Rewiring an E30

[n0m4d]

This is my first post here and I apologize for starting off asking for info. I'm new to the E30 (87 325i) and have been prepping it all winter for some spring autocross (with much help from this forum, thanks!). I recently stripped out the interior and now the car is not starting. I assume I have made a noob mistake here but I am trying to work through it (seems fuel system related). I have a few questions that I hope someone could answer for me.

1. From searching I think my issue may be with the 13 button OBC which I have removed. What is the code bypass all about? Is there a post here on how to bypass it?
2. Will the car run without a gauge cluster?
3. One of my "helpers" cut all wiring out from the truck area. Was there a fuel system relay/fuse box in there? I tripped over a post a while ago and thought there was one but its gone from my car now. I can't find that info now.

Again, sorry to post questions but I have done a ton of searching which left me with more questions at this point. Any answers would be greatly appreciated. Hopefully I'll have some contributions soon.

[MattM]

get an ETM, and basically follow all your wiring and find breaks, you shouldnt just go cutting wires out...

does the fuel pump prime when you turn the key?
do you have spark?
are you getting any DME codes?

way to many variable here...

and yes it will run without a cluster or OBC.

[jlevie]

+1

You are going to have to spend some time with the ETM to figure out what was cut out in error and put it back in place.

[DaveSmed]

get an ETM, and basically follow all your wiring and find breaks, you shouldnt just go cutting wires out...

does the fuel pump prime when you turn the key?
do you have spark?
are you getting any DME codes?

way to many variable here...

and yes it will run without a cluster or OBC.

The fuel pump does not prime on these cars. Only turns on when there is an RPM signal from the CPS.


1987 cars are a little different than most, first thing is to make sure no one cut anything on the engine harness. This includes the 3-4 pigtails that come off of the DME harness in the glove box. Pay particular attention to a three pin white connector with (IIRC) a white, green, and black (maybe? I forget) wire. With the key on, the green wire should get +12v.

[n0m4d]

Thanks for the direction! I just downloaded an ETM and will spend some time with it. The diagrams in the bentley manual weren't really helping me. I'm not getting a fuel pump buzz or any fuel smell after a crank at the starter so I'm pretty sure it's fuel related.

This car was once salvaged and had a totally different e30 front end welded onto to it. The whole thing is sketchy which is adding to the degree of difficulty.

One more question. On one of the spark plug wires there was a sensor of some sort, basically a ring around the wire. I assume that was a pickup for the tach and isnt essential for the car to run, but the bently manual makes it seem like its a pulse sensor. Any input on this?

[DaveSmed]

It is a pulse sensor, the DME uses it like a cam sensor. It is not vital to engine operation, but is nice to have.


Odds are good its that stupid plug. C103 or C104 in the ETM. Check it with a volt meter, and verify its plugged in. If it is not getting power, look up in the dash towards the passenger side center vent. There is another three pin connector hiding up there that will plug right into that one that you can try. ;)

[n0m4d]

Very very little was cut and it was only cut in the truck area (the fuel door, power antenna, lights, etc.) Just to me on the same page, the DME is the Mototronic box?

The fuel pump does not prime on these cars. Only turns on when there is an RPM signal from the CPS.


1987 cars are a little different than most, first thing is to make sure no one cut anything on the engine harness. This includes the 3-4 pigtails that come off of the DME harness in the glove box. Pay particular attention to a three pin white connector with (IIRC) a white, green, and black (maybe? I forget) wire. With the key on, the green wire should get +12v.

[jeffw]

without your gauge cluster in your battery wont charge. when the battery light on the cluster isn't working it doesn't charge. my buddy had that issue on his car. and if you pull the obc it will be fine. how much gutting did you do? ecu and icm still there?

[DaveSmed]

Very very little was cut and it was only cut in the truck area (the fuel door, power antenna, lights, etc.) Just to me on the same page, the DME is the Mototronic box?

Yessir. :)

Nothing in the trunk has any bearing on the cars running EXCEPT a ground for the fuel pump, that I think is located under the back seat.

(PS sorry for all of the "IIRC" "I think" etc. been a little while since I tore into the harness)

[dashboardmonkey]

without your gauge cluster in your battery wont charge. when the battery light on the cluster isn't working it doesn't charge. my buddy had that issue on his car. and if you pull the obc it will be fine. how much gutting did you do? ecu and icm still there?

NO! they fixed that in 86

[PeaveyBassist]

NO! they fixed that in 86

Yessir. Verify 12v at the fuel pump with key on and a good ground. If the engine cranks, put a screwdriver on the injectors and put your ear up to the other end. You should hear them clicking (opening). Then verify spark. Pull a plug wire off, plug in an extra plug and set it on the valve cover. Verify you have spark while cranking. Check for those 3 and get back to us!

[DaveSmed]

NO! they fixed that in 86

Well sorta. You still need the cluster plugged in. ;) The bulb can be bad though.

Yessir. Verify 12v at the fuel pump with key on and a good ground. If the engine cranks, put a screwdriver on the injectors and put your ear up to the other end. You should hear them clicking (opening). Then verify spark. Pull a plug wire off, plug in an extra plug and set it on the valve cover. Verify you have spark while cranking. Check for those 3 and get back to us!

Excellent advice EXCEPT for the "Verify 12v at the fuel pump with key on and a good ground." Check this with engine cranking. M20s do not prime.

[n0m4d]

Thanks for the advice everyone. I will look at it tonight and let you all know how it goes.

[n0m4d]

1987 cars are a little different than most, first thing is to make sure no one cut anything on the engine harness. This includes the 3-4 pigtails that come off of the DME harness in the glove box. Pay particular attention to a three pin white connector with (IIRC) a white, green, and black (maybe? I forget) wire. With the key on, the green wire should get +12v.

I spent sometime looking over the problem last night and this is clearly one of the troubled areas. I do not have anything connected any of those connectors that come out of the DME harness. There are 4 connectors, a BL/GY, a RD/BL, a BR/RD and a 3 wire BK/BL, GR, WH (or WH/YW?).

The OBC harness was cut about 2' back and I think the 3 wire connector came from there so I need to sit down with the ETM and figure out where to reconnect them to. There doesn't seem to be corresponding colors downstream of the OBC harness. The green is switched power but I don't know what the other 2 are.

I think the BL/GY is the ebrake sensor and the RD/BL is the Park/Neutral so I'm not as concerned about those. I don't know what the BR/RD connector goes to.

Another concern is the lack of switched power in the harness. I assume most of the green wires in the harness should show 12v when the ignition is on but they don't. I'm concerned that the instrument cluster (which does get power w/ ignition) was necessary to trip a relay somewhere.

Anyway, since you guys were so helpful I thought I'd update you :).

[NC325iC]

Excellent advice EXCEPT for the "Verify 12v at the fuel pump with key on and a good ground." Check this with engine cranking. M20s do not prime.

dont know what m20 youve been working on but my 89 primes everytime the key goes to ON