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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 7 Series / 8 Series > 7 Series - E38 (1995 - 2001)

7 Series - E38 (1995 - 2001)

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  #1  
Old 11-04-2013, 02:57 PM
edognight edognight is offline
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Location: St. Paul, MN
 
Join Date: Jul 2012
Posts: 132
Mein Auto: 1997 e38. schwartzx2
Help with Trans failsafe mode.

Trans Failsafe Issue...weird one, too.

Car had been idling very rough. Changed spark plugs, ignition switch, battery, intake filter, etc. Same. I asked about it previously, and am working on completing all the suggestions. (and yes, I will admit that after a CSB job, I did hook up the Car to itself, and the front O2 sensor to the rear O2 sensor, launching every code in the universe. Re hooked, replaced two O2 sensors, and much better.)

So I cleaned out my Idle Air valve and I did bump the throttle valve in the throttle body, (round thing, twists with gas petal being pushed down.) it twisted, and is about 15degrees off. I noticed this after the fact, at the time I thought nothing of it. I assumed it would just go right back to the position where it should be.

Drive car to work, thinking this would help (cleaning Idle air valve). Car ran worse, and worse, then Trans failsafe mode, the ran worse, and worse, and yuck. Just yuck.

I checked the codes, replaced front two O2 sensors, and about ten codes went down to one or two, (no codes for o2 sensors at all) but also Transmission failsafe mode. Car will start and idle with a very slight shudder, much better than it was before the O2 sensors.

I am pretty sure before the Trans failsafe went on, I had to push the petal about 1/4 way down to move at all, in first gear. BEFORE the trans failsafe kicked in. It was running that bad.

Codes: DME: 117 throttle potentiometer signal

Trans: 9A (154) CAN throttle valve signal. Anomalous signal detected.
64 (100) speed monitoring, trans/engine speed incorrect for gear indicated

49(073) Can WDKBL signal error (throttle valve potentiometer)
4A(074) MD-IND

Drained the pan and got about five quarts of vaguely red non stinking liquid. Filter, gaskets on the way this week.

The last two codes floored me. The first three took about three hours of research.

What I want to hear, is I just have to bump the throttle valve back, and all will be well, but I know better. Can bumping that valve cause total e38 chaos?

Why the trans failsafe mode? The trans runs and shifts absolutely perfectly, before this little debacle.
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  #2  
Old 11-06-2013, 01:23 PM
edognight edognight is offline
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Location: St. Paul, MN
 
Join Date: Jul 2012
Posts: 132
Mein Auto: 1997 e38. schwartzx2
A little bump. I took the potentiometer apart, and everything looked good. I might get a used one, or a new one. The valve had ridden up on the cam lever, tough to explain, but i put it all back, and I thought I fixed, it, but of course it didn't matter. Has anyone had any problems with their potentiometer before? Seems like a strange part to break.
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  #3  
Old 11-08-2013, 05:36 AM
edognight edognight is offline
Officially Welcomed to the 'Fest
Location: St. Paul, MN
 
Join Date: Jul 2012
Posts: 132
Mein Auto: 1997 e38. schwartzx2
Update

I had time to take everything apart and look at things.

Question: what are the two position sensors on the intake called? On my car, they are the same part number and perform similar functions.

There is a potentiometer (twist measurer) (position switch) on the intake top front and easily accessible. Two small #2 screwdriver bolts, not activated by the throttle, and one that is activated by the throttle, harder to get to (needed a 90degree screwdriver to get at it.)

I swapped them and the code for bad potentiometer moved, so I know which one is bad.

Car is charging because I ran it dead with the diagnosis. Still getting the trans failsafe message, but I did the tranny pan, gasket and filter. Tranny pan was perfectly clean, and slight dead metal on the magnet, and VERY slight.

Is it possible to get a trans failsafe message while having no codes on the computer?

Appreciate any help, as I know this is all a lot, and a difficult problem.
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