E46 M3 cluster swap

[nando]

To mark the original needle position

[AndrewBird]

What's with the blue tape?

[nando]

Well i have 2 more adapter boards :p

[FredK]

I wish I had a 9K tach. I have no idea what's going on beyond 7. Haha.

[nando]

fuel gauge is still stuck. pissing me off.. but making some other progress:

[nando]

Niice! I'm not sure I would want the gauge to match my e30 gauge though. I'd probably prefer it to be accurate. :p

LOL, well, its a bench setup gauge. Actually, it seems to be very accurate. The gauge face on the e30 just doesnt make sense.

[Vedubin01]

Super impressive Chris, Nice work!

[Wh33lhop]

Niice! I'm not sure I would want the gauge to match my e30 gauge though. I'd probably prefer it to be accurate. :p

[nando]

I cracked the "code" :D

after an hour of changing each byte in the fuel gauge one at a time, I found the pattern.

turns out, they aren't all paired as FF,FF. The fuel curve (in liters) is just FF. the ADC curve (x100) is FF,FF. All this time I thought they were all paired as FF,FF; no wonder I couldn't figure it out. :(

the first 5 FF's are the fuel curve in liters for ADC2. 00, 08, 11, 19, and 21 in hex translate to 0, 8, 17, 25, & 33 liters. the next sequence is the ADC curve for ADC2, 5 pairs of FF,FF 's. ADC1 follows the same pattern starting with 00, 07, 0d, 14, & 18 which equals 0 7, 13, 20 & 24 liters.

with that figured out adjusting the curve is easy! I came up with two that work perfectly.

This one works linearly but most of the resolution is on the "full" end. 0F is 15 liters or 1/2, which is the second value in each curve:
00,0F,17,1C,1E,00,48,00,99,00,EA,01,3C,01,86,00,0F ,17,1C,1E,00,48,00,99,00,EA,01,3C,01,86

I wanted more control over both ends of the curve, so I shifted the 1/2 mark (0F = 15liters) to the center of each group of 5 bytes:
00,08,0F,17,1E,00,48,00,70,00,99,00,EA,01,86,00,08 ,0F,17,1E,00,48,00,70,00,99,00,EA,01,86

08 is the 1/4 mark. each ADC will read 8 liters at 1/4, 8+8 = 16 or about 1/4 of 60l. 00,70 is the corresponding ADC value for the 1/4 mark (11200).

The E, 1/4, 1/2, 3/4 and F marks on the E46 gauge match up with the E30's gauge *perfectly*. :D

I still have one issue to resolve - running the E46 cluster for long periods of time with nothing hooked to the gas gauge input results in the gauge becomming non-responsive. tthe fuel level changes internally as does the ADC, but the gauge's fuel level doesn't react accordingly, unless you reset the cluster or shut it off and turn it back on. I've had it do this a couple times before and was able to get it back, but right now I don't really remember how I did that. it was some combination of shutting it on/off, software resets, and disconnecting the gauge input until the needle responded..

fun times. :)

[nando]

Pigtail harnesses for the cluster, external temp sensor, maybe the LCM.

I would grab ews modules, keys and transponders if you can, the dme is worth more with an ews module.

[RobertK]

I know this kind of work doesn't come cheap but for a clean install I would be willing to pay up.

I may be able to grab some S62 clusters this weekend when I pick up my engines, anything else I should try to grab with them?

[nando]

I have two kids under 3. one "helps" when the other is napping. lol

[Wh33lhop]

LOL if I had a wife I don't know if I'd be able to accomplish or pursue the things I'm doing now. I don't have enough time to devote to someone else right now.

Isn't there a little one in the picture too? Nando you must be a horrible father lol :p (seriously though awesome work, no idea how you do it with all your other responsibilities)

[dude8383]

LOL if I had a wife I don't know if I'd be able to accomplish or pursue the things I'm doing now. I don't have enough time to devote to someone else right now.

[nando]

A parts car is definitely the way to go! I don't think my wife would go for that, though. :p

I just made 30 different calibration files with differing variables for the fuel gauge to try and pick out what affects what. ugh.