Speedo and Tach working correctly?

[alexbaby88]

How does one ensure that the rpm and speed readings from the speedo and tach are displaying correct readings, following the swap of an M50 or M30 engine into an E30?

[optima]

because the speed is taken from the diff the only thing that can effect it is the size of your wheels

[alexbaby88]

A friend has an E30 M3 cluster and running an M50. The tach seems to be reading higher than it should. 205/50x16

The readings don't correrspond to the data from the rpm/speed java script computation from the Unixnerd site. http://www.unixnerd.demon.co.uk/revs.html

What else could be wrong?

[ian332isport]

When I did my S50 conversion, I also used the M3 instrument cluster. Even with the 6 cylinder coding plug fitted to the cluster I found the Tacho read approx 12% high.

I used one of these calibration modules to correct this:

Dakota digital SGI-8

Ian.

[alexbaby88]

OK that confirms my suspicions then!

That Dakota module, was it easy to fit?

Thanks Ian, you're a star!

[ian332isport]

That Dakota module, was it easy to fit?

Dead easy

You just need to give it power (12v & GND), and connect the wire that normally goes to the tacho to the input and then run a wire from the output up to the tacho (it effectively connects in the middle of the existing tacho wire).

Ian.

[nadz325i]

When I did my S50 conversion, I also used the M3 instrument cluster. Even with the 6 cylinder coding plug fitted to the cluster I found the Tacho read approx 12% high.

I used one of these calibration modules to correct this:

Dakota digital SGI-8

Ian.

oh that looks ace for my conversion to, genius , i have the e30 m3 cluster (mph ) for my 325i but i did read stories that the speedo/rev need calibrating and saw the dakota module. hmm cant wait till pay day....

OFFTOPIC (sorry) ian would you know if there were any differences in the petrol tanks/guages betweek the s14 and the normal 325i/sport e30? i got the m3 mph guages from the USA.

Thanks.

[ian332isport]

OFFTOPIC (sorry) ian would you know if there were any differences in the petrol tanks/guages betweek the s14 and the normal 325i/sport e30? i got the m3 mph guages from the USA.

Thanks.

I'm pretty sure the E30 M3 has a different sized tank to a regular E30.

When I initially fitted my M3 gauges (also MPH speedo ), I found the fuel gauge was a bit off. I just fitted the original E30 fuel gauge in it's place. If you are careful, you can pop the red needle off and fit it on the standard E30 gauge. Failing that, you could just paint it.

Cheers,

Ian.

[nadz325i]

OFFTOPIC (sorry) ian would you know if there were any differences in the petrol tanks/guages betweek the s14 and the normal 325i/sport e30? i got the m3 mph guages from the USA.

Thanks.

I'm pretty sure the E30 M3 has a different sized tank to a regular E30.

When I initially fitted my M3 gauges (also MPH speedo ), I found the fuel gauge was a bit off. I just fitted the original E30 fuel gauge in it's place. If you are careful, you can pop the red needle off and fit it on the standard E30 gauge. Failing that, you could just paint it.

Cheers,

Ian.

kool, i thought so, did read before that there different sized tanks,

my understanding of the mph/rev guages is that if you pop the needles off you loose the correct 'position' of the needles, so the needle goes out a bit, but abit makes a difference.

does this apply to the petrol guage if i pop the needle of?

also last quesiton on this topic because i want to change my ***mileage on the m3 cluster to my current CORRECT speedo, is this striaght foward, change with a tooth pick/thin object/needle?

thanks for you help.


***note..my mileage change is correction to m3 speedo to match current milleage on existing speedo, sal/ant/mot can confirm this if anybody has suspicions of clocking going here...regards

[ian332isport]

kool, i thought so, did read before that there different sized tanks,

my understanding of the mph/rev guages is that if you pop the needles off you loose the correct 'position' of the needles, so the needle goes out a bit, but abit makes a difference.

does this apply to the petrol guage if i pop the needle of?

also last quesiton on this topic because i want to change my ***mileage on the m3 cluster to my current CORRECT speedo, is this striaght foward, change with a tooth pick/thin object/needle?

thanks for you help.


***note..my mileage change is correction to m3 speedo to match current milleage on existing speedo, sal/ant/mot can confirm this if anybody has suspicions of clocking going here...regards

Your speedo should still read accurately. The signal for this comes direclty from the diff sensor and is the same on the M3 as it is on the rest of the E30 range.

I would not recommend popping the speedo or tacho needles. It's almost impossible to get them back on in the correct position. As mentioned above, the speedo will be fine, and the Dakota box will sort the tacho. I don't think this applies to the fuel gauge, as it does not have a stop pin for the needle to stop against. As long as you make sure the needle is pointing to the same position on the gauge as the one you removed it will be fine. I didn't have any problems with mine.

It is possible to 'adjust' the milage reading. This is also something I did on my car to retain the original reading. I'm sure there's an easy way to force the dials to read what you want, but I used the old fashioned method and used a drill to wind it forwards. I can't remember exactly which of the little gears on the speedo I used, but one of them drives the odometer. I seem to remember having to remove one or more of the other gears to allow me to drive the odometer on it's own.

Cheers,

Ian.

[nadz325i]

excellent piece of advice, much appreciated.


Thank you.,

[alexbaby88]

When I did my S50 conversion, I also used the M3 instrument cluster. Even with the 6 cylinder coding plug fitted to the cluster I found the Tacho read approx 12% high.

I used one of these calibration modules to correct this:

Dakota digital SGI-8

Ian.

Ian
what about your speedo? Did you find out if it was accurate? Mine seems as though it is a fair bit optimistic.

May need both the tach and speedo correcting gizmos from Dakota....

[ian332isport]

When I did my S50 conversion, I also used the M3 instrument cluster. Even with the 6 cylinder coding plug fitted to the cluster I found the Tacho read approx 12% high.

I used one of these calibration modules to correct this:

Dakota digital SGI-8

Ian.

Ian
what about your speedo? Did you find out if it was accurate? Mine seems as though it is a fair bit optimistic.

May need both the tach and speedo correcting gizmos from Dakota....

Alex,

I found my speedo to be fine.

All you need to check when changing speedo's is that the 'K' number printed on the face of the speedo (small writing at the bottom) is the same as the one you are replacing.

I believe this number relates to how many pulses from the diff sensor equals one kilometer travelled (or something along those lines )

Assuming this 'K' number matches, and you are running the correct sized tyres, then it should be okay. If it isn't for some reason, you could use one of the Dakota Digital modules. I believe they do one specifically for correcting speedo's, but the theory's the same.

Cheers,

Ian.

[alexbaby88]

Ian

Thanks for the speedy response.

As I was not the original converter, I do not have the original speedo...

Will try and check with a buddy with an E30. Otherwise more business for Dakota...

Cheers!

[alexbaby88]

Oh one more thing Ian.

Presumably you installed one of the Dakota gizmos? If so where did you locate and place the device?

Thanks

[ian332isport]

Oh one more thing Ian.

Presumably you installed one of the Dakota gizmos? If so where did you locate and place the device?

Thanks

It's secured to the bottom of the ECU with Velcro.

[Brianmoooore]

Speedos are designed to over read, as it's a legal requirement that they NEVER under read. Usual for speedo to read about 85MPH at 80 MPH.
Easily checked with GPS. I find that the limit function on the OBC is spot on though.

[Brianmoooore]

Anyone ever worked out what the pot. on the speedo PCB is for?

[ian332isport]

Anyone ever worked out what the pot. on the speedo PCB is for?

Brian,

I believe it's for calibration.

There was a post ages ago where someone had done a load of testing with signal generators etc and posted quite a good article on it.

I'll see if I can dig it out.

Ian.

[ian332isport]

Anyone ever worked out what the pot. on the speedo PCB is for?

I'll see if I can dig it out.

Ian.

Christ, that was easier than I though it would be

http://www.e30zone.co.uk/modules.php?na ... alibration

[alexbaby88]

Oh one more thing Ian.

Presumably you installed one of the Dakota gizmos? If so where did you locate and place the device?

Thanks

It's secured to the bottom of the ECU with Velcro.

Would that be in the glove compartment?

[ian332isport]

Oh one more thing Ian.

Presumably you installed one of the Dakota gizmos? If so where did you locate and place the device?

Thanks

It's secured to the bottom of the ECU with Velcro.

Would that be in the glove compartment?

Assuming we are talking UK spec RHD cars here, it would be above and to the right of the steering column.

The one above the glovebox is the ABS computer.

Ian.

[Brianmoooore]

Totaly forgotten about that thread - It wasn't that long ago, and I contributed to it as well! That's what age does to you!
So, in these days of GPS, it should be possible to tweak the pot a bit, check it through the range with GPS, and end up with a speedo a lot more accurate.

[ian332isport]

Totaly forgotten about that thread - It wasn't that long ago, and I contributed to it as well! That's what age does to you!

I had also forgotten about it until you mentioned the pot

So, in these days of GPS, it should be possible to tweak the pot a bit, check it through the range with GPS, and end up with a speedo a lot more accurate.

I can't see any reason why that would not work. I wonder if it's possible to drill a small access hole in the side of the casing to allow access without stripping the cluster down each time. You could always plug it up with a blanking grommet afterwards.

Ian.

[alexbaby88]

When I did my S50 conversion, I also used the M3 instrument cluster. Even with the 6 cylinder coding plug fitted to the cluster I found the Tacho read approx 12% high.

I used one of these calibration modules to correct this:

Dakota digital SGI-8

Ian.

Alex,

I found my speedo to be fine.

All you need to check when changing speedo's is that the 'K' number printed on the face of the speedo (small writing at the bottom) is the same as the one you are replacing.

I believe this number relates to how many pulses from the diff sensor equals one kilometer travelled (or something along those lines )

Assuming this 'K' number matches, and you are running the correct sized tyres, then it should be okay. If it isn't for some reason, you could use one of the Dakota Digital modules. I believe they do one specifically for correcting speedo's, but the theory's the same.

Cheers,

Ian.

Hi Ian
I have K=4838 on the bottom of my speedo (calibrated in km/h) which is the same as that on the original one, but it still feels as though it is over reading.

Could it be the coding plugs? How do I tell if I have the right coding plugs?

I believe the donor car for the engine was an E34, not sure of the source of the final drive (S3.15).

Any ideas?