M30 EML HELP! Car won't run...

[tgriffith009]

Was told I should post here as well to get the post some more exposure -

Hey all I'm desperate for some help!

Car - 1991 (11/90) 535i/5

Issue - uncontrollable throttle, eml light is on, random surging, sometimes it will idle, other times it will surge and then die like it's got a vacuum leak. Throttle has a mind of its own and will rev till redline at times if I don't shut off the car.

Solving the problem - I have performed a rebuild per shogun's diy online and it gets a little better each time I do it and then after a couple minutes the light comes back on and the issues resurface.

What I have yet to look into - I have read around that the afm might cause this issue, have not looked at the eml control unit, have not looked at the pedal pointometer as of right now. Replacement parts are extremely hard to come by...

Really appreciate the help! Bought this car about a month again and havnt been able to drive it more than around the block. Can't wait to get her up and healthy.

[shogun]

Throttle potentiometer very seldom is faulty, but easy to test, here are the data:
accel pedal potentiometer testing
E32 Bentley Repair Manual shows the data for testing on page 130-45.

EML Pedal Position Sensor Test
pedal at idle position
manual transmission 0.34-0.43 VDC
automatic transmission 0.35-0.45 VDC

pedal at full throttle
manual transmission 3.1-3.3 VDC
automatic transmission 3.7-3.8 VDC

EML connector pedal position test pin
M70 DME 1.2 brown/violet pin 1
M70 DME 1.7 blue/brown pin 20
M30 DME 1.3 blue/brown pin 20

terminal numbers are molded in the EML connector face. These numbers are very small and may be difficult to read.

set a gap of 3mm / 0.118 in. between accelerator pedal bracket and the idle stop.
To check adjustment, peel back rubber boot from EML harness connector (round big plug left side engine bay close to the diagnosis port) and connect digital voltmeter between specified pin in connector and ground.


Also check the ground cable from engine to chassis.

And the EVAP valve and the EVAP line = tank breather line. if from there unmetered air comes into the throttling valve, that can also cause changes in idle. There are 2 breather valves in front of the engine attached to the air intake box on the M70, see here where we found such a problem, scroll down http://e32b12.blogspot.jp/search/label/Idle
not sure where that breather valve is located in the M30 engine bay.
And of course all the vacuum hoses have to be checked, as you can see from this diagram, they are also connected for example to the fuel pressure regulator http://www.nmia.com/~dgnrg/hose_map.jpg
if the vacuum lines are brittle and leaking, that can cause a lot of trouble.

Any possibility to read out codes?

Then report back.