Swilley93

This problem occurred 3 times after i performed a tune-up on my 2000 C230k which i had bought a week ago, it's always cylinder 2. I tried 3 different spark plugs in it, i tried swapping the coils to isolate the issue and no luck. The problem occurs only when i try to push the car past 3200rpm on the highway and the misfire goes away when i turn the engine off and then on again and the returns every time i take it on the highway. Could it be the ECU? Could it be the fuel injector, pump, or fuel pump relay? Mass airflow sensor? or something more serious like a leaky camshaft position sensor or valves? I don't believe it to be the valves though since the compression was good, in fact it was the highest out of all cylinders, the compression in that cylinder was 180psi and the others were 170-175psi. This is turning into a real headache.

Critter

The spark plugs you took out of cyl 2 were they white or a yellowish color. If you put new plug in and it looks same out then look at the injector for that cyl.
Are you just switching around the plugs, do u get the same code??
Coils do tend to break down at higher RPMs, so again what is the code coming back to you
What is the mileage, after all it is a 2000 model year, original coil packs??

Swilley93

They appeared to be normal color. My car has 136,000 miles on it too. I swapped coils 2 to 4 and vice versa, 2 misfired again but like i said the problem temporarily goes away when i restart the engine. I got P0302 this time, the first time i got that and P0130 but i only got 2 codes the first time i checked before resetting. My dad thinks it's the ECU causing the misfire. Before i did the tune-up it ran fine, none of this was happening.

Critter

If the injector is acting up then the ECU shuts down the spark plug firing circuit
Possible vacuum leak or EGR is acting up.
Does the car stall at idle or when coming off highway speed??

Swilley93

So it's the fuel injector? thanks i may give replacing that a shot, i am just not looking forward to spending $100 on a new injector, does it matter if i pull one from a junked C230?

Critter

No issue with a used injector, but recheck your vacuum lines first.
Does the car idle rough when there is no code showing???

Swilley93

Nothing severe, just a very light vibration. I don't think i lined up the air filter box quite right after checking the air filter. But no i did not check the lines.

Critter

Recheck your work first, recheck all vacuum lines end to end,connectors, cracked hoses, after all it is a 15 year old car. Do you hear any whistle noises?? Spray some WD-40 around the rubber lines to see if there are any idle changes, water will also work if you are desperate.
Good Luck

Swilley93

Thanks. Let me add that we contacted the old owner and he said the car was kept up; maintained. My dad thinks everything looks like it's in great shape, especially the engine. But looks can be deceiving.

Critter

Did u use the same sparkplug make and number??? Gap is okay?? I always check even when new. What type plug NGK? or ??
Is this a coil on plug arrangement or does it have spark plug wires?? cap/ rotor

Swilley93

I used spark plugs sold by the dealership, the $8 a piece ones with the MB logo on it and i would presume the use Bosch spark plugs and before those i tried E3.64 spark plugs. It appears to be a coil on plug setup. Those orange plug things are in clys 1 and 3 and the coils are in 2 and 4, all wired together.

Critter

2 coils or 4 coils?,

Swilley93

2 coils.

Critter

you switched coils and got the same code , is this correct

Swilley93

Yes, correct.

Critter

So to backup, this code pops up when u are on the highway, then you reset it, does it come on during normal stop and go driving, say after the car is warmed up?? With no high rpm's??

Swilley93

Well before it happened for the first time i was able to drive it through the city and back home no problem, today i was able to drive it around town no problem. I manged 2-3 hours of driving before the first, 30 mins before that second, and about an hour before the third. So yes, it only happens on the highway when the engine is under more stress. Each time it happened, it happened when i tried to drive on the highway. Like i said, it happens when i try to push the car into higher rpms when overtaking. Car runs fine during normal stop and go driving.

Critter

Sorry my friend but I am back to the coil packs, are they original??
If it was mine I would try to heat up the coils with a heat gun or propane torch (GENTLY) to see if I could cause a code sooner. Coils usually go bad when they are HOT

Swilley93

So why didn't the coil that was in cylinder 2 that i switched with the one in cylinder 4 cause cylinder 4 to misfire? The ecu shutting down the spark plug because of the fuel injector makes sense. In my experience, a dead coil affects 2 cylinders and not just one.

Critter

When a coil gets old it can suffer failure, heat them up and see>

Swilley93

Don't bad coils usually affect two cylinders? Also that doesn't quite explain why the misfire goes away when i restart the engine. Do the coils get hotter than the engine or something? I still have a lot to learn here. Each coil is connected to an orange plug thing. Like i said before, the #2 coil that was put in Cyl #4 did not cause it to misfire while the #4 coil placed in #2 cyl did misfire and cyl 4 has been fine all along. I swapped the coils today, before cyl #2 misfired for a third time.

Swilley93

Update, today i had a smoky start when leaving work but the smoke went away after a few seconds.

Swilley93

Update 2: Swapped the #1 and 2 fuel injectors and took it for a drive today, drove it 40 miles and nothing happened. Accelerated up to 5000rpm and no problems, maybe it only happens when the car was held at an rpm above 3000rpm but i was not able to achieve that today due to traffic. The puff of smoke from starting the car does not occur when the car is started warm. We cleaned out the injectors with a paper towel as well.

ptkacik

I love it when somebody responds after the problem is fixed. So often, we never hear back after the problem goes away.


So.. A bad injector can cause a hot car misfire and will reset when restarting. Maybe the high enrichment of starting breaks the injector coil loose and lets it move again.


I'm guessing the problem hasn't been eliminated unless the injector was replaced but only the owner can finish the story.