need intake, headers, tune at the very least.

Doubt its your PCM through. Why dont you listen to the above suggestions and test the connection with a light bulb?
 
Everything that has ever been suggested here has been done.. Everything checks out just fine.. we are down to the pcm. the computer said something to the affect of injector#3 missfire.. which means its either the injector, wiring, or pcm. Ijector is fine,has been tested.. Wiring is fine has been gone through.. So all thats left is the pcm.. I'm not sayin thats the prob, the mechanic that came over and did the work narrowed it down to it, i gave up guessing on this thing a long time ago. Its rediculus. I dont understand how this can be so hard to firgure out. the computer also showed in the last 70 key cycles that cyl #3 missed 187 time, and cyl #4 missed 87 times rest were at 0. So for 20 bucks im gonna go yank a pcm from junk yard and try it, it will be the cheapest waste of money i have done so far to this thing.. Any other suggestions are welcome though please!!!!
 
ok get this. This morning when I went to leave for work, I started my car (that's kept in the garage) and it idled like an old john deere tractor ( not sure if you all know how they ran, two cyl engines sounded very rough and shook the whole tractor) well that's how my car was runnin at idle. I was literally sitting in my car bouncing in the seat. I could hear it spittin and spudderin. I gave it some gas about 3,500 rpm, and let it go back to idle, ran perfect from then on. Talked to 2 more ppl today, and they said icm, and map sensor. Im temted to put in the rebuiltand reprogrammed pcm, and icm and a map sensor, and that should cover pretty much all electronics. Went on a diff site for gp's tonight, and just read a couple diff posts, sounds like this is somewhat of a common prob with these... the missing thing. and everyone is a little diff, and they all have probs figuring it out, and all diff solutions.
 


PCM? that's what runs the injectors right? the injectors are whats not workin right. Im looking for one, but they are almost the same price as a rebuilt and reprogrammed one, so i think that what im gonna do. It's 125 bucks for that, and one yard i called today wanted 125 for one out of a junker so prob go that route and get a rebuilt one. I will go and see the website and put it on here for you to look at if you would and let me know what you think of it?? I called bergstrom today and finally talked with someone that knew something about cars. I told him what has been going on and what has all been done and checked, and without hesitation he said your PCM is going bad. the first mechanic that i have talked to around here that actually didn't act like i was speaking some foreign language to him..
 
Just talked to the owner of that company, and told him whats been going on and whats been done. He said that it deff. sounds like a bad pcm. So I ordered it. Says gives at least 20 horse, plus all the other changes. Guess it changes your shifting kinda like a shift kit makes it slam into gear a little harder instead of slowly sliding into gear which is better for the tranny. Theres a whole list of things it changes. Hopefully this is the end of the issues for a long time now!!
 
well I got my reprogrammed pcm tonight. So in the morning i'm gonna be takin a ride to test things the way they are now, and then again after I switch them out. Going to check speed ina certain distance, and time. Also gonna check gas mileage. and hopefully I wont have a misfire anymore! I keep plugging it into my neighbors computer and it keeps jumping around sayin 3 and 5 then 3 and 4 and so on but its all injector issues so obviously it should be computer if an injector is bad its bad. This is supposed to help mileage a little, and they said 20 plus horse.. So hopefully it all works out for me. I will let ya all know..
 


well I put it in and so far no misfires, but haven't run it much sometimes it went for days without a misfire. But I did some tests on it as far as speed and time. I gained 11 mph. But the thing that kinda confuses me is that the time stayed pretty much exactly the same, not sure how that's possible?? I do not know the distance just went from one point in the road to another, guess I could have been off on my pressing the button on stopwatch also. It does shift a little harder when under full load, also shifts at higher rpm when under full load. It seems like it just runs a lot smoother and better.. But i'm gonna have to run it a few days to know for sure if my miss is gone.. FINGERS CROSSED!!
 
the trans shifting hard could just be the pcm and tranny learning. can take a day to smooth out.

sounds good so far. hope this is the fix once and for all.
 
I don't even wanna say shifting hard. Its just a cleaner shift doesn't really slide in like stock, just that when it shifts it does it now.. Its def a way better feeling of a shift put it that way. but cant figure out how I can run 10-11 mph faster, but still have the same time? Like I said not sayin I pushed the stop or go button on stopwatch perfect, but that's tenths of a second. I would think it would be a second or more quicker with that much speed gain??
 
Speed doesnt always mean a faster time.

But I wouldn't count on a stop watch for a correct reading as there are too many variables.

Then also figure in that your car was not in the best shape before you started installing all these new parts and the PCM.
 
You must log in or register to reply here.
Back
Top