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Green '02 E320 Wagon
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555 Posts
Discussion Starter #21
The coils go up to 10kv sometimes, so you may end up getting some nasty shocks, nevermind destroying your DMM.
Thanks for the recommendation. I thought a multimeter would be more precise than my spark plug tester which uses a light between the coil and the plug.

The check engine light is back (because I erase it each time it turns on). It shows cylinder 5 misfiring, even though I exchanged its coil with cylinder 4, the resistance on its wires were correct, and its plugs looked ok. Cylinder 1 (which now has the bad wire from cylinder 2) didn't report a problem yet.

What else could it be? I might visually inspect the cylinder 5 injector. I added a bottle of Liqui-Moly Jectron injector cleaner to the fuel tank. I will replace all the wires, the fuel filter, and the air filter because they're all quite old. I will check the live data with Torque Pro once my Bluetooth scanner arrives. I'll keep working through the misfire diagnosis checklist and searching the forums for more things to check.

I'm going to research STFT and LTFT. My Freeze Frame data keeps showing STFT B1 much lower than STFT B2 (except for the first time when the car had significant power loss when driving). Readings I've gotten include:
ECT = 185 F
STFT B1 = -0.78%
LTFT B1 = 7.03%
STFT B2 = 1.56%
LTFT B2 = 7.03%
MAP = 14.77 inHG

ECT = 118 F
STFT B1 = 0.78%
LTFT B1 = 7.03%
STFT B2 = 0%
LTFT B2 = 7.03%
MAP = 10.63 inHG

ECT = 167 F
STFT B1 = -4.69%
LTFT B1 = 6.25%
STFT B2 = -3.91%
LTFT B2 = 6.25%
MAP = 13.58 inHG

ECT = 102 F
STFT B1 = 0.00%
LTFT B1 = 6.25%
STFT B2 = 4.69%
LTFT B2 = 6.25%
MAP = 11.52 inHG
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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3,292 Posts
Swap the spark plugs from 5 to 1 and see what happens.
 

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Registered
Green '02 E320 Wagon
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555 Posts
Discussion Starter #23
I'll swap them when I install my new wires. The cylinder 5 plugs look the same as those in 2 and 1.

Is it reasonable to pull the fuel injector for cylinders 4 and 5 to visually compare them? How else could an injector be tested?
 

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