: misfire detected



boge
02-02-13, 06:59 PM
I recently had my check engine light come on in my escalade. i went to the auto parts store and had it scanned, it read mis-fire no 5 cylinder and radom mis-fire. i just changed my plugs and wires about 5k mles ago, ac delco plugs 41 110 gaped at .40 and napa auto parts wires. i had ac wires but they were gg when i needed hh . i purchased them on line and had limited time to service my ride so i just went to where i went and purchased those wires. my question is what is the best way to trouble shoot the problem ? as far as if its a plug, wire or coil pack.my other question is does any one know which cylinder is number 5 ? As far as symptoms im having with my truck is mostly an occasional rough idle and it seems my truck is burning more gas than usual that started a couple of weeks before the light but along with the rough idle . any feedback would be great thanks in advance.

the cadillac man
02-02-13, 07:41 PM
I recently had my check engine light come on in my escalade. i went to the auto parts store and had it scanned, it read mis-fire no 5 cylinder and radom mis-fire. i just changed my plugs and wires about 5k mles ago, ac delco plugs 41 110 gaped at .40 and napa auto parts wires. i had ac wires but they were gg when i needed hh . i purchased them on line and had limited time to service my ride so i just went to where i went and purchased those wires. my question is what is the best way to trouble shoot the problem ? as far as if its a plug, wire or coil pack.my other question is does any one know which cylinder is number 5 ? As far as symptoms im having with my truck is mostly an occasional rough idle and it seems my truck is burning more gas than usual that started a couple of weeks before the light but along with the rough idle . any feedback would be great thanks in advance.

It could be bad/defective plugs bad/defective wires or bad coil packs
Also the number 5 plug is on the left of the engine

6lbsofSound
02-02-13, 09:48 PM
It's not going to be a plug or wire. It's the coil pack for a misfire condition. If you want to double check the wires take #5 wire off and measure the resistance or ohms with an ohm/voltage meter. Double check it against a random wire to make sure they match. That will rule the wire out. Misfires codes 99.9% relate to the coil.

the cadillac man
02-02-13, 10:00 PM
It's not going to be a plug or wire. It's the coil pack for a misfire condition. If you want to double check the wires take #5 wire off and measure the resistance or ohms with an ohm/voltage meter. Double check it against a random wire to make sure they match. That will rule the wire out. Misfires codes 99.9% relate to the coil.

Don't bad wires or plugs cause the coil to get damaged??

6lbsofSound
02-03-13, 11:51 AM
No plugs or wires don't cause bad coils. The coils are plastic and with age and driving conditions, heat from the engine bay the plastic deteriorates. Or depending on the brand the epoxy coatings crack once that happens the current tends to jump from the coil to the head or any brackets and not transfer to the ignition wire, which cause the misfire. And old school way to check wires or coil is mist water on them and start the car and look for the spark show.

the cadillac man
02-03-13, 12:46 PM
No plugs or wires don't cause bad coils. The coils are plastic and with age and driving conditions, heat from the engine bay the plastic deteriorates. Or depending on the brand the epoxy coatings crack once that happens the current tends to jump from the coil to the head or any brackets and not transfer to the ignition wire, which cause the misfire. And old school way to check wires or coil is mist water on them and start the car and look for the spark show.

Ahh ok I remember that now as I was told to do that for my other car(79 Chrysler cordoba)

boge
02-03-13, 01:59 PM
Thanks for the feedback. I will go test the resistance of the wires on the left side of the engine. Ive been searching trying to find exactly with cylinder is no. 5. And is it o.k if it is a coil pack to just replace the one bad pack or do them all?

the cadillac man
02-03-13, 03:01 PM
Thanks for the feedback. I will go test the resistance of the wires on the left side of the engine. Ive been searching trying to find exactly with cylinder is no. 5. And is it o.k if it is a coil pack to just replace the one bad pack or do them all?

Try like 6lbsofsounds said with misting water on the coil packs on the left side and watch for the spark show

And it won't hurt to just replace the bad coil pack

6lbsofSound
02-03-13, 05:58 PM
If its only one coil just replace the one, replacing all 8 will get expensive.

the cadillac man
02-03-13, 06:12 PM
If its only one coil just replace the one, replacing all 8 will get expensive.

I agree they are pricey even if you get aftermarket

flyingdutchman
02-04-13, 02:34 PM
Just had this issue on my 04 ESV. It was running rough at idle for a few days.Thinking I had picked up some bad gas I drove it for a few days, refilled the tank at a different station and it finally set a P0300 code ( a random or multiple misfire ) Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why. Took it to the dealer who found through the Tech-2 that the coil pack on the number 5 cyl was bad. After replacing the coil, it was idlling smoother but still had a uneven idle and miss at speed. It was found that the remaining coils had corrision on the base of them which were cleaned and new dielectirc grease applied. This corrected the problem

boge
05-11-13, 05:03 PM
Just wanted give an update on my misfire problem. So after checking plugs coil packs replacing wires and air filter I reluctantly went in to the dealer. After rechecking everything I did and more they came to the conclusion it was a bad valve causing the misfire. So I had both heads remachined. And a few smaller things while they were at it.the exhaust valve in the #5 cylinder was not seating properly due to carbon build up.my truck is out feels good to see the manifold bolts replaced.prior to going in I was avging 8.9 mpg now I'm at 15.3

Rob03ext
05-16-13, 06:02 AM
Would youind saying how much all of this costed you?
I got misfire on cylinder 8 right now. Trying to figure out what to do.

boge
05-16-13, 07:40 PM
Two weeks and $2200 at a GM dealership

OneLuv1979
05-21-13, 03:14 PM
What is your mileage on it?