2001 s60 !---Totally Stumped on Engine Misfire

[yabadabadoo1026]

got a 2001 s60. 3 or 4 times in past i have pulled a engine misfire code and it has quickly and easily resolved with a new ignition coil but not this time;

Pulled a P00303 code and replaced the coil and the plug in #3 and then the code became a p00304????????????----put a plug and new foil pn #4 and then the code returned to a P00303 again???????????????????????????

I'm stumped and dont know where to go with it----males no sense. All suggestions/ insight welcome

[vtl]

1. check wire harness to coils
2. if good, do a compression test
3. if good, swap #3 injector with other (or replace all 5)

[abscate]

Don’t put 100% faith in the cylinder assignment on misfire codes. These are generated by sensing the acceleration of the crankshaft sensor at each part of its rotation. Check wiring including grounds, all the coil bolts M6 and the gro7nd bolts need to be tight

[yabadabadoo1026]

1. check wire harness to coils
2. if good, do a compression test
3. if good, swap #3 injector with other (or replace all 5)

i would swap with another cylinder if i questioned if a coil was bad but i put a coil in #3 so dont think that would accomplish anything-----but thanks for the input

[jonesg]

1. check wire harness to coils
2. if good, do a compression test
3. if good, swap #3 injector with other (or replace all 5)

i would swap with another cylinder if i questioned if a coil was bad but i put a coil in #3 so dont think that would accomplish anything-----but thanks for the input

where did you source coils?
I wouldn't trust some sources, like ebay, theres a bunch of copy parts floating around, they even come in fake boxes.

[darylrobert]

Ive had my 2001 for 8 years and changed the coils once, just because. I bought the bosch brand.

[volvolugnut]

Don’t put 100% faith in the cylinder assignment on misfire codes. These are generated by sensing the acceleration of the crankshaft sensor at each part of its rotation. Check wiring including grounds, all the coil bolts M6 and the gro7nd bolts need to be tight

Ground bolts also need to be clean for good contact. Inspect the wiring harness as well. You may have to remove the corrugated wire cover to see wire damage.
volvolugnut

[DavidE7]

The coils don't like old spark plugs because the energy necessary to bridge the gap increases as the spark plugs wear and the gap gets bigger. At minimum check the spark plug gaps. Is your car turbo or non-turbo? The non-turbo factory Beru plugs start to deteriorate a lot at 30,000 miles. They can be regapped to buy some time.

[yabadabadoo1026]

this saga has become even more a mystery----------after initially pulling a P00303 coDE i put a new coil ( EBAY coil i have never before had a problems with after 3 previous ones) and plug in # 3 and didnt correct the issue--STILL PULLING THE CODE . Wondering if may have gotten a bad one i swapped it with cyl 4 and pulled up a P00304 suggesting the coil was bad but before finalizing on that conclusion I buy and install a new coil into #4..Still getting misfire with 2 new coils. Still Wondering if #3 may have been bad i swapped it with cylinder 1 and got a POO300 ie multiple misfires. did some other swaps afterwards and eventually got back to P00303 with a new coil in 3 and in 4. So i swapped 3 where i had to code 4 to cylinder 4 and my code changed to P00304 seemingly confirming i had a bad ebay coil in #3. Went out and bought a Bosch to put in 4 (swapped from 3) confident my code issue would be fixed and NOOOOOOOOOOOOO, still getting a POO304??????????????So now have and new ebay coil in #3( from 4 via a swap) and the new bosch in 4 ----and the other new one out of the car. ABSOLUTELY CLUELESS, and dont want to pay a shop on this old 2001 when a coil and plug should fix a misfire as it always has-----------dont know what else a shop could do. Per above comments just seems illogical a ground or wiring issue with the codes switching cylinders along the way.. ANY MORE THOUGHTS??????????

[vtl]

Next things to check would be compression and valve lash.