Hello folks, i just rebuilt the engine in my 2007 R56 base, upon initial start up the engine runs, (rough idle), but wondering what sensor/s would effect the tach, and Speedo. Was able to drive it around the house and verified that the speedo is not working, and it seems to have limited power. I assumed that the inoperable tach is causing some of the other issues. Please advise... I have not bought a scan tool yet, and would like advise on which one is good but not too costly...

Thanks all for the help!

 

Perhaps the crankshaft sensor? Though I was under the impression your car won’t start with a bad crankshaft sensor. I believe it also doubles as the engine rpm tachometer. You could have a bad sensor, reluctor wheel, or faulty wiring or connectors/pins could be impeding a proper signal to the computer.

autozone should be able to scan your codes for you, though perhaps it’s also one of the tools they rent out if you can’t make it out to their store with your car. It’s worth checking.