e30 m50 swap problems

[jogfrogjog]

So I swapped an m50 into my early model 318i that used to have an m10 in it...

go it it running and what not, but I have an issue in that is keeping going into limp home mode... the motor is 94 m50 with vanos. I pulled the code once and thought I took care of things and it went back to limp home mode. Any Ideas? I need to pull the codes again, but don't want to ask the guy that did it for me because the first time he did it free of charge and he works for a shop...

I don't have a check engine light so no code :(

any ideas?

[FredK]

Did you wire up the vehicle speed (x20 pin 14) to the E30 cluster?

[jogfrogjog]

I connected pin 20 from the e36 harness to the RPM wire on the back of gauge according to AKG's chart.... I dont' recall connecting 14 to anything...

http://www.akgmotorsport.com/usm50swap.html

[OrganicMechanic]

Okay, the fuel pump problem is easy. AKG have got the pins wrong on their chart.

They have got E30 pin 6 going to E36 pin 13. You should have E30 pin 13 going to E36 pin 13.

E36 pin 13 is a 12v signal coming from the E36 fuel pump relay. This passes through pin 13, and needs to go to E30 fuse 11, and then off down to the pump.

AKG have got a 12v signal coming from the E36 fuel pump relay and connecting to E30 pin 6. This is a 12v signal from fuse 9 that would normally drive the O2 sensor relay. They basically have 12v connecting to 12v coming the other way.

I also noticed they don't have any connection for the Rev counter. You need to have E30 pin 9 connected to E36 pin 20.

You also need to connect E30 pin 14 to E36 pin 14. This is the road speed signal into the DME. Without this signal, you will not reach maximum RPM.

If you want the Unloader relay circuit to operate correctly, you also need to connect E30 pin 15 to E36 pin 15.

Unfortunately, I can't see any of the above connections stopping it from firing (assuming you give the fuel pump some power).

It's got to be worth connecting as above, and have another go though.

Ian.

wiring chart

check here

[jogfrogjog]

thanks, but I don't have a later model e30, I have the early model with the square connector...

any info on that?

[jogfrogjog]

Did you wire up the vehicle speed (x20 pin 14) to the E30 cluster?

where on the back of the cluster would that connect?

[SamE30e]

I think it's any wire on the green connector near the bottom, don't hold me to it.

[jogfrogjog]

I think it's any wire on the green connector near the bottom, don't hold me to it.

can anyone else confirm this?

[jrdeamicis]

Take an OHM meter (you know... DMM) and tie it to the GRAY wire on the M50 wiring harness coming out of the X20 connector and then put the other lead to ground. Then put the car to on and press the gas pedal five times. The computer will ground out the CEL and start showing you the CEL.

I have the entire pin out for the old style E30 connector, if you need any help with the wiring please email me @

jrdeamicis @ gmail.com

[jogfrogjog]

sent you an email...

thanks for the CEL idea, I'll try that when I get home... I would think an LED would work to if it's connected to that wire and grounded...

I'll take a look and see what it says...

One of the things I'm wondering is if it might be an issue with the power to the fuel pump relay wire needing to be straight power from instead of the fuel pump relay from the e30 side.

[jrdeamicis]

The wiring chart I emailed to you works on my car just fine w/ a VERY similar setup. The computer grounds out to create the CEL, not V+ so you would just be grounding out your LED.

[jogfrogjog]

Thanks for the help, I got the check engine light to work, but can't read it...

so I think I'm gonna give up on trying to read morris code, I don't have my manual with me at the moment and I'm getting fed up with my car...

I might try to take it back down to the one guy and hope he won't charge me for reading the codes...

[jogfrogjog]

looking at AKG's chart, it's looking like there is a wire for tach (engine speed input) (pin 20) on the e36 and there's another wire for vehicle speed output (pin 14), what's the difference?

IIRC, I have pin 20 hooked up to the tach wire on the back of the cluster and the tach works fine with the use of a coding plug from a 6 cylinder e30. Does Pin 14 need to be hooked up then? and if so, what should it be hooked up to?

[jogfrogjog]

I took a video of the DMM hooked up to the Check Engine light wire... can anyone figure out the code? the 1 means off, a number other than 1 mean on.

http://www.youtube.com/watch?v=rklKNa-1cfI

my understanding is that the initial on for 5 sec while stomping, then off then on for ~2.5 second showing that it's gonna start the test then the code from there... generally the pattern I see is short... long... short... long...

[jogfrogjog]

bump