becm and ecm help please

I'm new to the forum. I was told this is the best place to get to the bottom of my problem.#I have a '97 4.6 P38 which has had an engine conversion using a#2.8 Mitsubishi#turbo diesel lump. The issue I'm having is the car wont recognize that the engine is running. The BECM appears to be active, as after refitting the battery I can program the key using the door code. I don't appear to have an RPM signal to any of the necessary components i.e tachometer, EAS and gearbox.#Any advice would be greatly appreciated.#

BECM drives tacho, also feeds engine speed readings around telling various systems engine is running via signals received from ECM. On the six cylinder BMW engine, 3 pulses per revolution. Unless you can emulate that you are stuffed.

the mitsubishi 4m40 engine is ok in its own right but fitted in a p38

rick.

I have used the rr gearbox torque converter and cps so the ecm is getting a crank position / rpm signal
As for why this engine 300 Nm of torque and 35+ to mpg

BIGDOBBO said:

I have used the rr gearbox torque converter and cps so the ecm is getting a crank position / rpm signal
As for why this engine 300 Nm of torque and 35+ to mpg

Click to expand...

The ECM maybe, but is it talking to the BECM?

I don't think it is

BIGDOBBO said:

I don't think it is

Click to expand...

That is pretty obvious, how you would interface them i don't have a clue. The Range rover ECMs talks to the BECM as does the gearbox ECU the BECM then coordinates all the systems. Drives the tacho through a data link. If it is not getting the correct signals it can't do that. I cannot think that the Mitsubishi ECM will be compatible with the rest of the system.

You will need a good understanding of electronics and how all the P38 systems hang together to make it work.

Im using the rr ecm

All i need to know is what needs to be connected to the 4.6 loom ie cps maf coils etc etc so the ecm knows the engine is running

I think engine running signal is from the Crank Sensor....

Section 19 Page 20 of RAVE

What's rave

RAVE are the Land Rover Workshop Manuals for their vehicles...

can be had from here

Manuals

I checked the two wires from the CPS at the ECM and there appears to be no signal. Any idea what now??

BIGDOBBO said:

I checked the two wires from the CPS at the ECM and there appears to be no signal. Any idea what now??

Click to expand...

How did you check??

The CPS gives a pulse from a Hall effect sensor....

As the engine turns, the Voltage across the sensor pulses as the Crank 'pegs' go past the sensor which 'upsets' the voltage going through it and the ECU uses this to measure crank speed and engine position information for injection timing....

You can't measure it with a DVM you'll need an Oscilliscope to see the pulses as they happen very rapidly.

In post4 you said you used the RR CPS.If it is not transmitting a signal,then a good idea is to try a replacement?

I was simply looking for voltage but the voltmeter reading was 0.00v on both the black and the pink wire.

fitted a new one yesterday

BIGDOBBO said:

I was simply looking for voltage but the voltmeter reading was 0.00v on both the black and the pink wire.

Click to expand...

Not quite that simple....

The ECU supplies reference voltage to the sensor from the KB (Pink/Black) wire the Crankshaft 'Pegs' effect this voltage as they pass the sensor and the output voltage is is sent back to the ECU through the BY (Black/Yellow) wire...the ECU then 'sees' the difference from what it supplied and what it got back so it 'knows' where in the cycle the crank is...

It then uses this information along with the Camshft sensor to know where abouts in the ingnition cycle the engine is and controls the fuel delivery and spark pulses accordingly...

if the ecu is sending a voltage shouldn't i be able to see that