Crank no start with M54 swap

[clarinetnerd]

Like the title says. M54b30 from an automatic e39. Chassis is '91 325i. DME is MS43.

• Turning the key to on gets the fuel pump going, I can hear that clear enough.
• Spraying brake clean (the flammable kind) down the intake doesn't help, so it isn't getting spark.
• After cranking for a while (probably 10+ seconds) I can't smell any fuel, so I don't think the injectors are running either.
• No fuel and no spark tells me it's probably EWS.
• Using MS4x Flasher, I wrote MS430069 (with MS4x wiki's immobilizer bypass patch) onto the DME. Crank, no start. Tried it with an unaltered version of the wiki's MS43x custom firmware, which has the immobilizer bypass patch included. Same result.
• MS4x Flasher shows me a half-dozen diagnostic codes:

A little poking around online gave me definitions for most of these:

• DTC 113 is motor throttle valve potentiometer. That makes sense. I swapped the throttle body for an M52 cable throttle. I realize this might also be causing problems.
• DTC 11 is coolant temp sensor at the outlet. Makes sense; that sensor isn't plugged in any more.
• DTC 35 is the secondary air pump. Makes sense, that got deleted.
• DTC 140 and 126 are evap related.
• 125 is for the cooling fan.
• 115 is "range check for throttle position adaptation". Read above (at 113) for the throttle situation.
• And DTC 69 is for the fuel pump relay, which makes little-to-no sense.

Other than the throttle situation, this is a fairly basic swap, following the guide posted on this forum. I did rebuild the VANOS while I was doing everything, but I can't imagine that would have any impact.


Let me know if you need any more information.

I'm really out of ideas and I don't know where to go from here.

[TobyB]

So for MS43, I like PASoft's BMWScanner 1.4 Go to e46fanatics.com, and it's in the pinned 'important links' thread at the top of the general forum.

You need a piece of hardware for it from ePay or similar, but it's usually not too expensive.

Likewise, get a dongle for INPA, and those 2 will get you through just about anything.

The DME really wants the MDK (throttle) components to be present and working-
if it thinks the throttle is open, or can't prove that it's closed, it won't let the engine start.
You could test this by simply hooking up the throttle and pedal, and seeing if it starts.

Thinking about this a little, I'm not sure MS43 is going to work without the MDK-
it uses 'driver's wish' for quite a few calculations, and it gets that from pedal position...

t

[clarinetnerd]

So for MS43, I like PASoft's BMWScanner 1.4 Go to e46fanatics.com, and it's in the pinned 'important links' thread at the top of the general forum.

You need a piece of hardware for it from ePay or similar, but it's usually not too expensive.

Good to know; I downloaded the software and I'll get the hardware on its way. I already have an INPA dongle.

The DME really wants the MDK (throttle) components to be present and working-
if it thinks the throttle is open, or can't prove that it's closed, it won't let the engine start.
You could test this by simply hooking up the throttle and pedal, and seeing if it starts.

Thinking about this a little, I'm not sure MS43 is going to work without the MDK-
it uses 'driver's wish' for quite a few calculations, and it gets that from pedal position...

So I started thinking that might be the problem, and I tried something a little creative and a little stupid. I still have the electronic throttle body, so I just reconnected that. For the pedal, that's just a couple of potentiometers. So I threw in a couple resistors (with a 1 ohm resistor, voltage dropped by 0.135v across the resistor on sensor 1, and half that on sensor 2. According to https://openinverter.org/wiki/BMW_El...Throttle_Pedal it should work as long as the voltage drops by anywhere between 0.3 and 4.2 volts on sensor 1. 6 ohms of resistance gives me pretty much exactly a 0.7 volt drop), and that should make the DME "see" an accelerator pedal that's mostly held open.

Tried to start it, it didn't start. More testing tomorrow, or maybe over the weekend.

[TobyB]

It cross- checks between the 2 pots-

you'll get a pedal error if it doesn't like it, tho, so that should at least help diagnose it.

t

[clarinetnerd]

Yup. I realized eventually that the two sensors didn't necessarily use the same resistor.

To make a long story short- now I have a 200-ohm resistor on sensor 1, which should mean the DME sees 0.76 volts, and a 875-ohm resistor (actually multiple resistors in series, but they added up to 875) on sensor 2, so the DME sees 0.38 volts. Both of those should return a measurement of "idle", and sensor 2 is almost exactly half of sensor 1 (yes I know the numbers I have here are exactly half, but the measurements varied by a millivolt here and there). Tried to start, no start. DME says pedal sensor plausibility- too much difference between the two.

After looking at my circuit diagram again, I think I know where my mistake was.
I wasn't certain whether the computer was comparing the signal voltage to power or to ground, so I had two sets of resistors and put each sensor wire in the middle. I think that's messing things up, but I'm not at all sure.

[clarinetnerd]

I've fully given up on trying to fake the pedal. I just don't know enough about it or how it works. So unless someone wants to take a multimeter to their pedal and give me resistance numbers for every pair of pins, I'll just have to make do with the pedal I ordered.