A lot of variables... Wiring question

[Lord Poseidon]

To start off, I am a long time lurker and dont post much at all. I have had a few e30s and this is the first one I am doing a swap in. I have a 1984 318i as my daily and I am currently putting in a 1999 S52 in it. I actually got the engine out of a 1992 e34 that I bought and it ran perfectly. Whoever swapped it did the full obd1 conversion and I drove it for a couple days with no issues.

So now I pulled the engine out of the e34 and have it fully installed in my 318i and it wont start. I have searched and searched and wired it up to the best of my knowledge and have double checked a lot of things.

So, car wont start. Key on and I get no fuel pump prime. The ecu is not grounding the relay. I ground the relay and fuel pump works. The idle air control valve is buzzing too. I tested the DME in a different e36 and it started right up. There is no EWS wire in pin 66 on my wiring harness either.

Here is how I wired up the square plug to the round connector.

Square plug ----- Round plug

1 --------------- 25
4 --------------- 12
6 --------------- 22
7 --------------- 13
8 --------------- 18
10 --------------- 21
16 --------------- 23
17 -------------- 7


Thanks a million guys. I feel like I am just one wire away from driving this thing.

[Lord Poseidon]

I really have no idea what harness the guy used and that would help for me to troubleshoot. Is there a tag anywhere on the harness that I could figure out a part number? I am pretty sure that its an obd2 harness converted to obd1. There are a lot of plugs hanging but the car ran perfectly before my swap in the donor car setup the exact same way.

Also, do the two wires on the 1984 318s have to be hooked up to start the car or is it just for the tach signal and for speed signal on obc? Thanks guys !

[StereoInstaller1]

AFAIK, the 2 wires in the dash only need to be connected for the instruments to work, car should run.

[Lord Poseidon]

Thanks. I kind of figured that but I am running out of ideas. I am trying to narrow down the x6000 plug so I can check all the wires in the connector tomorrow to narrow down my problem.

[Lord Poseidon]

Just a small update. So, the main relay was bad. It wasnt the normal bad where it doesnt work but the bad where it backfeeds voltage through the negative side. (I have never seen this in all my years of electical work)

To add to the problem. That ground was tied in with the wire that goes to pin 66 (the ews wire although it was black with silver) and fed it voltage causing the car not to start even though it was a non ews harness. The chip must still have ews in it. (it is a 413 red dme)

lol, crazy wiring issues.

[jrdeamicis]

Good catch!