1992 400E-101,000 odd miles I am getting codes 2,7, and 17. I have changed out spark plug wires(Beru), spark plugs(Bosch Super), ignition cap, rotor, and o2 sensor already. I have a miss during idle cold and hot. I have quadrupled checked over everyting I repaired .I also checed for leaks in vacuum hose connections. I have some black residue around the mass air flow but, if it was leaking. I think a code would pop up showing this is the problem. When, I checked the harnees now, I get more codes. So, I suspect it is the wiring harness. Has anyone does this as a DIY? Do you have to disconnect the battery? I opened up the sleeving and sure enough the insulation is flaking like the pictures that are shown on this website.

Try using the "Search" button to look threw the archives.

Maybe try here to start.

Thanks for the reply but, I did check. None of them mentioned anything about disconnecting or not disconnecting the battery or much detail. The reference is for the intake manifold not, wiring harness. I saw that post also. It seems pretty lengthy and complicated. I just hope I do not have that problem as well.

The reason why I changed all the above items were first they were overdue except, the oz sensor. The code tripped so, I did it. The spark plug wires was the idea from the MB dealer themself but, decided do it myself since it took them 3 days just to diagnose the problem. So, I took it upon myself since, I did not want to wait any longer for the car not, to mention it was cheaper for me to do it myself. However, that did not resolve much except a little higher rpm during idle about, 200rpm more or less. Same intermittent miss during idle.

I cut into the wrapping around the wire harness and low and behold. It looked exactly like the pictures that have been posted. So, even if it is not due to this problem. I am going have to change it out anyways.

A footnote to all this is that lately. My door locks will pop unlock simultaniously by, itself when driving. If it is associated to the idling problem. I haven't a clue. When this happens. I press the driver's side door with my arm to lock it again. The lock from the driver's side door locks but, not the other doors. When I lock it from the outside when the car is off. The locks work fine including, the windows rolling up and the sunroof closing. No problems whatsoever. It is only the occasional unlocking of all the doors by itself. If someone knows anything. Let me know.

I had a bad coil on my 94 e320. I had tried to check it with an ohmmeter but somehow fooled myself--the internal connection was erratic. Independent tech found it--cost me 3 hours labor!

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TomO
94 E320 Wagon, 170k, totalled in 2006
2002 BMW 525i Wagon, 75k
1991 BMW 318is (two of 'em)

s60,

You don't have to disconnect the battery to replace the wiring harness, although I don't think it would be a bad idea to do so. Make a diagram or take some digital picutres of the existing harness before removing. As I recall, the trickiest part was where the harness goes through the "heat shield" toward the rear of the engine compartment. I took my time, had a helper and it took about 1.5 hours to complete. A good portion of this time was spent drawing the diagram of all the various connections.

RM92400E