Irritating M52 E30 Swap problem

[Scrambler]

Hi, Having an issue with an M52 swap. Engine cranking but no fuel and probably no spark delivery. Putting it down to engine ECU not having correct signal from auto trans ECU. Found out I had to splice a wire in after I trimmed down my engine loom.

Looking for Brown black wire that comes from auto transmission ECU as I chopped everything out of my engine loom which was related to the automatic transmission ECU which was stupid.

I've got the harness from the Auto trans ECU and it shows a brown/black wire but I'm having trouble looking for it on the engine loom side so I can splice it into any red/white wire as I assume this makes the engine ecu constantly think its in park and safe to start. Is there a diagram someone can put me on to in order to find it? I've undone my engine loom and most of the wires I cut I left length on and wrapped them so I could join back on if something went wrong but I can' find this little brown/black bugger.

Update: Been through my whole wiring harness and I knew that all the wires I cut off from the auto trans control unit I capped off as to be able to easily find them if I needed them again but I'm not seeing this brown/black wire which is related to pin 26 (Automatic transmission range, switch). Any ideas from anyone? I'd be very grateful.

Thanks

[DesertBMW]

M52 swap has nothing to do with Starter operation and nothing to do with ignition switch operation on E30 chassis.
All E36 cars will start and run with automatic transmission computer unplugged.

So what ever you are doing has nothing to do with problem that you are having.

[Scrambler]

M52 swap has nothing to do with Starter operation and nothing to do with ignition switch operation on E30 chassis.
All E36 cars will start and run with automatic transmission computer unplugged.

So what ever you are doing has nothing to do with problem that you are having.

Hmm interesting so this guide in setting up wiring for a 24v E30 swap is leading me astray?

"If you ended up with a harness out of an automatic car simply cut all of the wires out of the engine harness that belong to the automatic transmission computer. Automatic transmission computer is wired directly to the engine computer harness; the only wire that needs to be modified is a “brown/black wire pin 26 transmission ECU”. It needs to be connected to any “red/white" wire on the main relay."

http://www.rmeuropean.com/bmw-e30-m50-swap.aspx

I've found my old transmission ECU harness I removed and it has exactly this wire coming from it. I can see most of the wires I've cut pertaining to the auto trans ECU but that brown/black one is no where to be found. Does it come into the auto trans ECU as brown/black then back out of the auto trans ECU as a different wire going into the engine harness?

I've checked all wiring and I'm using a DME that has EWS delete remapped for M3 exhaust and m50 intake I bought from ebay so I'm running out of things that could be wrong. Other wise its the DME/CPS thats bad or both. I would really like to eliminate this Automatic Transmission Range switch though but if all e36's will start without trans ECU then I'm stumped.

[Chariot]

Have you checked the crank position sensor? It is pretty easy to get to and just Ohm it out. If the CPS is bad the car will not get spark or fuel.

[Scrambler]

Yep checked that, thanks for your additional help. Is there anyone else that can help me out?

[NC325iC]

what year car?

[pazi88]

Have you read the fault codes from dme? From those you can normally see clearly why it refuses to start.

[Scrambler]

The E30 is a 1989 and the m52 donor was from a 1995 E36 328i. I've always found it confusing as all the Bentley manuals say the M52 started production in 1996.

Have you read the fault codes from dme? From those you can normally see clearly why it refuses to start.

Will get onto this. I don't have a scan tool but will be a good idea to grab one now.

Reading the Bentley manual I found out what the pin 26 BRWN/BLK wire is. It comes out of the Trans ECU and goes to a few various things like the starter relay, cruise control and then on to this automatic transmission range switch. It shows that it will complete the circuit if PARK or NEUTRAL gear is selected then it goes into a green/grey wire and onto the fuse box.

Now I'm still a bit stuck. Will probably have to get the scan tools and report back.

[Chariot]

One other thing you could check is power to the DME. Take a look at the pinout for your DME and see what pins should have power when the car is keyed up. It should be 1 or 2 pins.

This wouldn't necessarily find your issue, but if the DME isn't getting power that would be something to look into.

[Peelsbimmer]

Have you check you fuel lines to make sure you have them going to the right places? I know when I was doing my swap and couldn't get any fuel. It was because I had the lines mixed up. Longest 2 days ever!!

[M3PO]

Just an FYI, I chopped out all of the auto trans wiring just like you did and I had no issues.

[Scrambler]

Got some where with this yesterday. Managed to find a pin 49 on the ecu that was supposed to be connect to the ignition so fixed that up and then I got life from the fuel pump.

Turned the key to the On position and it primes the fuel rail but doesn't keep going if the key is turned to ignition/starter position. Thought everyone said these cars don't prime the system?

I was using my old DME that came with the donor car that still has EWS on it so I guess thats why it doesn't fire just cranks over...

My remapped ecu with EWS removed from it doesn't really do anything. It just makes the fuel pump click weirdly and not prime the system so it must be a dud.

Also a side note, my diagnostics won't work on the 20 pin OBD2 port. Keeps just saying initializing like its going to connect then never does anything just says disconnected. Any ideas?

[ob_318is]

So I believe I am having the similar start issues as Scrambler. Hopefully someone can help.

Info:
'87 325ic auto (converting to manual)
'97 s52, with computer (ews delete etc, computer from manual car)
Auto engine harness.
Re-pinned c101

I have not attempted to remove the brown/black wire from pin 26 on the transmission ecu wiring and splice it to the red/white wire on the main relay. I don't think this is necessary to start the car, but I have read the same information you did and will attempt it tomorrow.

Here is a video on my start attempt, I have no spark, but have ground and power at the ignition coil, fuel is also pressurized to the fuel rail, feed and return hoses are correct.

https://youtu.be/TyFMnAleIOU

Any help is appreciated!

[Klug]

Your best friend is the ETM, I also had a '98 S52 auto harness with auto '92 auto vert. I was getting wonky things happen with the FP being constantly on when ignition was on. I took the time and verified/checked/cut out every unnecessary lead from the harness for the sake that I felt more comfortable with the wiring and to verify that everything was done correctly.

Since your also dealing with auto- here is my wiring harness pinout (didn't use an adapter and ran the X20 s52 harness directly into a single C101 connection to the e30.

Thanks for all the input guys, finally figured it out! Blame the harness adapter! Somehow had the C101 Pin #12 CEL light hopping on the switched power Pin #8. Which apparently just freaked out the e30 side into running the fuel pump non stop.

End all be all, I've noticed that you can't trust a single harness diagram out there, since it seems that everyone is totally different on the X20 side. It gets confusing very quick. Best thing is to lay out the whole harness and pin by pin figure out what actually you have going on. Plus it gives you peace of mind of what is actually going on with the DME. Plus your able to delete a whole bunch of AWS, ABS, EGR and EWS wiring that was unnecessary from the harness. I also ended up wiring the C101 directly to the s52 harness- didn't use a harness adapter to cut down on wiring and other issues that can come up. So one connection from the s52 harness to the e30 body over C101... now it looks like the engine was made to fit an e30!




Below is my spreadsheet that I used- maybe it'll help someone out in the future. Thanks for everyone's input!

X20 was from a '98 E36 M3 S52 Auto
C101 was from my '92 E30 Vert Auto

[ob_318is]

Klug thanks for the wiring spreadsheet. I will compare my wires. I don't trust myself enough to dismantle the harness and connect one by one. I do have two extra harness laying around and can give it a shot. I like that you printed the ETM because looking at it on the computer or a screen gets annoying, and my ADHD gets in the way.

But going to revisit this.




Sent from my iPhone using Tapatalk