E46 Fanatics Forum banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Ride of the Month Challenge!

1 - 20 of 20 Posts

·
Registered
Joined
·
202 Posts
Discussion Starter · #1 ·
Had my car checked for a weird problem. My tach says I'm idling at about 200 rpms most of the time.
Garage checked and of course it's idling where it should around 750 or so. So I'm trying to figure out what might cause a misread of the RPMs?
I particularly don't like that it's reading low since it means I might be pushing redline more often than I mean to.

Any ideas are welcome?

New cluster?
 

·
Registered
Joined
·
608 Posts
Use the OBD "hidden" features to get a digital tachometer reading. Compare it to what your needle is reading. Also, if you haven't already done so, do the cluster test to make sure your cluster is functioning properly. Then...get back with us
 

·
Registered
Joined
·
202 Posts
Discussion Starter · #3 ·
Thanks for the quick reply. I haven't played with the hidden OBD functions yet and don't know how to do a cluster check. I'll do a search and figure it out.
 

·
Registered
Joined
·
202 Posts
Discussion Starter · #4 ·
OK - got the RPMs to show on the OBC. Sure enough, they read in the 7-800 range at idle, while the analog dial shows 1-200.
I could get the OBC test to 2.0 (cluster test), but never figured out if how to make it actually run. Tapping the button gets it to go to 2.0 and 2.1 which pops back to 2.0. Holding it down pops you out of test mode and you have to start all over to get there. Waiting for a minute doesn't help either. Hmmm.
 

·
Registered
Joined
·
202 Posts
Discussion Starter · #7 ·
Ok - did the cluster test. Everything moves smoothly, but the tach only goes up to 6.5 instead of pegging at 7.
It's like the dial is just twisted and set to 500 rpm low.
 

·
Premium Member
Joined
·
3,573 Posts
Did you pull the needles off at some point to change the gauge backplate or the LEDs. Sounds like the needle wasn't but back right. Try this really quick. disconnect the battery for a few seconds. This will reset the instrument cluster needles. (pulling the fuse for the cluster will also work, just make sure the gauges make a small rumbling noise for about a second after the fuse it put back in. If it doesn't do that then wrong fuse.) If that doesn't work then open the cluster and remove the needle turn the shaft counter clock util it stops and then replace the needle aligning the tip to the tiny white dot on the faceplate.
 

·
Registered
E46 F10 W204 W212
Joined
·
5,171 Posts
I think the cluster reset also makes it buzz like scottjoh describes. Try that first since you already know how to access the menus, and before you go resetting needle positions.

On the secret menus, I think the reset is the last option.

Paolo
 

·
Registered
Joined
·
202 Posts
Discussion Starter · #10 ·
I've only owned the car for a few weeks. No cluster mods for me. It also looks relatively stock so I don't think anyone before me did, but I could be wrong.
I guess I'm going to be opening up the cluster no matter how much that scares me. Is removing the needle as simple as a gentle pull?
 

·
Registered
Joined
·
202 Posts
Discussion Starter · #11 ·
OK - I managed to reset the OBC. It did nothing except reset my clock.
I was curious, any have a picture of what their tach looks like when the car is off? My tach needle falls so far past zero that it's practically resting on the needle for the stupid gas mileage gauge. It easily sits down at minus 500 rpms.
So I'm really thinking that somehow the needle is just set at 500 rpms below where it should be.

So, can I just pull the cluster and pull the needle off and rotate it 500 rpms worth and then push it back on?
 

·
Premium Member
Joined
·
3,573 Posts
Yup. Like I suspected. The needle is on wrong. Either the plastic around the shaft cracked and is now barely hanging on or someone took it apart and put it back wrong.

First remove the two rubber button caps off by pulling on them. Remove the screws holding the cluster together. Pull the cluster apart and using a fork (the kind you eat with) as a pry tool and pry the needle off. Rotate the shaft fully counter clockwise and re install the needle aligning the tip of the needle with 0 on the gauge (the little white dot is only on the speedometer). Reassemble and reinstall and your done.

 

·
Registered
Joined
·
202 Posts
Discussion Starter · #13 ·
Thanks, Scott. The fork trick worked. It scared me that I had to put some effort into getting the needle to pop off, but it did so cleanly without breaking something... which would be typical for me.
I'm all set now. Did the OBC test and found that the dial and engine read are perfectly pegged.
My only real question is how would this get messed up in the first place. I hope someone didn't do a glory shift in the car and peg it all the way past 7k rpms and it twisted on its spindle. I guess I would notice some other problems with the car if that were the case, though.
 

·
Registered
Joined
·
2,441 Posts
Thanks, Scott. The fork trick worked. It scared me that I had to put some effort into getting the needle to pop off, but it did so cleanly without breaking something... which would be typical for me.
I'm all set now. Did the OBC test and found that the dial and engine read are perfectly pegged.
My only real question is how would this get messed up in the first place. I hope someone didn't do a glory shift in the car and peg it all the way past 7k rpms and it twisted on its spindle. I guess I would notice some other problems with the car if that were the case, though.

Here's a trick to test out your calibration.

Accelerate to 60 MPH (or 70 MPH) and engage the cruise control.

RESET the AVG. MPH on the OBC.

CHECK to see that the OBC registers 60 MPH +/- 0.4 or so. I just say 0.4, its not some offical calibration, but it should suffice. I know mine will fluctuate just slighlty.
 

·
Registered
Joined
·
8,127 Posts
Here's a trick to test out your calibration.

Accelerate to 60 MPH (or 70 MPH) and engage the cruise control.

RESET the AVG. MPH on the OBC.

CHECK to see that the OBC registers 60 MPH +/- 0.4 or so. I just say 0.4, its not some offical calibration, but it should suffice. I know mine will fluctuate just slighlty.
Doesn't work with newer e46s (I think the change happened in 03 or 04). BMW changed it so that the OBC calculates the speed with the "correction" factor included.
 

·
Registered
Joined
·
2,441 Posts
Doesn't work with newer e46s (I think the change happened in 03 or 04). BMW changed it so that the OBC calculates the speed with the "correction" factor included.
Danke!

Didnt know. :thumbup:
 

·
Premium Member
Joined
·
3,573 Posts
Thanks, Scott. The fork trick worked. It scared me that I had to put some effort into getting the needle to pop off, but it did so cleanly without breaking something... which would be typical for me.
I'm all set now. Did the OBC test and found that the dial and engine read are perfectly pegged.
My only real question is how would this get messed up in the first place. I hope someone didn't do a glory shift in the car and peg it all the way past 7k rpms and it twisted on its spindle. I guess I would notice some other problems with the car if that were the case, though.
>...how would this get messed up in the first place.
You got me. Those needles are really really tight on those shafts. There is no way the torque of that little motor could twist the needle if it hit something. If the needle was on tight and the plastic wasn't cracked someone must have messed with it. I can't think of any other explaination.

:facepalm: OrientBlau, why are you suggesting a way to test calibration of the speedometer? OP's problem is with the tach, not the speedo.
 

·
Registered
Joined
·
202 Posts
Discussion Starter · #19 ·
Someone had definitely been messing around in there at some point, though. There were only 4 of the 6 or 7 T10 torx screws in their holes. Still baffling why or how someone would mess it up?
 

·
Registered
Joined
·
2,441 Posts
:facepalm: OrientBlau, why are you suggesting a way to test calibration of the speedometer? OP's problem is with the tach, not the speedo.

Good point! :eeps:

<~~~~~ :facepalm:
 
1 - 20 of 20 Posts
Top