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Thread: E85 Z4 3.0i Went Into Throttle Fail Safe Merging onto Interstate - Help Diagnose?

  1. #1
    Join Date
    Jan 2006
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    Perry, GA
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    E36 M3, X5 4.6is, E85 Z4

    E85 Z4 3.0i Went Into Throttle Fail Safe Merging onto Interstate - Help Diagnose?

    My wife was driving her 2003 Z4 3.0i automatic (126K miles) today and it had been behaving normally. I wasn't in the car, so all I have to go by is her description of the events. So here goes: She was merging onto I75 when all of a sudden the engine lost power and a bunch of warning lights came on. She was able to get over to the shoulder, but was in a very bad spot on an overpass where the breakdown lane was barely wider than the car with 18 wheelers blasting by at 80+ MPH. Very scary! She called me in a panic and I came to the rescue like a good husband.

    Since the car was in such a dangerous spot, I made no attempt at diagnostics. But I did take a quick look at the instrument cluster. The EML, BRAKE and DSC lights were all on. One was flashing, but it was an intense moment so I can't recall which. Also, the idle was bouncing up and down. I called a tow truck and would try to find the problem after getting it home.

    It took a couple of hours to arrange the tow, get the car home, and grab a bite to eat. Then I went out the garage to start diagnosing the problem. The first thing I did was start it up to see which lights were on and get a better sense of what was going on. The car ran perfectly fine. Only the Check Engine light was on. I drove it around the block and it seemed fine. My wife said that she shut it off and restarted several times while on the side of the road, but it didn't make any difference.

    I hooked up my laptop to pull the codes, and this is what I got:
    28B3 DME: Throttle: continuous adaptation
    2796 DME: Throttle: adaptation values incorrect
    5E19 ABS-DSC: CAN data errorfrom DME/DDE

    The errors all seemed to occurr at 202,870km, which is 126,059 miles. The odometer is reading 126,064 now. So she was able to drive for 5 miles before it dropped into failsafe.

    I did some sleuthing on the interwebs and found several references to the situation, but nothing is an exact match. I found a thread here on bf.c about a nearly identical problem with a Z3 here, which includes a service bulletin from BMW which at first seemed to hit the nail on the head. Here's a copy/paste of the TSB:
    Vehicle Level Technical Service Bulletins All Technical Service Bulletins Engine Controls - MIL/EML Lamps ON/Multiple DTC's Set Engine Controls - MIL/EML Lamps ON/Multiple DTC's Set SI B12 10 02
    Engine Electrical Systems
    July 2007
    Technical Service
    This Service Information bulletin supersedes Advanced S.I. B12 10 02 dated August 2003.
    SUBJECT
    EDK Throttle Faults - Diagnostic Procedure
    MODEL
    E36/7: Z3 roadster 2.5/3.0; coupe 3.0 with M54
    E46: 325i, 330i with M54 up to 06/2003
    E39: 525i, 530i with M54 up to 06/2003
    E53: X5 3.0 with M54 up to 06/2003
    E85: Z4 with M54 up to 06/2003
    E46: 325i with M56 up to 06/2003
    SITUATION
    The "Check Engine" and EML lights are illuminated; engine may go into fail-safe mode. Some of the following intermittent and "currently not present" EDK related fault codes may be stored in DME fault memory:
    On M54 (MS43) equipped vehicles:
    ^(112) 70 hex - Signal throttle sensor, potentiometer 1
    ^(113) 71 hex - Signal throttle sensor, potentiometer 2
    ^(115) 73 hex - Throttle range adaptation check
    ^(118) 76 hex - Plausibility, signal pot 1
    ^(119) 77 hex - Plausibility, signal pot 2
    ^(135) 87 hex - Limp home adaptation, plausibility
    ^(160) A0 hex - Throttle position controller, plausibility pot 1
    ^(161) A1 hex - Throttle position controller, plausibility pot 2
    On M56 (MS45.1), and M54 with MS45.0/MS45.1 equipped vehicles (Z4 and E46 from 03/03):
    ^28B3 - Throttle adaptation, lower mechanical stop not adapted
    ^2796 - EDK adaptation values incorrect

    ^2734 - Signal throttle sensor, potentiometer 1
    ^2735 - Signal throttle sensor, potentiometer 2
    ^27A5 - EDK new adaptation values required
    CAUSE
    The possible causes may include:
    1.Internal failure (defective crimping) of the EDK throttle motor
    2.Resistance fluctuation at X6390 EDK connector due to pin contamination
    3.Signal interruption at X6390 EDK connector due to faulty crimping or defective female pins
    CORRECTION
    On a customer complaint basis only, follow the diagnostic and repair procedure described below.
    PROCEDURE 1.Connect vehicle to DISPlus and read the fault memory
    2.Remove air filter housing and rubber boot between air flow meter and EDK throttle. For removal instruction refer to RA 13 54 250 found in TIS. Do not remove throttle.
    3.Check the EDK throttle production date printed on the black plastic housing of the throttle.If the manufacturing date is "01-05-02" (1st of May, 2002) or higher, the EDK has the latest level of improvements and should not be replaced. If the production date is prior to "01-05-02", the EDK throttle has to be replaced with the improved part
    4.Replace the engine electrical harness regardless of EDK production date.
    The production date on this Z4 is 09/02, so it falls within the date range that could be affected by a faulty EDK (throttle body). The TSB says that if the EDK was produced prior to 01-05-02 (May 1, 2002), it has an internal fault and should be replaced. "Well, that's it", I thought, "I need a new EDK". But when I checked the date on mine, it's 22-07-02 (July 22, 2002), which is after the cutoff date for the defective part.

    This is something else that has me confused: The TSB states that cars with the MS45 version of the DME may show the 28B3 and 2796 fault, which mine is. But according to the TSB, this is only on cars with 03/03 or later production. My car is older than that. But I have the MS45 DME and and seeing the 28B3 and 2796 codes.

    It should go without saying that I need to get this fixed, but do not wish to just throw money at it. How likely is it that the EDK actually is faulty? The other suggested remedy is to replace the wiring harness. I'd consider that to be a last resort. Surely someone else has experienced this problem and found a solution that doesn't involve replacing that (very expensive) wiring harness.

    1998 ///M3/4/5 | 1999 528iT | 2003 Z4 3.0i

  2. #2
    Join Date
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    Houston, TX
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    36 Cylinders
    All M54 Z4's were MS45, only 330i/325i after 03/03 were MS45.
    -Abel

    - E36 328is ~210-220whp: Lots of Mods.
    - 2000 Z3: Many Mods.
    - 2003 VW Jetta TDI Manual 47-50mpg
    - 1999 S52 Estoril M Coupe
    - 2014 328d Wagon, self-tuned, 270hp/430ft-lbs
    - 2019 M2 Competition, self-tuned, 504whp
    - 2016 Mini Cooper S

  3. #3
    Join Date
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    E36 M3, X5 4.6is, E85 Z4
    Ah, I see. The way it's worded in the TSB is a little confusing.

  4. #4
    Join Date
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    E36 M3, X5 4.6is, E85 Z4
    Why does BMW recommend replacing the wiring harness? I checked the 6 pins for the throttle body connector for continuity to the DME connector, and all seem fine. What does replacing the harness accomplish?

    1998 ///M3/4/5 | 1999 528iT | 2003 Z4 3.0i

  5. #5
    Join Date
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    Aberdeen, NC (yes, again)
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    E39M5, E500 4WD
    There are 3 possible culprits: the throttle assembly, the harness, and the DME. I've known of a car, when I was at the dealership, to get the throttle assembly, and have the issue return. Then BMW replaced the harness; didn't fix it. The new DME finally fixed the issue.

    Note, though, that this was one car, out of very many I've known with this issue.

    The throttle motor has two potentiometers, which cross-reference, giving reciprocal values to the DME. If those values don't agree, the DME puts the car in limp mode, to prevent "unintended acceleration".

    Therefore, a dirty terminal, a failing potentiometer, a corroded wire will all cause the same issue.

    You COULD try cleaning both sides of both the throttle plug, and the DME plugs, with Wurth Electrical Contact Cleaner Oil. But, seeing how as the wife drives the car, you might want to go ahead and take the much higher percentage move: Replace the throttle assembly. This is what fixed all the other cars I've known with these codes.

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, owner of German Motors of Aberdeen
    BMWCCA 274412
    German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471

  6. #6
    Join Date
    Jan 2006
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    E36 M3, X5 4.6is, E85 Z4
    Thanks for your insights, Chris! I agree that the EDK is the most likely suspect and FCP Euro has it on sale with 2-day shipping and a lifetime warranty for $160, so I went ahead and ordered one.

    1998 ///M3/4/5 | 1999 528iT | 2003 Z4 3.0i

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