1994Vmax

iTrader: (4)

So for about at least 2 years my 2005 GMC listed below has had the torque converter unlock at random and refuse to lock again. A lot of guys immediately blame the converter.. or the apply solenoid as the source and leave it there. I am lazy in the sense I just left it.... to hell with it haha. So tonight I datalog and what do I find.......

Although others do contribute I get misfires mostly on cylinders 1 and 6 which then in turn toggle the bit that forces the converter to stay unlocked due to misfire...... Oh joy.

Now...... I have MSD plug wires as well as stock replacement Delco iridium plugs that I put in about 2 years ago...... How much money says when I pull the MSD wires and replace them with the oem stock ones that came on my LS3 crate all this goes away...... haha.

For clarity and just cause, no my CEL has never once came on for misfire nor are there any codes. It starts really doing it the faster you go with it locked..... but wide open throttle or even with the converter unlocked most of the misfires go away completely to the point the counter stay pretty much at zero. I will start simple anyway and move up the chain if need be..... I think it's funny if it's just the damn plug wires lol.

Wolftrk99

iTrader: (5)

1 and 6 are companion cylinders.... So one may be affecting the other if you have carbon build up or whatever causing detonation on the opposite cylinder.... Id pull the plugs just for sng's to see what they look like... Most misfires go away at higher rpms, at least that i have noticed, usually because the ecm is looking for crank speed variation on the cylinder and if its not above a certain threshold wont throw a cel, the next step is a dtc with a light, then if its severe enough to damage the cats it will throw a code and the cel will flash.... Probably more info than you needed or wanted but....

1994Vmax

iTrader: (4)

Meh lol. It could be more.... but I have my doubts. I am pulling the plugs.... maybe I cracked one for all I know but it's a pretty solid idea I didn't. This truck gets the ever living **** driven out of it and I have had the issue for at least 50000 or 60000 miles so I doubt carbon is much of an issue in it. The only time it does it is like 80 mph with converter locked.... otherwise basically nothing. Cylinder 8 pings in too so it's not just isolated to 1 and 6 but it's mostly those 2. Very sporadic too.... not constant by any stretch.... spikes and then does nothing for a minute or more. Even lower speeds loaded it doesn't misfire....... and I know it has less issues with a trailer behind it...... goes almost back to perfect. It could be something weird and if it is... well.... it can do it forever for all I really care...... Not like I really cared enough to do anything in 2 years already lol. The mileage really is absolutely no better one way or the other. I could plop the old LQ9 in it if it actually gets bad enough..... but I doubt it will.

Wolftrk99

iTrader: (5)

Missed that it only does it at higher rpms somehow... Be curious if wires fix it or not!!! Weak injector maybe?

1994Vmax

iTrader: (4)

Higher speeds not rpm. It doesn't do it at WOT that I noticed ever. If i am doing 70 or 80 mph crusing it starts getting worse and then forces it to unlock. But do 70 mph with 6000 lbs in tow..... locks up constantly..... haha. I have had terrible luck with MSD anything in the past.... it really would not surprise me anymore lol. Maybe it's my shoddy tuning...... not likely as it's never done it before and it has been tuned for about 5 years now.

I am just going on the KISS principle for now..... I did plugs and wires sometime around when I remember this stuff starting. And here I was going to toss a Circle D 3000 stall in it... well.... I probably still will lol.

If this fixes it... well it reminds me of a guy on a forum that had the exact symptoms I did.... would unlock and then under load like with a trailer was fine. He changed everything on that truck.... torque converter, apply solenoid, valve body and shift kit, MAF, MAP, TPS, etc. Kept throwing parts at it with different shops along the way.... never changed. He got mad and sold it lol..... I remember reading that and just saying screw it lol.

1994Vmax

iTrader: (4)

Well I figured it out and the fix could be done by leaving the hood closed and in about a minute or less of time.

I went ahead and initially pulled plugs 1 and 6.... now they were a touch loose for my liking and the gap was way too wide at like 60 thou plus. So I regapped them to 45 thou and installed GM oem wires on those 2 cylinders. Took it for a drive and honestly it might have been even worse than before...... so much for that idea.

So I went ahead and started googling my issue and I found it! Multiple people have the same problem and say to perform a Crank relearn on the truck to cure it. So I fired up HP and went out and did the relearn.... voila.... no more misfires on any cylinders. Another benefit is the truck runs smoother and it seems to have the power it used to have back again..... So if anyone else is fighting stupid misfires perform a crank relearn first before you start changing parts......

I am going to regap and retorque all my spark plugs though haha

hourang

iTrader: (6)

nice you figured it out! just a bit of my experience with MSD wires. my camaro ran perfect, installed a 150shot nitrous kit and could not figure out why it was breaking up when i hit the nitrous. Turns out it was the wires, fresh set of ac delco's and no hesitation/misfires. wires had maybe 5k miles on them, i seriously tore every part of the nitrous system apart trying to figure that out.

1994Vmax

iTrader: (4)

These still seem alright so I will keep running them. I did put new plugs in... These old ones were burned down pretty good hence the gap increase. Now I will go for a drive and see what it's like to have working torque converter lockup lol.