Misfire issue? Coil burnt and replaced but still misfiring... NOW FIXED!

[2mAn]

Driving to my buddies and I noticed the car stumbling. When I apply more throttle it was obvious that its a misfire of some sort. I pulled over and saw some smoke coming out from under the hood. I pop the hood and poked under and there was a clear smell of burnt plastic. Figured it was a misfire and found this...



Fast forward and the #2.coil is replaced but I'm still getting the same misfire.

We pulled the other coils and none puked out the plastic like this one did and the car definitely stumbles worse when we pull the wiring. I still think theres a hairline crack on another one thats not obvious like this one was, but Im still hoping you guys have an idea of what I am missing

Any thoughts?

[golde30]

maybe the wiring harness for that coil pack that burnt is damaged? did you check for codes? even OBD1 will tell you which coil pack isnt functioning.

[2mAn]

Unfortunately my car is an 84 and therefore no check engine light yet. Also the new coil still isn't firing, going to check the spark plug but don't have the socket with me now.

[328ijunkie]

OBD2 or 1? might have fried the coil driver....

[2mAn]

OBD1 . how can I check if the coil driver is dead? it seems that the coil itself isn't getting the spark. How do I check that?

Also, should I disconnect the injector if I'm forced to drive around like this temporarily?

[golde30]

Yes you should unplug injector, so you don't have gas washing your cylinder walls. You could read for codes with a peak tool plugged into the diagnostic plug in engine bay...

[2mAn]

Ok, cool I'll see if I can get my java on that diagnostic tool today. I did unplug the injector last night. I hope to get this sorted out asap but this is also my daily which means I have a 5cyl 20v until this is done lol

[2mAn]

OBD2 or 1? might have fried the coil driver....

:bow:

[efficient]

damn that sucks. looks pricey

[328ijunkie]

Throw another ecu in and call it a day :P

[2mAn]

damn that sucks. looks pricey

not too bad when you shop around. found one for extremely cheap

Throw another ecu in and call it a day :P

should have one tomorrow!

the only question I have now is to figure out what caused this.

my theory: I have a E34 harness so its a little short to mount my 318is ECU mount as it is right now, and so I have the ECU just sitting in the glovebox, whereas before I just had it ziptied up against the dash.

loose mounting + sort of stiff suspension + crappy LA roads = fried ECU?

yes?

[328ijunkie]

Ive seen a few things... Ive seen the coil driver fail and take out a coil as youve seen and then ive seen a coil fail and take out the coil driver...
The OBD1 and OBD2 ECUs are not designed to 'need' a ground for the case but i have see a few that have internal shorts that bascially wont work/work properly unless the case is grounded...

[2mAn]

Throw another ecu in and call it a day :P

so this whole thing cost me a grand total of $80 + fuel. New 413 ECU fixed it. Obviously both parts needed to be replaced so no money was wasted throwing parts at the problem

[MrGreen]

Glad your back up and running!