Dyno plot of s50 swap

[aeryk7]

Yeah thats how people get ripped slap a cover on an m50 bam looks like an s50 to the normal eye.

[TWRViper]

The speed sensor (Black/white) wire is tied to the green wire coming from a three-wire connector. When I unplug this wire, the tach stops working. Does that sound right?

[aeryk7]

The speed sensor is plugged into the back of the diff, not sure what your are speaking about

[NickP]

The speed sensor (Black/white) wire is tied to the green wire coming from a three-wire connector. When I unplug this wire, the tach stops working. Does that sound right?

If you follow the green wire does it seem to go to the back of the instrument cluster around the speedo? If so it should be fine.

[NickP]

The speed sensor is plugged into the back of the diff, not sure what your are speaking about

He's talking about the wiring going into the DME / ECU. The black / white wire is the signal input wire on the obd1 harness

[TWRViper]

If you follow the green wire does it seem to go to the back of the instrument cluster around the speedo? If so it should be fine.

Yes it seems to be. When I disconnect it, the tach stops working. Is this the same speed sensor that, when disconnected, acts as a govener and kills power?

[aeryk7]

He's talking about the wiring going into the DME / ECU. The black / white wire is the signal input wire on the obd1 harness

I think i was a little tired when i was thinking about what he said

[NickP]

Yes it seems to be. When I disconnect it, the tach stops working. Is this the same speed sensor that, when disconnected, acts as a govener and kills power?

It shouldn't affect the tach. What are you disconnecting - a single wire or a 3 wire plug (C104).

[Jason89i]

there are three speed signals.

- one road speed signal comes from the diff and goes to the speedometer. dont touch that.
- one ROAD SPEED signal that goes from the speedo, through the c101, to the ecu. its the same signal that goes to the speedometer, but is safer to mess with it at the c101.
- one ENGINE SPEED signal that goes from the ecu, through the c101, to the tachometer.

if the ENGINE SPEED signal is not hooked up, your tachometer will not work.

if the ROAD SPEED signal is not hooked up, vanos will not actuate, ignition/fuel ratio will be changed, your idle will not kick up to 1100 when you are rolling down the street. in essence, your car thinks you are sitting at a stop light reving the engine, trying to show off to the girls sitting at the park bench. it will not impress them, or the g-tech.

cheers, jason

[TWRViper]

ok, i don't know what c101. Sounds like a connector.

1. CHECK, Signal from diff to speedo works because the speedo works
2. Road speed signal that goes from speedo to ecu
3. CHECK, engine speed signal that goes from the ecu to tach works because tach works. That is the black and white wire connected to the green wire from what I remember.

So #2 is in question. Is that pin 42? I don't think my idle is 1100 when rolling.

[TWRViper]

Just talked to TMS. They said that if the speed sensor is not hooked up, the car revs fine until 6000 RPMs. From 6000-7000 RPMs the computer goes into a "limp" mode or soft rev limiter. That might explain what I am seeing on my dyno chart.

Anyone have a link to a good explaination of what to check to make sure the speed sensor is connected correctly?

[Jason89i]

Rip out the e30 m3 cluster and run an IS cluster problem solved. It is an option though

what does the cluster have to do with the ecu not getting the road speed signal???? your opinion is unfounded. its a waste of money. both the "I" and "M" clusters give the same signal to the ecu AND the obc.

Anyone have a link to a good explaination of what to check to make sure the speed sensor is connected correctly?

plug in a good scan tool. (i dont think the peake 5 will pick it up.) the code should be stored in the ecu.

the connection commonly refered to as the c101 connector is the ONLY connector that links the engine to the chassis. its right next to the fuse box. bmw calls it "c101" for the e30 chassis and "x20" for the e36 chassis.

Normally i would recommend breaking out the wiring diagram, but i understand the tough spot your in.....heck, you didnt build the car. of course, the person who built your car SHOULD be doing all this work. They SHOULD have notes, charts and a good understanding of how the systems work. but i feel compelled to help.

for the road speed signal.......

ROAD SPEED signal comes from the cluster to the c101 on the e30 chassis:
- pin 14 blk/wht wire (for 88+ "i" cars)
- pin 14 blu/yel wire (for late m3's)
- does not exist at the c101 for most "e" cars. you will need to tap into it between the obc and cluster, drag wire into engine bay, patch to x20.

ROAD SPEED signal goes to the m50 ecu from the x20 connector:
- pin 14 blk/wht wire (for the 93-95 e36 m50tu.)
- pin 14 brn/red wire (for the 91-92 e34 m50nv.)

cheers, jason

EDIT: I just noticed you have an 86. please call the person who built your car and specifically ask them if the hooked up the road speed signal. most people (including here on this board) want to just copy some cheesy / almost correct pin diagram off the internet. i have not seen anyone address this issue for older cars. so, i bet that there are A LOT of cars running this way.

[Mike B.]

PM me your email address and I can send you the ETM section for an '86 E30 to help with tracing the wiring.

[TWRViper]

WWWWWOOOOOOOOOO!!!! I found the speed sensor wire from pin 42 and traced it to the instrument cluster. The insulation was gone at some spots and wire was exposed. I taped it up and plugged it in the back.

IT NOW REVS TO 7000 INSTEAD OF 6800!!!!!!

I think it pulls a little harder but kinda hard to tell since it was fast before! I am so excited!!!! A guy at work is going to lend me a wideband so I'll be able to check the AFR. I need to redyno now!

[bmw332i]

Good on ya! Let us know how it turns out, and post the two graphs so we can take a look.