Tach not working on M90 swapped e30??

[spiDmang]

Hey guys,

So this past weekend I purchased a 84' 325e with a euro M90b35 swap. The car runs pretty solid and am enjoying the huge power upgrade!

But like my title states, my tachometer does not work? Neither does my mpg gauge? Can anyone point me in the right direction? I am unfamiliar with the M90.

Any help would be greatly appreciated!!

[Grand525]

Different coding plug on the cluster.

[spiDmang]

Can you elaborate on that more for me please? Which coding plug would I have to source?

[yert315]

you may have a different gauge cluster all together (without the coding plug). Is there a wire harness adapter?

Have you checked all your fuses?

[spiDmang]

I haven't torn into the cluster just yet. I just bought the car, so I'm still familiarizing myself
With the beast

[spiDmang]

Any one else have any ideas?

[wildstoats]

I'm not sure what the wiring is like on the M90 but on my B34 the tach signal is part of the C103 harness not the C101 so it would be easy for someone to overlook. This isn't a great picture but this is what my C103 looks like. The tach signal should be a solid green wire.



The coding plug fixes an issue where the tachometer is working but not accurate. I actually managed to change the coding plug on my car without removing the cluster. Just takes some finesse.

Hope that helps.

[Mark 42]

...My tachometer does not work? Neither does my mpg gauge?

What kind of mileage would an E30 get with am M90B35?
It's lighter than the 635C Si, but obviously for the horsepower it's going to suffer in economy. It sounds interesting... I'm looking for a BMW 3 series or a "New Class" BMW in my area. Trying to balance economy and fun/performance, so I'm just gathering info and looking at ads.

[Kershaw]

if it gets 18mpg i'd be surprised.

[Mark 42]

if it gets 18mpg i'd be surprised.

Bummer.
It sounds like a fun car, but mileage is one reason I had to rule out
a Mk 3 Toyota Supra. My accountant wants decent MPG for my next car

[spiDmang]

if it gets 18mpg i'd be surprised.

This.

That car got 15mpg on average. Maybe less lol

[Mark 42]

Did you sell it? (just curious)