M10 Tach puzzle :S

[cormier]

Hope I dont sound like an idiot here but I've been searching forums for days and cant figure out whats going on here :S

'84 318 w/ M10 engine -- bought the car with a 7000 tach in the cluster, hits the limiter @ 4200...tried a 5000tach cluster I had lying around, tach reads the same at around 4000.

I was thinking maybe its an old rotor thats reducing the limiter, but the car FEELS like its revving a lot higher than the gauge is letting on

Everywhere I looked says that M10s should rev to 6500--I dont really care about revving high I just want to make sure that my gauge is accurate, which I dont think it is :S.

I was thinking about the "coding chip" for a while, my 5k cluster has one but my 7k cluster doesnt (apparently they didnt come before 86) so wouldn't this make the cluster without the chip accurate (assuming it was from the same car)?

dont know if it has any bearing but the temp guage on each cluster is also screwed, reads all the way hot (checked fuses, grounds)

I guess if anyone could verify for me what tachs came in what models/engines, and what replaces the coding plugs in e30s prior to 86...or really give me any way to make this stupid tach read correctly

Thanks!

[e30jones]

coding plugs are in early clusters. Not sure if you can retrofit an old cluster from a later model to an early 318i. I have an old m10 cluster, I can sell you the tach or the coding plug if you want.

I had this same problem with my first m10. Sometimes it would read lower than other times (hit the limiter at around 5k). I gave the dash a good pound, and it went back to normal. If you search around, there are how-to's on removing the SI board. I'm pretty sure that once I removed mine, I didn't have the problem with the tach anymore.

[BmW1819]

i sent u a pm

[craz azn]

Are you sure its the gauge? I've seen a few early 318s do this problem, but it was actually the distributor that was causing the low rpm limit...

[BmW1819]

yea i seen this problem to

Originally Posted by craz azn

Are you sure its the gauge? I've seen a few early 318s do this problem, but it was actually the distributor that was causing the low rpm limit...

[cormier]

Originally Posted by craz azn

Are you sure its the gauge? I've seen a few early 318s do this problem, but it was actually the distributor that was causing the low rpm limit...

ha if it sounds like THAT at 4k i would NOT want to take it past there , hopefully S52 swap will be in before next summer so Im not too hot on messing with the dizzy on this m10 -- just wanted to know if I was accurate or not, guess it might still be either