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04 gtp cylinder #3 missfire



If the issue didn't occur until the tune up, maybe you are ok as mentioned. However if a shop was testing the car, they should be able to tell you if it's an injector, coil pack etc. Definately consider somewhere else. Why if Dad is a mechanic is he not looking it over?

As for knock and fuel, that link that was posted is quite important to read and in a forced induction motor you want higher octane to battle predetonation. It's on the fuel tank door, cluster (I think) and the owners manual. Putting the wrong thing in your mouth could result in death, right? Putting the wrong thing in the tank is similar for your charged motor.

Hope it's not a popped piston, but considering how #3 and #4 are the middle pistons that get the hottest, it's more likely that it's a piston than most other stuff.
 
Dad hasnt been up to current vehicles for a while he is more of a tractor and heavy equip mechanic, but is very good with engines he tears them apart on tractors and stuff all the time, but tractor engines and vehicles do vary a little. So he does usually have a good idea as to what it is, sometimes he is a little off. Not sure if it happened after the tune up or not, didnt notice it until couple wks after. Its hard to notice just listening to it, but now that i know its there i hear it all the time.. Also it seems like its just at idol, but not sure. When i do get on it when i pull out to pass, or if i just step on it for the heck of it, it sure doesnt seem like it has a miss as hard as that thing pulls.
 
Ok i was supposed to take my car in today to get the missfire figured out, but got called into work, so had to put it off another wk so i will be in touch with hopefully some answers nxt monday..
 
this is my 3rd gtp and never ran high octane gas and never had this prob.
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AAAAAAAAAAAAAAAHHHHHHHHHHHHHHH.....

I fear the last two you had are bought by someone else that wants a reliable car.

1. If you use regular gas, and go WOT on boosted car, your piston goes BANG...and that makes the plug tip look pretty nasty. Pull plug and evaluate. 5 mins and a 3/8" wratchet and 5/8" plug socket.
2. If mechanic dropped plug, then just stuffed it into slot 3, you have a bad gap and misfire. Pull plug and evaluate. 5 mins and a 3/8" wratchet and 5/8" plug socket.
3. If mechanic used stock wires back onto new plugs instead of changing them, wire may be bad from removal process. 10 mins and a new set of wires, or you can move the wire to #1 and see if problem moves there.
4. Move coil pack to see if problem moves. 5 mins using 7/32" socket and 1/4" wratchet and extension.
5. You need new mechanic. Use terminology when looking for one. IE, ask if they have GM L36 or L67 or 3800 experience, not "I have a grand prix". It will keep you from getting a stupid mechanic that don't know a 3800.
6. Take a look at some of the simple items above, and between you and a few of us on the forum, we can narrow this down and put a more focussed fix in your hands to take to the shop. If you have already spent $2k...won't you be real upset if 5 mins of your time and a few posts narrows the problem?
 


Ya i know i have a bad mechanic, which is why i wont take it there ne more. I recently had a clunk in the front right side, i looked at it a little with my neighbor, and we firgured it sounded like it is comin from in the tranny. I took it on for a (professional ) opinion, and they told me i was in the cv shaft 2 change it and all will be good. I said no better look at it again, so i went out in the shop with him and showed him what we found. He looked at stuff on the computer and said no its gotta be the shaft. So i said ok and i changed it, well guess what still got the clunk. Called em and told them and i also threw it in that i would like to be reimbursed the price of the shaft bc it wasn't the prob. They said we didnt do the work so no we cant!! what a bunch of bs.... Ne way the clunk happens w i go from forward to reverse like backing into parking stall when i give it a little gas front right goes bang. doesnt happen w going from reverse to forward, just the other way around. Think its in the tranny but not sure not much else it could be have replaced sway bar links and bushings few months ago. NE ideas?
 
well tomorrow is the big day, i have to take it in at 830 to figure out what the prob is. So my fingers are crossed. Also have noticed that when i start it up in the mornin, when its cold, when it idles high i listen to it and it never misses a beat. Also while drivin when u get on it, it doesnt seem like its missing, i guess the supercharger could cover that up though.. I will be in touch!!
 
Well just got my news. I either have a plugged or bad injector, prob thanks to the dumb mechanics that did the flush at the other dealer since thats when it started. Also the clunk i have in the front right side is in the tranny which is what i thought just like my 03. They said some sun gear or somethin in there, not real sure after he said it would have to come out and either get rebuilt or replaced i kinda zoned out on the rest of it. So anyone got some advice on that or ideas on it, was thinkin of leavin it till it got worse and thenjust takin it out and seein what a rebuild would cost versus a diff one???????
 
slgrnvlfire said:
Well just got my news. I either have a plugged or bad injector, prob thanks to the dumb mechanics that did the flush at the other dealer since thats when it started. Also the clunk i have in the front right side is in the tranny which is what i thought just like my 03. They said some sun gear or somethin in there, not real sure after he said it would have to come out and either get rebuilt or replaced i kinda zoned out on the rest of it. So anyone got some advice on that or ideas on it, was thinkin of leavin it till it got worse and thenjust takin it out and seein what a rebuild would cost versus a diff one???????
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I never understand why people get transmission flushes. As a certified mechanic I won't do them on my own cars, I have seen more bad than good come from them
 


the only way id flush a tranny is if i got the car, or the tranny new/rebuilt. then flush it at every 30,000. did that with both my brand new trucks. in my case, that was every year. i drove 30,000 miles a year.

both were work trucks, and plow trucks, so yes the trannys did break sooner or later, both when over 100,000 miles, lets just say i drove them like i stole them.
 
either way it has to come out so im just gonna let it till it gets bad and make a decision then i guess either to rebuild or get a diff one.
 
well more bad news for me!! changed the supposid bad injector, and still is missing, and think its possibly worse than it was before!! this thing is driving me nuts!! and draining my bank account.
 
anyone got any ideas now? I did just realize that they said they swaped the plug andwire around. that only eliminates the plug and the wire, doesnt eliminate the ecm or the coil and they said it does, but to me it doesnt bc its all still runnin the same cylinder. RIGHT? Also another kind of red flag on the coil is that i noticed there is a pink marker hash on that coil like it came from a junk yard or the place i bought it from was tryin to figure somethin out maybe, but thats the only one with a mark on it.
 


swap the coils around, clean the icm where the coils bolt down. you can also have the icm tested or swap it with a junk yard icm for cheap.

junk yard oem parts for the most part are ok, sensors that cost a arm and a leg are reused all the time. im running a used maf from a jy for the last 2.5 years problem free.
 
Another question i have is im looking through all the parts for sale, and wondering what i have for an engine, I know its a 3.8 supercharged, but what is it i see all these L32, L67 and so on what is mine? 04 gtp comp g Then maybe i will know what im lookin at..
 
icm is a ignition control module. nothing to flash, swap it.

04 up, you have a l32 and with a gen 5 blower. 97-03 l67 gen 3.

you may or may not have upgraded lim gaskets, look where the lim meets the head, under the valve cover lip. if you see a black gasket they are plastic and should be changed. if you see silver, you have the upgraded gaskets.
 
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