Oh Boy! ....
I had the same problem with my 97 S320. I bought the thing that was on a Chevy Lot, there on consignment with the understanding it had a missfire once in a while. It was in pristine condition....and I bought it in 2001.(w) 71,000 mi. $15,999.00...
I know...Great price Huh?...
Well the test drive was great..but stopped at a light...I felt the miss..stuh...stuh...smoothe...stuh...smoothe..accelerate OK...no more notable miss. Next stop...idle fine....No More Miss...All Gone!
Net day....same ole *bleep*.
Ok...Now in the driveway...here comes Mr. Cockadoodle..Doo, ( ME), with all the tools. Changed the plugs. NG...Same ole!
To make a long story short (and believe u me this story was 2 years old), and I could not find the problem. The car was then taken to the Certified repair shoppe and he put the obd on it and the register was (missfire # 3 cylinder) ...as a test...he swapped the #3 & #5 spark plug.
All was OK..for a few days..then..Bingo!
It missed again at idle at the stoplight!
Brought the car back...Mechanic checks all the connections, and the voltage / resistances yadda yadda yaada...All the same ole routine I did.
Shruug Shoulders...and said," See what it does..I put better plugs in...cleaned the injectors (flush kit)..SOoooo, "all ya owe me is $213.00 plus tax!"...You got it!
Guess who found the problem???..Shamefully to say so....MY WIFE!!!
YES!...I know..hard to believe.
She was on her way to shop at the store, and she calls me on the cell phone..."Hon this car is doing that stutter thing again, only worst!"..I'm like, I don't wanna hear this *Bleep* now! I'm like,"Is the car running and moving ok?"...she's like,"Yeah...but it's awful Jerky!"...I'm like,"WTH".
Then she comes out with the, ( nasty _ itch attitude ), always when it rains or when its foggy out!" Then she goes on, "I think the rain is gettin on the wires or spark plugs inside!" .....I'm like,"Impossible!"
Then it got into a shootin match of words, that I could never ever want to repeat them! I broke down, and wrote all this down, and took the car back to the repair guy in town. A mercedes and foreign car guy. Not just a sts or goodwrench.
The problem was...and after hearing and reading what DW said, he told me..."Jim, I put the car in the dark...started the engine on the obd hookup..all fire sequence etc. OK..I then took a spray bottle with water, and sprayed a fine mist aimed at the front of the engine, and low and behold...obd came up, and the miss started (missfire #3 cylinder).
The coil had a leakage to ground ( High voltage Short to Ground). And it showed no evidence of a crack or trailing of crrent path. (Carbon Tracking)
He replaced the $187.00 Dual coil which in all essence provides high output spark to #3 and #6 cylinder plugs. He said he sprayed a little closer toward the High Voltage Coil...and he could (in the darkness)..see the darn blue arc spark coming out and sparking on the engine head, instead of at the plug.
Problem Solved!...129,000 mi. now...and never a miss or instance of a missfire.
The Mechanic could not believe it. Neither could I!
Took the ole la...er I mean sweet lady out to a nice restaurant for that one!.....I also learned a good lesson! L I S T E N to the W O M E N ! !
........ps: I don't know your ignition configuration, or what the high voltage coil is or looks like...but I'll let you know, This was my intermittent problem! This may help your train of thought.
(((JIMMY^^)))
