1984 325e to 1988 325i Engine Harness Swap

[Frnklwrnr]

I've been reading and watching YouTube videos for the past couple of months and may have gotten a bit over my head thinking this process would be a bit more straight forward.

I have a 1984 325e stock engine and bought a 1988 325i engine wiring harness, crank pulley, crank sensor/bracket, 325i fuel rail/harness/mount (on order) - i realized i needed this after comparing the two harnesses and noticing its not going to be a 1 for 1 swap like i thought. My goal is to turbo the engine so i also bought a Megasquirt2 ECU specific to the 325i harness. I also need to purchase a wideband O2 sensor and an E36 TPS (I think). Condor Speed also has a round to square adaptor that will help with the final connection into the fuse block.

There are multiple triple connectors on the 325i harness and the 325e has double connectors like temp sensors and the like. So I'm not sure how to adapt the triple to the double...

Am I crazy in thinking this will work? I really want to turbo this car to play around with which means I must have a way to tune it. Any help is appreciated. I'm in the SoCal area if that helps with recommendations.

Thanks,
Franklin

[moatilliatta]

It’ll work, and I’m In the middle of doing the same on a 323. Your tach wire is by the ecu, if you can find x20 chassis pigtail you can splice it in. The oil level sensor is about the most confusing part, you have to swap pans or circuits in the harness. 14point7 seems like a good to place for an entry level wideband.


http://www.wedophones.com/BMWManualsLead.htm

[Frnklwrnr]

It’ll work, and I’m In the middle of doing the same on a 323. Your tach wire is by the ecu, if you can find x20 chassis pigtail you can splice it in. The oil level sensor is about the most confusing part, you have to swap pans or circuits in the harness. 14point7 seems like a good to place for an entry level wideband.

http://www.wedophones.com/BMWManualsLead.htm

So you are saying I need to grab an oil pan and oil level sensor from the i car? I would assume the pans are the same but the sensor would be different based on the i harness plug.

[moatilliatta]

Or put your oil level sensor 2 wire plug and wires Into the late I harness up to the x20. Or You could splice it into the I harness on the proper circuit to the x20. Most those harness need re wrapped in tesa 51036 tape.

I’d have to look at diagram, but I think the late extra wire was just a ground.

Also inspect the wires that go around the front of the motor to oil level, alt D+, starter, a lot of those little wires need repair.

[Frnklwrnr]

Or put your oil level sensor 2 wire plug and wires Into the late I harness up to the x20. Or You could splice it into the I harness on the proper circuit to the x20. Most those harness need re wrapped in tesa 51036 tape.

I’d have to look at diagram, but I think the late extra wire was just a ground.

Also inspect the wires that go around the front of the motor to oil level, alt D+, starter, a lot of those little wires need repair.

The i harness actually looks pretty good. If I can splice my e connectors onto the i harness then that is going to be the easiest thing to do. I found a very good i wiring harness diagram so it should be pretty straight forward.

[ForcedFirebird]

If you have the round c101 plug on the chassis, it's a fairly straightforward swap. You'll need the 325i sensors, coolant, crank, AFM, and the DME of course. The oil level sensor connector changed, so that will also need to be addressed.

Just a warning, pin # 20 on the c101 is ground on some cars, power on some and blank on others. If you do not pay attention to it, ti will melt your harness the first time you turn the key.

Pre 1988 cars have the three wires in the glovebox, white connector. Green is driveway lock, black is tach, and yellow is fuel economy gauge.

[TobyB]

84 has square plug, methinks, so c101's some real work.

It's all documented here, ya just gotta dig.

t

[Frnklwrnr]

84 has square plug, methinks, so c101's some real work.

It's all documented here, ya just gotta dig.

t

My 84' does have the square plug and the new harness has the round one. Thankfully Condor Speed Shop makes an adaptor so I just have to plug it in. After reading how the pin out changed over the years I just wanted something simple. Simplicity also comes with a much higher price for the build but I am ok with that when it comes to the main engine harness.

[ForcedFirebird]

There's only a handful of wires that the m20 harness needs from the chassis to operate. Blue alternator exciter wire, black/yellow starter, green coil wire, green/purple fuel pump and brown/black coolant gauge.

Using the late model harness with the round connector, you will still need to do something for the three wires in the glove box. White three pin connector, yellow is the economy gauge, black is tachometer and green is driveway protection (green interrupt for the ignition coil).

[Frnklwrnr]

Thank you so much for that info. A friend and I will start to swap the new harness and accessories on Saturday and will report back. We were wondering ehat we would do with the excess wires in the glove box lol I figured I'd worry about it once everything in the engine bay was taken care of. In a perfect world I would have bought an i car instead if the e, but here we are.

[ForcedFirebird]

Great resource: https://strictlyeta.net/technical/32...stallandwiring

[Frnklwrnr]

My gawd this is the best resource for what I am about to do. Thank you so much.

[Frnklwrnr]

Great resource: https://strictlyeta.net/technical/32...stallandwiring

Can you help with the tps? I thought I read that I could use the e36 tps but it is waaaaay smaller that the e30 tps. I was able to swap the the toothed crank, sensor/mount, and started to run the new 325i harness in my 325e but I was surprised the tps was wrong.

[Reichart12]

Can you help with the tps? I thought I read that I could use the e36 tps but it is waaaaay smaller that the e30 tps. I was able to swap the the toothed crank, sensor/mount, and started to run the new 325i harness in my 325e but I was surprised the tps was wrong.

Hey nice to see you here getting some help. Megasquirt does need the variable TPS that is the e36 version and some wire pins swapped. Someone on here used to sell an mounting bracket that would allow everything to bolt up fine but I cannot remember their name right now. If you're still stock ECU, you don't need to change the TPS.

[Frnklwrnr]

Hey nice to see you here getting some help. Megasquirt does need the variable TPS that is the e36 version and some wire pins swapped. Someone on here used to sell an mounting bracket that would allow everything to bolt up fine but I cannot remember their name right now. If you're still stock ECU, you don't need to change the TPS.

I actually found him and ordered what I needed. I'm adding an MS2 so I def need it. The last thing I need to order is a wideband O2 sensor but the Bosch one that is recommended doesn't have the correct connector for the engine harness. And the stock O2 on my e car is under the passenger seat. I don't think I've found an O2 sensor that has long enough wore to reach. I haven't found anyone asking about this so hopefully someone knows?

Thanks for the help,
Franklin