Tach seems off... No idea!!

[bimma360]

Does it make sense to be doin 40mph in 3rd gear and have the tach tell you you are at 4000rpm. ? Its been about two years since i've owned an e30... but that seems just a bit off. And the funny thing is the sound of the motor does not match what the tach is telling me. In other words... the car engine sounds like it is ready to shift when i get very close to redline... everything else seems early. Also, the tach says the car is idling at 1000 and the mpg gauge does not work. Also my previous e30 had a 4.1 lsd and im pretty sure that is not the case with my current car. Any ideas guys... How can the tach be off? Oh almost forgor... this may just be my imagination... but when i rev the car up to redline when its in neutral, the motor sound seems to be on par with what the tach is showing.

BTW when i purchased the car the tach didnt work, and it turned out to be a fuse.

Thanks,
Dave

[jlevie]

40mph in third should be almost 3000rpm (manual transmission & 3.73 differential).

The tach would read high if a PO swapped in a cluster from a 318 and didn't change the coding plug. If not that, I'd suspect the tach itself or perhaps the DME.

[bimma360]

Ok so lets see... how can i go about diagnosing this thing? How can i check if the tach came from a 318? Or how can i test the DME?

Thanks so much for the reply... i was starting to think no one was going to respond.

Dave

[jlevie]

As for the coding plug, you can get the part number from it and check that against http://realoem.com. Other than that, diagnosis will be a matter of swapping in known good parts.

[bimma360]

ok one last silly question.... Which is the coding plug? Im assuming its found on the cluster.