Check engine light came on July1, but engine still ran fine. I got codes 5 and 6; Pin 8=none; Pin 14=3. I then replaced the leaky head gasket, (also spark plugs, belt tensioner, water pump; coil boots are two years old). I also cleaned the plugged egr at the intake manifold and wiped off the throttle butterfly using carb cleaner. For access to the egr I unbolted the 3 bolts holding the throttle thingy (looks like my old erector set). Car started immediately, but with a rough idle, oscillating between 600-800 rpm. ASR light came on at first, but later was not on. Drove a few miles; engine died with a/c on; check engine light came on. Retrieved Codes 5,6; Pin 8=13; Pin 14=3; Replaced O2 sensor and started car and idled until warm; Retrieved Codes 6; Pin 8=8and13; Pin 14=3. Drove 5 miles, then idle alternately oscillated 600-800 or 1100-1400. Drives fine above 30; cruise works; drove another 25 miles. Retrieved Codes 5,6; Pin 8=8and13; Pin 14=3. Help.

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

Has your engine wiring harness been replaced? I have the same vehicle with about the same mileage (94 E320, 180K miles) I chased lots of intermittant problems, fault codes, ,CEL, idle surges........After replacing the wiring harness I was able to diagnose/correct the few remaining faults. If your wiring harness is original, I can almost guarantee it is causing you problems. When you completed the work you described, you probably disrupted the wiring harness enough to crumble what was left of the insulation allowing shorts through out the system.

Hope this helps.

I got a new wiring harness last year.

It turns out, I had knocked the vacuum hose off the manifold/throttle body while putting the head/intake manifold back on. After reconnecting that hose I pulled the same codes and tried to clear them. I couldn't clear 5 and 6, but cleared Pin 8=8and13; and Pin 14=3. I then drove the car 30 miles. Now I can't get the primary code light (button 2?) to light at all (this happened once before); and I got pin 14=code 3 again.

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

Code 3 in pin 14 refers to the throttle actuator. I would check the adjustment of the linkages and possibly try to readapt the throttle. I always do it with a scanner but you should be able to do it by turning to key on with the engine off. Let it sit for a minute then turn the key off for at least ten seconds.

If you pull the cross-over off before you do it (and look down to the throt plate) you will see the throttle open after a time and then fully close. If it doesn't do this you probably have a bad harness on the throttle assy, almost as predictable as the regular engine harness.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Steve,

Yesterday I first drove 30 miles back home and this morning pulled codes before I started the car. I got the light when I pushed pin 2 but after the 2 second hold I got no blink at all. I also got pin8=code1 and pin3=code3. Next, I removed the crossover (your test); when I turned the key to run I could hear a whine for 30 seconds, then a click followed by silence. The throttle plate didn't open or even move at all. I tried it 3 times--same each time. I put crossover back and started the car. It revved 1500 rpm for a few seconds, then 1100rpm for about 10 seconds, then settled to a slightly irregular idle at 900 slowing to 800. I drove the car 5 miles and the idle at the first stoplight was oscillating at 600-700. Car runs quite well otherwise.
A few miles later I pulled codes and got pin2 light but no code at all, pin8=code13 and pin3=code3.

According to my dealer receipt, the replaced engine cable (harness) was pn 124 440 56 32. (MB bought the part, but the dealer charged me 5.0 hours labor; job code appears to be 197 CM or 197 WM93). I called the dealer today, and the parts guy said he couldn't tell from the part number if the throttle cable was also replaced.

Could you describe the throttle harness? Does it start at a plug connected to a shiny black wire on the throttle body and then run to the driver's fender and through a dust wall and continue toward the fusebox or firewall? I guess I could slice into it and look for crumbling insulation.

Thanks!

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

From my wiring harness p/n Phil at Mercedesshop parts thinks the throttle harness was part of my new engine harness. So, how do I diagnose the very expensive throttle actuator vs something else? I don't mind pulling codes on a daily basis. Update: car seemed to have much better acceleration today, and with moderately high throttle, rpms went quite high (5800) before upshifting; car hasn't felt that way for months. But, while stopped in D, idle was jumping, almost jerking, from 600 to 800; in N, idle is almost smooth 700.
Thanks!

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