M30B35 Auto to 325is Manual

[carlb]

Hey Guys,

I'm confused and need some guidance. I'm putting an M30B35 into my GF's car. It was from an auto 91 535i. I also got a g260 from a 535 to mate to it. In the instructions I've been reading, I had planned to use the wiring from the 325is. Jared's write-up says that because my engine's from an auto the 325is ecu as well.

My problem is that I'm having a performance head built by Bimmerheads and I'm installing a Miller MAF and WAR chip.

Can I use the 325is harness and the 535i ecu? (will it plug)?
If I can't, then I should use the M30 auto harness and ecu and delete the auto related wires?

Anything I'm missing to make this work?

-Carl

[glnr13]

yes, 325is harness works with the 535i ecu but you can't use the m30 throttle position sensor.

m30 TPS is variable (better for tuning)
if you switch to the m30 harness you keep the variable TPS.
if you keep the m20 harness you need to swap to a open/closed TPS and you'll have to cut up the "box" that connects to the injectors which is no big deal and pretty easy to do with a dremel or even a pair of dikes since no one can see the cutting.

[G-Man the Visionary]

yes, 325is harness works with the 535i ecu but you can't use the m30 throttle position sensor.

m30 TPS is variable (better for tuning)
if you switch to the m30 harness you keep the variable TPS.
if you keep the m20 harness you need to swap to a open/closed TPS and you'll have to cut up the "box" that connects to the injectors which is no big deal and pretty easy to do with a dremel or even a pair of dikes since no one can see the cutting.

+1

Also, temp sensors on thermostat might need switched.

[glnr13]

You're right, I forgot about the temp sensor. I'm still trying to figure out which one to use...

[G-Man the Visionary]

You're right, I forgot about the temp sensor. I'm still trying to figure out which one to use...

I think it was the blue one. M30 sensor has 2 connections, M20 sensor has 1. That had me stumped for a while, lol. Twas a lucky guess to fix the problem.

[glnr13]

Hmm. I have the blue still in the thermo housing but didn't try it with my 6cyl cluster. I know it didn't work with the 4cyl gauge. I'll try that for sure tomorrow.

Sorry to hijack, Carlb!

[G-Man the Visionary]

Hmm. I have the blue still in the thermo housing but didn't try it with my 6cyl cluster. I know it didn't work with the 4cyl gauge. I'll try that for sure tomorrow.

Sorry to hijack, Carlb!

ohhhh... good luck with that! And I'm sure he won't mind, it's all an attempt at being helpful, right?

[carlb]

Thanks guys! Very helpful.