1991 850i automatic, EML light with no codes from Peake reader

[shogun]

yes, good advice, I also would check first that the carbon brushes are really pressed in back in place and have contact. I hope it is as easy as that. Same happened here after cleaning, brushes https://www.bimmerforums.com/forum/s...hlight=encoder
Good that you are working on future pro repair solutions for the Bosch DKs. Encoder surface was probably the last hurdle. I remember when I started asking here in 2018 for replacement material https://www.bimmerforums.com/forum/s...hlight=encoder

[dragon850]

yes, good advice, I also would check first that the carbon brushes are really pressed in back in place and have contact. I hope it is as easy as that. Same happened here after cleaning, brushes https://www.bimmerforums.com/forum/s...hlight=encoder
Good that you are working on future pro repair solutions for the Bosch DKs. Encoder surface was probably the last hurdle. I remember when I started asking here in 2018 for replacement material https://www.bimmerforums.com/forum/s...hlight=encoder

The encoder surface is certainly a problem, it wears gradually and the owner never notices the decline in performance over the years until the throttle is dead and EML light is on.
The bigger problem is the resistors inside of the plastic body (behind the encoder wheel), they are at the end of the service life....and are not replaceable. The first generation of the encoder plates (1988) have a higher rate of fail, but 1991 is catching up...

[Exira]

so the problem started after you removed the DK's and reconditioned them? Then I would test them once more, here is a detailed file with all test data for the DK's https://www.bimmerforums.com/forum/s...ng-calibration
do the throttle valves move when you switch ignition on? As soon as the ignition is switched on, the throttle valves move to the position they learned during the last synchronization.
also check fuel pumps, do they work?

Thank you for your reply. The problem started with the intermittent EML light and the car went into a limp mode. So, I removed the DK’s and reconditioned per the write up and the youtube “850i EML LightFix - https://www.youtube.com/watch?v=CvXNT-lWtr4”. I do notice the valves move just a little when the ignition is in on position. I’m new to E31, what do you mean by checking the fuel pumps? What should I look for? I tried to synch per your instruction, but I can’t get the idle to go beyond 2,000 RPM.

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The encoder surface is certainly a problem, it wears gradually and the owner never notices the decline in performance over the years until the throttle is dead and EML light is on.
The bigger problem is the resistors inside of the plastic body (behind the encoder wheel), they are at the end of the service life....and are not replaceable. The first generation of the encoder plates (1988) have a higher rate of fail, but 1991 is catching up...

My 1992 850i E31 has only 65,000 miles and the encoder surface still look decent. I did make sure the carbon brushes are pressed back in place and have contact. I saw that video and make sure I did not make that mistake.

[dragon850]

Thank you for your reply. The problem started with the intermittent EML light and the car went into a limp mode. So, I removed the DK’s and reconditioned per the write up and the youtube “850i EML LightFix - https://www.youtube.com/watch?v=CvXNT-lWtr4”. I do notice the valves move just a little when the ignition is in on position. I’m new to E31, what do you mean by checking the fuel pumps? What should I look for? I tried to synch per your instruction, but I can’t get the idle to go beyond 2,000 RPM.

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My 1992 850i E31 has only 65,000 miles and the encoder surface still look decent. I did make sure the carbon brushes are pressed back in place and have contact. I saw that video and make sure I did not make that mistake.

Like I said, the miles or the encoder surface do not matter, the molded in resistors degrade with age and eventually show way too high of the resistance or infinite resistance rendering your throttle a paper weight.
Why this happens faster on some cars vs others, IDK.
Just FYI I have rebuilt over 400 pairs of these throttles over the years....

[shogun]

what do you mean by checking the fuel pumps? What should I look for?

is there any fuel pressure in the fuel lines? On my E32 750 I test the fuel pumps the easy way first. Engine off, use a cable extension from B+ post and briefly tough fuse 23 and then 24, that are on E32 750 the fuses for the fuel pumps. Then I can hear the fuel pumps running and the fuel lines get under pressure. Check the ETM which fuses are on your E31 in charge for fuel.
You need a Bentley Repair Manual for the E31 and/ or a E31 workshop manual https://e31repair.com/ to solve you problems.
Any chance you can read fault codes?
intermittent EML light and the car went into a limp mode does not automatically mean the DK's are bad. There are many other parts to check like the crankshaft position sensors, cylinder identification sensors etc., just to name a few:
M30/M70 ignition system data accdg to Bentley: Coil primary, coil code # 02051118335 (round type, aka rod-type) terminals 1 (-) and 15 (+) resistance 0.50 ohm, Coil primary, coil code # 20510171101 (ring type ignition coil) terminals 1 (-) and 15 (+) resistance 0.37 ohm, Coil secondary, coil code # 2051118335 terminals 15 (+) and 4 (ctr.) resistance 6.0 kohm, Coil secondary, coil code # 20510171101 terminals 15 (+) and 4 (ctr.) resistance 9.0 kohm
spark plug ends 5.0+/- 10% kohm, shielded plugs 1.0 +/- 20% kohm, spark plug wires 0 ohm (approx.), rotor 1.1 +/- 10% kohm

M70 firing order: 1-7-5-11-3-9-6-12-2-8-4-10, crankshaft position/rpm sensor: 540+/- 10% ohm
from workshop manual: distributor rotor 1+/-20% kohm, angled/shielded connectors 1+/- 20% kohm, spark plug connectors 5+/- 20% kohm, cylinder identification sender coil resistance at 20 degree C (68F) <1 ohm, pulse sender/crankshaft position sensor coil resistance 540 +/- 10% ohm, Donut/ cylinder identification M70, S70: Resistance at 3-pin connector. Measure plug between pin 1 + 2, ≤1 ohm, insulation resistance between pin 2 + 3: ≥ 10 MOhm,

coolant sensors: if the coolant and temperature sensors are not connected or bad, then the system will go to pre-set fail save values, which means it always uses data for a cold engine.
sensors from fender to middle of the engine:
# 8 12621710535 2-POL M14x1,5 , black 5000 Ohm, for temperature gauge sender, spec by Hella: M14x1,5, NTC-Sensor; resistance Ohm: 5000, 544 ; color: schwarz, V: 12.
# 7 temperature sensor water 12621288158 M14X1,5 engine coolant temperature sensor for DME, (20 deg. C, 2500 Ohm.) (White Top)
# 5 temperature sensor water, 13621707366 3-POL-2500-OHM , EML coolant temperature sensor

[8FiftyCI]

You need a Bentley Repair Manual for the E31 and/ or a E31 workshop manual https://e31repair.com/ to solve you problems.

Is there something to this link? Goes to page but nothing works. No option to download, no option to take you to another page. Maybe I'm missing something?

[shogun]

the link works, when you are at the site click in the middle repair manual, new window opens, then click on top "Main Groups", new window opens and you have all 72 sub sections, each sub section has plenty of pages.
Try again, E31 workshop manual https://e31repair.com/