Coding plug?

[asubimmer]

So those of us coming from a m42 or m10, will we have to change to a diff coding plug? Like the m20 plug? I need a new cluster anyway I guess

[BigD]

No need for a new cluster, just a new coding plug. If you want a proper 7k redline then your only choice in E30 is the M3 cluster but you'd have to keep the plug and chance the rpm pulse from the engine.

[asubimmer]

I was saying I need a new cluster cause the odo went out and the fuel and temp are unreliable. ;)

I would like an m3 cluster but I'm not so sure how well they go in. Some people say that they work fine and others say the rpm's are off etc...

[KangamangusDriver]

I hear they do work, however are slightly off.

I went from a M42 to a M50.
Changed the coding plug, worked just fine.
May have been slightly off for a race car, however fine for me!

[MIKe30]

I hear they do work, however are slightly off.

I went from a M42 to a M50.
Changed the coding plug, worked just fine.
May have been slightly off for a race car, however fine for me!

whats the difference between the m3 cluster and a 325i cluster?

and what do you mean by you think its slightly off - what is off the speedo, the tach, etc?


i'm pretty sure i need to change that coding plug thingy... i'm all geared out at 7k rpms in 5th at 100mph with e36 trans and 3.25lsd. i dont think PO changed it when he had the swap done.

parts of my cluster dont light up (tach and temp) at night, and the odo doesnt work properly... so if i just pick up a working 325i cluster would i be good to go?

TIA

edit: and what is redline on an m50b25tu? is that what the difference in the m3 cluster is about?

sowwy bout all the questions!!! i been searching a lil bit, this thread seemed to fit my questions best....

[PiercedE30]

Mike: yea, just throw a 325i cluster in and you should be good. I think the redline is like 7000 or 6900(non chipped). or I may be wrong and it's around 7200.

[1990m3]

i put a e30 325 coding plug in my 318is and have had good luck. Seems to work just fine like it was from the factory.

[asubimmer]

2 questions...

my speedo doesn't work at all and I still have the m42 cluster and coding plug, any other m42ers have that prob?

and two, the coolant sensor that you need to replace in the head of the e36 for the e30 one. Do I need to use the m20 one since I need the m20 coding plug or can I use the one from my m42?

[MIKe30]

2 questions...

my speedo doesn't work at all and I still have the m42 cluster and coding plug, any other m42ers have that prob?

and two, the coolant sensor that you need to replace in the head of the e36 for the e30 one. Do I need to use the m20 one since I need the m20 coding plug or can I use the one from my m42?

i think i can answer question one. i am pretty certain i still have the stock m42 cluster on my car and my speedo seems to work. when i pass those speed clocker sign thingies in the road it reads like 4 mph faster than the sign says tho, but i think thats normal for our cars


thanks for answering my '?'s

[1990m3]

I have the original m42 cluster in my car. It works fine and reads in line with all my friends cars I have driven along side with.

Your swap shouldn't really effect your speedo as the speedo sensor is in the differential. I don't think there is any wiring in the swap that interferes with the speedo in general?

[asubimmer]

well I put the later speed sensor in the 3.73 lsd. The early plugs are diff than the late ones. Could that be the prob?

[1990m3]

well I put the later speed sensor in the 3.73 lsd. The early plugs are diff than the late ones. Could that be the prob?

I'm using an e28 diff that has a different plug for the speedo cavle as well. I just removed the e28 unit and installed the factory speed sensor from the 318is diff into the e28 diff. now the e30 plug on the body plugs right into the diff with no splicing or crimping. Both my e30's are 90 and 91 so I guess I didn't realize that earlier e30's had a different plug.