Fault code after swap HELP! ASAP...
 

Hey guys after I swapped the diff out I got a fault code, I never got to read it but now I have to smog the car and it gave me a code of 090500 or 90500 (speed sensor). I have replaced the sensor with a new one and it still comes up (CEL), the guy reset it yesterday and it came back on 5 miles down the road... I need to pass this smog tomorrow, what can I do to solve this problem other than swapping back the old diff???...

Do you have an E30 speed sensor or a ti sensor? I believe you need the E30 sensor if you use an E30 diff.

it's an e30 diff but the plug on the sensor is different, so I had to use the Ti's... I even bought a z3 sensor and nothing... the thing is that it does read speed and the difference from nav gps speed to speedo is 1-2 mph, so it is actually reading correctly!...

Luis;

I did the same swap, and used the Ti sensor, as the wiring was not correct to use the e30 sensor. I did not get any CEL, but being OBD1, I suspect it isn't an issue...

Sorry, I don't have any other answers for ya...

Hmm, I was just going off of what Jesse said in the Diff compatibility thread.

My diff came off a 87 325is, it's a 2.93 ratio. The speed sensor from the donor was similar sized, but the connections were totally different.

When i did my swap i put in the E30 or E24 speed sensor in it. I forgot which car the diff came out of, its a 3.25 LSD medium case. I spliced the speed sensor into the wiring and had no issues. Didn't try using the ti's speed sensor since i always read you had to use what the diff came out of.

Check the physical lengths of the two sensors. They should be the same.

It may 'work' (make the speedo show a speed) but the DME is not satisfied.

In the M Roadster diff, the M roadster sensor works flawlessly, and has the same connection on it.

If you can get one of those (and it happens to fit the E30 cover) you should be set. If it doesn't fit (due to length or mounting) you may want to consider changing the rear cover to the M Roadster cover and then use the M Roadster sensor.

Caveat: If the sheet metal ring the sensor 'reads' is different between the stock E30 and the MZ3 you may STILL have problems...

Well...
Swapped the diff, got it smogged, and swapped back again!!!... My arms are hurting like a B...tch!... fun Stuff!

I think I might try the Z3 cover, right now it has the original e30 cover with a z3 sensor... maybe I just have to get the Mroadster cover+sensor... later project though, right now I have an AC compressor to change this weekend, any tips???...

hmm, i think when i did my M coupe diff install i still used the E30/E28 speed sensor.