87 325is to 24valve wiring help

[Apex381]

So the new motor is in and I started wiring it in but I've run into a few problems. The 87 was missing a few wires in the c101 that were moved to the either the c103 or c104. I'm having a hard time figuring it out because none of the wiring posted on the forum shows this. And when it is talked about it seems like ppl are calling the c104 the c103 plug.

Any help would be great. I wanna get my car back on the road asap :)

[FredK]

The connections you need to make are all located on C104, a three pin connector.

Pin 1 BK/BU Engine Speed Output
Pin 2 GN OBC Code Relay to E30 main relay terminal 86
Pin 3 WT Present Fuel Rate Output

You need to hook up C104 Pin 1 and Pin 3 to the E36 wiring harness in order to get a tach signal and to get the economy gauge working.

[Apex381]

I did the black wire (pin 1) on the c104 to pin 20 on the e36. My c101 doesn't have anything in the pin 8, 14, or 15. Do you know where those wires would be on the e30 side?

What wire does the pin 3 on the c103 wire into the e36 harness?

thank you for responding fast

[FredK]

C104 pin 3 goes to x20 pin 24

C101 pin 15 is responsible for triggering the unloader relays during start in late models only. Early models used C101 pin 18 to both trigger the unloader relay and the starter.

C101 pin 14 is empty on the 87s. It is the road speed signal, which must be passed to the E36 DME to maximize performance. You can tap this signal from the cluster at C3 pin 26, a BR/RD wire. This would go to x20 pin 14.

[Apex381]

awesome. So from the info I've found pin14 on the e30 side is for the speedometer signal. There is no wire in my c101 for that. Do I need to track down that wire also or is that another dual thing like the pin 15 late model and pin 18 early dual?

[Apex381]

ok so I'm having a starting problem now. I'm not getting fuel. I haven't wired in the two wires on the c104 yet but it doesn't seem like that should be needed for the car to start.

just noticed that I keep blowing fuse 21. That fuse controls fuel delivery. It blows as soon as you put a new one in, even w/ the car off and the keys out of the ign. I unplugged the engine from the fuse box to see if it maybe had something to do w/ my wiring but it still blows the fuse.

[FredK]

The glovebox wiring, is it just dangling in midair? Fuse 21 also powers the glovebox light and rechargeable flashlight circuit. If it's touching anything metal it could be blowing the fuse.

[Apex381]

Thats what I read too, but they aren't touching anything! This is very frustrating. Is 21 suppose to be getting 12 volts with the key out?

[FredK]

Yes, fuse 21 is always hot.

[Apex381]

Ok I solved the problem. There was a loose wire in the engine bay that I overlooked earlier. I taped up the end and now there's no more problems with 21, but there is still no fuel going to the engine. Do you think me not wiring in the C104 has anything to do with this or could it possibly be a bad DME?

[Apex381]

I just tested the DME on a friend's car and it works fine so there is no problem there. I am starting to think that the problem has to do with the engine wiring. I bought a bare engine with no harness so I used the DOHC Wiki to wire the thing up.

this is what I used

oil pressure sensor BRN/GRN or BRN/GRY
front coolant temperature sensor (ECU) BRN/RED BRN
rear coolant temperature sensor (Gauge Sensor) BRN/YEL BRN/VIO
crank position sensor YEL
cam position sensor YEL RED/WHT BRN/ORG
VANOS solenoid RED/WHT GRN/BLU
knock sensor, 1-3 BLK NCA DME PIN 70
knock sensor, 4-6 BLK NCA DME PIN 69
throttle position sensor (TPS) BRN BRN/BLK RED/YEL
intake air temperature (IAT) sensor BRN GRY
idle control valve (ICV) WHT/YEL RED/WHT WHT/GRN
Evaporative emissions valve BRN RED/WHT

anybody see anything wrong?

[FredK]

I wrote that chart on the wiki, and I used it to wire my car up with a 1994 325i E36 manual harness.

Is the engine block ground hooked up? Also, are the power and ground wires that are are part of the diagnostic connector cable hooked up?

[Apex381]

Yes engine is grounded, power and ground wires are hooked up too.

I've read about problems with the CPS maybe I need to test that. Also I only have the one temp sensor in the block for the Instrument cluster, the brown one. People have posted that i two temp sensors in the block because the DME needs one? I thought the DME uses the sensor in the radiator. I do have that one hooked in.

[FredK]

The DME sensor is the blue colored sensor in the head. The dual temperature sensor/switch installed in the radiator is solely for the operation of the electric fan. Whether or not this would cause a no-start, I'm not sure.

[Apex381]

Yeah I dont think it would cause a no start. I need to check out the CPS tomorrow and go through all of those plugs again.