M50 Lambdas

[Sooty]

Mainly for Brian or Ian this one but, what are the implications of running an M50 (vanos) without the lambda sensor in place?
I've finally managed to get mine started & ticking over.
It seems OK @ 750ish rpm & it's smooth enough but I can't find any plugs in the E34 engine loom that a Lambda would plug into.
Am I missing something?
Cheers guys

Iain S

[jmc330i]

I know the S50 engine wont run properely without the Lambda sensors fitted (it has 2), so I would of thought the M50 would of been the same.

It will run, but will probably run in limp mode to protect engine and cat (not that you will have a cat fitted) from running either too rich or too lean.

What year E34 did the engine come from? Im just wondering if there was some early ones that didnt have Lambdas fitted???

[Sooty]

It's a later one from a 95' with EWS II.
According to the ETM, there's only the one probe fitted (I did'nt pull the engine unfortunately, so I did'nt get to see for myself).
I've always thought that limp home mode was an idle-ish rpm setting
Mine revs quite freely when I hit the loud pedal.
Iain S

[DanThe]

It will run too rich, I tried mine without the lambda and it was cack. The plug should be mounted behind the passenger side engine mount arm

[jmc330i]

A '95 car will have a Lambda fitted to protect the Cat/engine. So the loom on yours should (hopefully) have the plug somewhere

The limp mode is like a default setting to keep the air/fuel ratio at an acceptable ratio as not to damage engine/cat. The Lambda monitors the oxygen content in the exhaust gases and tells the ECU to lean out or richen the mixture to keep the air/fuel ratio somewhere round 14.7:1. If the Lambda is faulty (or not there) the ECU reads it as a fault and goes to the default setting - runs slightly rich IIRC because that is better than running lean.

[Sooty]

The plug should be mounted behind the passenger side engine mount arm

Thanks for the help guys.
It's much appreciated but I'm a bit puzzled as to why I can't find anything for the lambda to plug into.
I would have thought the plug would have been part of the engine loom?

[jmc330i]

You havent got any cut wires hanging around have you??
Maybe cut right back to where they would run into the loom - I dont know where that would be on the M50 loom.

[Sooty]

I'll get under & have another good look tomorrow.
If the guy who pulled the motor has cut the wires, I'm going to ream his little pink bottom with the larger end of an M20 gearbox

[Sooty]

UPDATE:
Found the plug
I was looking for a little plug dangling on the end of a wire......did'nt think to look for a big round plug secured in a bracket fixed to the side of the engine

[DanThe]

[jmc330i]

Just got to get yourself a sensor now then.

[eko]

Just got to get yourself a sensor now then.

Ive got one here if you need it?
Was screwed into the M52 manifold when i got them.
Different connector than E34 tho?

[jmc330i]

Just got to get yourself a sensor now then.

Ive got one here if you need it?
Was screwed into the M52 manifold when i got them.
Different connector than E34 tho?

The M52 will be the 2.8, so the sensor will be different.

The Bosch part number for the E34 525i lambda is 0258003108. You should be able to get one from a decent motor factors with that number.

I got the 2 lambdas for the S50 for less than the price of one from BMW

[Sooty]

According to the ETK, the sensor is specific to the 520 & 525i.
Just checked the GSF site & it's about Ԛ£51.00 for a replacement so it's not too bad.
Will check the local factors in the morning though.

[Brianmoooore]

Only thing specific about it is the plug on the end, otherwise it's a bog standard 4 wire lambda sensor.

[DanThe]

Thats right, I replaced mine with one of a different type of plug, just cut it off and joined on the right plug.
Works fine

[Sooty]

Brian / Dan

Many thanks for that little tip guys.

I've got a pair of 328i sensors here, so I'll hunt around the scrappies tomorrow for a 5 series with the plug still installed & see if I can cut it off (plug itself should only be about 50p).

Cheers

Iain S

[DanThe]

Yeah, a plug is small , it might even fall in your pocket if your not carefull

[Sooty]

You can't be suggesting anything dishonest can you Dan ?

[DanThe]

If it was my local scrap yard the one bloke there wouldnt be very impressed with me chopping a lambda, a mate once went in and asked for a piece from a carb, he said you have to buy the whole carb because I wont be able to sell it with bits missing
Tried to charge me a fiver for 2 pieces of fuel hose once! How I laughed I told him bollocks im off down the Motorparts shop!
Tight bastards wont even let me have the cam cover of a 320 because he thinks someone will buy the engine?

With most places the only way to get a fair deal is to fill a bag and toolbox with decent bits and pay for a jubilee clip
A lot of cars these places have are knackers the council has paid them to remove from the streets

[Sooty]

Know what you mean
TBH, the junkers round here are'nt too bad when it comes to the small stuff.
They've seen me that often that they just wave me through when it comes to plugs, brackets, etc.
There's also the added bonus that it makes a nice change for them to speak to an English person, as opposed to the hordes of Eastern Europeans that seem to have descended on this area like a plague of locusts.

[Sooty]

Found a 520 in the junkers, chopped off the plug & a length of cable, tried to pay but the guy said 'just take it mate'.
Even better, the office girlie (nice figure but a face like a well worn trawlerman's wellie) tried offering me a mug of tea

[DanThe]

Should of asked her if she had a bag

[Sooty]

Sorry to be a pain in the ass but I could do with a little "Guru Guidance" here fellas.

I've got the Lambda plug OK & a sensor from a 328i.

I've checked the wiring diagrams on the ETM but (sod's law ) the wire colours don't match up.

On the M50 plug, I've got:
Pin 1 - Grey wire
Pin 2 - Black
Pin 3 - White
Pin 4 - White again?

On the sensor, I've got:
Pin 1 - White
Pin 2 - Yellow
Pin 3 - Red
Pin 4 - Black

I thought it might be just a simple case of joining them pin for pin, but it's not going to be that straightforward is it ?

Anyone point me in the right direction?

Iain S

BTW Dan - You looking for a 320 cam cover? I've got one sat here on an engine that's going to be weighed in soon. Yours if you want it m8.

[Brianmoooore]

On the M50 plug the 2 whites are the heater, black is grey and black is signal.
You should be able to identify the heater connections of your sensor with an ohm meter. Look for a resistance of around six ohms between two pins. These two connect to the white wires.
For the other two, one way will work, the other won't.

[Sooty]

Cheers Brian

Just tried this on the sensor & I was getting no readings at all from any combination of pins.
Guessed that the sensor was 'fubar'd' so tried the other sensor I have.
Got 5.1 ohms between the red & white (1 & 3).

black is grey and black is signal

This has confused me a little but I'm going to guess that black goes to black and yellow goes to grey.

Many thanks

Iain S

[Brianmoooore]

black is grey and black is signal

This has confused me a little

Iain S

You're confused? I'm confused!!! Fingers don't type what brain is thinking!!!
Try: grey is earth and black is signal

[DanThe]

My wire colours were the same, is it an M50 cam cover Sooty?

[Sooty]

Your confused? I'm confused!!! Fingers don't type what brain is thinking!!!

is it an M50 cam cover Sooty?

Thought it was an M20 one you were after

I can get you an M50 cam cover fairly easily, but it'll cost me a few quid.
Want me to chase it for you?

Iain S

[DanThe]

Thanks for the offer mate but theres plenty by me, its just finding the time and whenever I seem to be near one the thought just seems to completley leave my head as im more interested in something else at the time

[Sooty]

the thought just seems to completley leave my head as im more interested in something else at the time

I suffer from that when I'm near the big breasted one in the scrappies