Canadian Hummer Club Forums

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So here's the story,



Yesterday I drove to my friends,about 70KMs from my place, finished installing the overhead and grillelights, with Jay's advice. While we were doing the wiring, i decided toalso change the plugs and wires for the new ones I bought, NGK Plugsand Taylor thunder Volts wires, I decided to start on Cylinder 7 as itlooked tough at the back and pointed towards the truck, after screwingaround with it and not being able to get to it other then from insidethe wheel well, I had my buddy help with lots of extensions and a 1/2ratchet, we tried to loosen the plug, it wasn't going anywhere, so Isaid screw this, I just changed the wires, finished the wires and I wason my way home, lights all working great and new wires on, plugs Ifigured i would have the dealer deal with later. Anyways as I wasdriving home, the truck started to misfire and the check engine lightkept flashing, the truck was running like crap.

So when I gothome i first checked all the wires, maybe I had not put them on tight,not sure, but they were all good, so i changed them back to factory ACdelco ones, that I had took off earlier, still no good, now checkengine light on constant.

Getting p1$$ed i called it a night andsaid I will let dealer figure it out! I took it in to the dealer,Queensway in Toronto, at 7:30am est and now it is 9:00pm est and Istill have no truck and they have no Idea. They tried to tell me it wasto do with my after market compustar remote starer and how it wasinstalled. They said this but I have had the starter for over a fewmonths now without issue, I am sure it has to do with the plug but theyare saying that maybe the starter screwed the ECM because of the way itwas wired, I have no clue but that sounds fishy!

So anyways thecheck engine lights reads as misfire in cylinder 7 and 8, they say theychecked the wires and swapped them around but no change, they did acompression test on cylinder 8 and it passed but cylinder seven was toolate as they need to lift the truck up to test. They have no tried toflash computer mem or anything else, the mechanic is stuck on thisbeing the starter caused it and saying that it may have screwed the ecmsomehow.



Anyone ever hear of this or do you all think thatit maybe still be that damn plug we may have tried to get out, maybe wecracked it? Would that impact the cylinder 8 too??

bump

This should most likely be as aresult of a crack to the plug. As a GM Technician and Hummer Tech, I would not say that the remote starter caused the problem unless I could prove it beyond the shadow of a doubt. A Tech II scanner will be able to tell exactly what is going on for those misfires, it could even be loose or dirty connections to your coils, this happens often especially after washing the engine. It is very surprising that the plugs should be that jammed in there, how much mileage do you have? Also due to the aluminum heads you should only try to remove plugs when the engine is cold, to prevent stripping the threads in the heads. There is a possibility that someone at sometime has pulled that plug before and cross threaded it when putting it back in and that would make sense as to why you are having tremendous difficulty removing it. For cylinder #8 also misfriring, due to its location just pulling off the wire or installing it could crack the plug and cause a misfire. Start will the plugs and wires...your problem is most likely there not with your ECM or Remote starter. If remote starters are wired wrong they normally toast things pretty quick not after months of use.<DIV> </DIV><DIV>Kevin</DIV>

resolved, thanks, it was plugs and wires, a cracked plug