p0302 Cylinder 2 Misfire under load

[blackberg]

So I just got this car and am getting a Cylinder 2 Misfire under load at high RPMSs.
can drive for days with no CEL if driving conservatively. As soon as you step on it hard, it will trigger the CEL. When the CEL first appears, it seems to turn the injector off or something to that cylinder as you can tell it is missing, as soon as the car turns off and back on, the car runs normal.
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I have swapped the coil and plugs from the #2 to other cylinders and the it still #2 triggering the CEL.


This last time it did as I was trying to switch lanes on the freeway from a almost 0mph into a wide open lane, it triggered #2 and #4,

Ive attached the freeze frame pics from scanner, every other time it has been triggered its looked like the one with just #2, and this morning's it was the the both #2 and #4.
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the only common thing on both, and every other time, is the high load (98-99%) and the Manifold Pressure at 38.6 in.hg

any ideas what it may be?

thanks

[Sulaco]

It's called limp mode. It shuts down the fuel/spark in any faulty chambers.

You've already covered the bases, so that leaves the wiring harness as the major culprit. It's a problem on all 94-96 cars (especially C280). A new harness is 760. I've got a spare one from a dead parts car (it had a new harness on it) I would sell for cheaper than new.

[blackberg]

didnt realize that the vehicle specs I filled in the profile dont show on the side...

this is a 2000 C230 Kompressor.

I ordered new spark plugs and the part that goes underneath the coil to start.

is there a particular part of the wiring harness that goes bad?

-bb

[Sulaco]

If it's a 2000, then it's probably not the harness. I also noticed you said you swapped around the coil/plugs.

I'd get new spark plugs and test. If that doesn't do it, get new plug wires.

[blackberg]

Just got the parts in from autohaus yesterday and put them in today, havent taken it out for a drive yet though

I noticed the old plugs had like brown hairlines coming from the top to towards the bottom, almost like spider veins, on 2 and 4, #1 had some too but I had swapped #2 and #1 before.

I also replaced the exetension underneath the coil, but not the wires themeselves. the old extension had no resistance when taking it off the plug, it just came off like if it wasnt holding on to the plug. The new ones where grabbing the plug, was not able to pull them off with quick tug, so I left them.

probably the old extension where not making good contact, lets see if this helps
Ill post pics later, hopefully it will helps someone trouble shoot in the future

-bb