93 300e M104 Start/Idle Problem Details

[croftynsteph]

So...its been about 3 weeks since I put in the new plugs and some system cleanser and I decided I'd take them out to see if I could get help diagnosing the problem.

All 6 plugs are black and sooty on the spark ends. This time, there was no oil on them. Would someone have fixed a valve leak etc and just put the same older plugs back in?

The ignition wires that are tucked in behind the head and connect to the coils and the other 3 plugs were heavily taped and the insulation is splitting on a few of the wires. Under the black plate that covers the injection electronics I found very poor wiring conditions with insulation missing on almost every wire for at least a few inches here and there.

With the plugs in this condition...I was guessing there's a fuel problem...injector related...I could be wrong. I'm begining to wonder if its the wiring issues that are causing my problems. The car starts and runs fantastically when cold (sitting over night or allowed to cool in the shade for a few hours). It has great off the line acceleration and a normal idle.

Once the vehicle reaches operating temp (80 and above) or has been sitting in the sun for sometime...it becomes very difficult to start and requires some throttle to keep it going at first. The idle then immediately drops to just over 500 and it surges no matter what position the shifter is in. It's not a terrible surge (only 100 or so RPM) but when it surges a harsh vibration is sent through the car. Once beyond 1500 the car runs pretty well, with good responsiveness. I believe all of this could also be causing my transmission flare on 2-3 3-4 shifts. They tend to become harder the heavier I am on the throttle.

Would a new main harness replace these worn sections, or do I need to purchase a couple of individual harnesses for the ignition and injection systems?

Sorry for the length and possible redundancy, some new info was brought to my attention and I believe it may not be the O2 sensor and such. All help is appreciated. Thanks

PS: Sorry if the pics are bad-they're from my phone since the Mrs has the camera right now.