3800 P0303

[Toasty]

So I limped the gtp to auto zone near work, came away with code P0303 misfire on cyl 3, in computer 2x. I removed each plug wire one at a time and started car each time, to check spark coming from the coils. each seemed OK, but the 1/4 coil, specifically terminal 1 seemed somewhat more eratic/slower rate than the others, more closely matching the engines rough idle. Does anyone here have the ohm resistance values for the coils?

I dunno if i can get to the rear plug without being able to move the motor or not



worst thing is i cant be driving it the 40ish miles back home as it is

Click to read more...

 

[Fish]

Plug 3 is the front middle. Check the connections to make sure they are on tight. If its still a problem, pull that plug and check it out.

Ive had misfires on cylinders before that were caused by a loose plug wire.

 

[Xtant12]

Originally posted by Fish@Jul 12 2006, 11:25 PM
Plug 3 is the front middle. Check the connections to make sure they are on tight. If its still a problem, pull that plug and check it out.

Ive had misfires on cylinders before that were caused by a loose plug wire.

[snapback]132052[/snapback]​

Good stuff... ALSO... This might help.. The dealer told me to take off the metal connectors when they did my first tune up..( That mistake will never happen again...) they said that it causes misfires... if it is true or not I dont know.. But I thought I would add... Might help.. you never know...

 

[Fish]

The metal on the ends of the stock plugs are just heat shields. I dont know why those would cause misfires.

 

[Toasty]

whew... Thanks for pointing that out, I was looking at the diagram from my alldatadiy subscription upside down i guess.


what else besides ignition module, coil, wire and plug would cause the misfire code... other sensor bad? there was no accompanying code for anything else like fuel system (injector, etc)


If the plug looks good, and I try another plug wire, what should I look at next?


on edit, the middle front plug wire doesnt have the heat shield on it anymore, so that cant be a problem.....

my guess as to why the dealer would say they may 'cause' misfires was actually meant that they may assist in creating a misfire condition, if the spark leaks through the boot to the heat shield which could more easily transfer the spark to the block, etc...

 

[Xtant12]

Originally posted by Fish@Jul 12 2006, 11:48 PM
The metal on the ends of the stock plugs are just heat shields. I dont know why those would cause misfires.

[snapback]132057[/snapback]​

im unsure aswell... but that was what they said.. I havent had them on since and I have had no problems...

 

[Fish]

Usually it would be a plug, plug wire, or maybe even a coil. Our stock coils are very good, but they can fail. Im not totally sure what else would cause a misfire if it isnt one of those three components.

Since you said the plug was fine, it could be a loose wire. Or you might need new wires. If that doesnt fix it, look at the coils. IMO that would be the order I would look at it.

 

[Toasty]

on a not so related note, where on the underside of the engine/trans are the motor mounts?

 

[TonzKnock-G]

Ive had stock a stock wire(cyl 3) and coil go bad on my 04.

 

[imported_GraFFix]

I had the same issue it was a bad coil...same cylinder too, not that it makes a difference but its just coincedence

 

[Toasty]

I'm going to pull the plug while at work today and see what shape it is in, hoping for it to not be smashed

 

[Toasty]

YAY! .. well sorta, hahaha!

so i went to pull the #3 plug to check it out.. so i grab onto the spark plug wire boot (NOT just the wire mind you) gave it a little twist to make sure it wasnt stuck to the porcelain, then pulled back, and the metal insert stayed on the plug, letting the boot and wire come off in my hand. It did not look coroded, but that could be a problem! ... anyway, I removed the plug, and it looked in pretty good shape, accept for one thing IT WAS SOAKED WITH FUEL!!! So it is not getting any spark, but the coil seemed to have spark OK, so the wire should be the issue. I also pulled the plug next to it (#5) and it was all nice and dry, so the fuel on the #3 plug was uniqe, not from running too rich or anything...

so i'm gonna grab a plug wire set and cross my fingers!