m60b40 missing, low idle, back firing

[downforce22]

Hate to bring this back up from 2013, but would be nice to have a confirmation in regards to VSS wire.

C6 (green plug on back of the cluster), per ETM is Vehicle Speed Input (shouldn't this be OUTPUT if the signal is going from cluster to DME?) BU/YL.

I am trying to find out what are all the pin/s functions on the C6 and ETM for my car didn't show much other than the BU/YL #6 ? wire.

I stumbled on this thread searching for some info on the blue yellow wire on my s38 swapped car. As I was troubleshooting a light in the cluster, my 86 chassis that doesnt have cruise control, I found this wire connected which is normally a green output wire from cruise control.

Looking at the etm for s38 powered e34 m5 they label the 55 pin outputs and also show input, output, and ground wires. It appears pin 29 on the e34 is the same referenced above as the Vehicle Speed Signal connecting to the Instrument Cluster. It is labelled E as an 'input' which would make sense to be an input to the ECU. It is an Output from the cluster/tach and an input to the ECU.

Jean, you probably already figured this out but not bad to close out the loop.

[Jean]

Hate to bring this back up from 2013, but would be nice to have a confirmation in regards to VSS wire.

C6 (green plug on back of the cluster), per ETM is Vehicle Speed Input (shouldn't this be OUTPUT if the signal is going from cluster to DME?) BU/YL.

I am trying to find out what are all the pin/s functions on the C6 and ETM for my car didn't show much other than the BU/YL #6 ? wire.

[Vtec?lol]

Did you ever hook your ecu to the proper speed signal?

[Vtec?lol]

Sounds like you don't have the correct temp sensor. It should be 14x1.5 threads. Both holes in the coolant manifold are 14x1.5. The e30 DME temp sensor has 12x1.5 threads, which is the one you don't want, since you aren't using an e30 DME. The e30 temp gauge sensor is 14x1.5, which you do want, since you are using the e30 temp gauge.

Temp gauge sensor part number: 12 62 1 710 512 (you want this)
DME sensor part number: 13 62 1 357 414 (you don't want this)

Double check that before you buy anything, but that's what 5 minutes of searching gave me.


Also, that will have no impact on anything other then the position of the needle on the gauge. The DME temp sensor is what impacts drivability.

Thank you so much!
This is the exact info I needed. M42 Temp sensors are 12mm vs the 14mm m20 which is why I've been so confused.
Got my order in! :);)

[JGood]

How did you get your e30 temp sensor on the m60? My threads were too small for the hole

Sounds like you don't have the correct temp sensor. It should be 14x1.5 threads. Both holes in the coolant manifold are 14x1.5. The e30 DME temp sensor has 12x1.5 threads, which is the one you don't want, since you aren't using an e30 DME. The e30 temp gauge sensor is 14x1.5, which you do want, since you are using the e30 temp gauge.

Temp gauge sensor part number: 12 62 1 710 512 (you want this)
DME sensor part number: 13 62 1 357 414 (you don't want this)

Double check that before you buy anything, but that's what 5 minutes of searching gave me.


Also, that will have no impact on anything other then the position of the needle on the gauge. The DME temp sensor is what impacts drivability.

[Vtec?lol]

How did you get your e30 temp sensor on the m60? My threads were too small for the hole

[JGood]

Not to thread jack but, I'm noticing a lot more hesitation and a poor idle after it warms up. Any thoughts? Computer is throwing an o2 relay code

The o2 heater relay may be bad, but that should have no affect on idle quality once the car is warmed up, since the o2 heater only helps to bring the sensor up to temp after starting the engine.

A bad idle and hesitation could be many things... MAF, ICV, coolant temp sensor, etc... Time to bust out the Bentley, a multimeter, and start testing stuff. May also want to check for vacuum leaks, a smoke test is the best way to do that.

[Vtec?lol]

^ same here

Much louder whilst in the e30 though.

Not to thread jack but, I'm noticing a lot more hesitation and a poor idle after it warms up. Any thoughts? Computer is throwing an o2 relay code

[golde30]

my e34 540i/6 with muffler delete made all kinds of crackling noises from the exhaust, but i liked it.

[JGood]

Waaay... late to the party, but...

This sounds like you're running a DME calibration for an auto trans vehicle with a manual transmission.
But as Jonsku said, a light flywheel will have this effect also.

That sounds like the DME isn't seeing vehicle speed and is not engaging DFCO (decleration fuel cutoff). Combustion in overrun is erratic, so OEM's avoid the potential emissions problems by turning the injectors off when the engine is in overrun. If the injectors keep delivering fuel during overrun, you get pops and crackles, which some people like, and can get backfires, which most don't like.


The flywheel stores energy. When you rev the engine up in neutral, it slows back down because the energy you just put into the flywheel is consumed by piston ring friction, pumping losses, oil pump drive power, etc. (all the parasitic losses within the engine).
If you have a lighter flywheel, you store less energy. The same consumption of energy by the engine's internal losses slows the engine down faster.

It takes time for the idle valve to open.
If you're overrunning, the idle valve could be completely closed. The stock calibration knows that it needs to open the idle valve by a certain RPM to prevent stall. If your engine slows down faster than stock, the DME won't have time to open the idle valve enough to prevent a stall.

Crank until the needle stops moving. That point arrives quicker with open throttle.
Did you unplug the DME to prevent introduction of fuel?
Ideally, all cylinders should be within 5%. What you have there is quite good.

Yes, you are a bit late to the party! The issue is resolved, it was a bad tune (aftermarket chip made by a guy on bf.c). Check out the last few posts in this thread. The stalling/hesitation is gone, it's smooth as butter now and 100% drivable as it was from the factory. The backfire on throttle tip-in after engine braking is still there, but every single person I've spoken to with an m60 e30 said theirs does the same thing.

[The Dark Side of Will]

Waaay... late to the party, but...

It seems to be more tempted to shut off if while I'm decelerating to a stop, I don't put in the clutch until the RPM's are below 1500 or so. Almost like it's loading up with fuel as the RPM's are that low under deceleration load.

If I throw in the clutch above 1500 while decelerating to a stop, it will drop to idle, stay there, and coast to a stop no problem at all.

Drove about 2 hours today. Got 100% repeatable results. While driving, if I coasted to a stop in any gear, letting the car engine brake, and the RPM's got below 1500 or so before I push in the clutch, it would then shut off. If I threw in the clutch before it got down below 1500, it would return to idle like normal.

This sounds like you're running a DME calibration for an auto trans vehicle with a manual transmission.
But as Jonsku said, a light flywheel will have this effect also.

Edit: Forgot to add, the backfiring is also consistent now. Any time I'm cruising along, and leave off the gas for a few seconds, then get back on the gas, it gives a fairly loud pop/backfire through the exhaust, it sounds more like a loud crack. Just one. I have no idea what would cause that... but I'm pretty sure it's made more noticeable by the exhaust leaks right after the headers, that's where I hear it the most, right under me. But the people who were in front and behind me on the way to the car meet said they could hear it occasionally as well.

That sounds like the DME isn't seeing vehicle speed and is not engaging DFCO (decleration fuel cutoff). Combustion in overrun is erratic, so OEM's avoid the potential emissions problems by turning the injectors off when the engine is in overrun. If the injectors keep delivering fuel during overrun, you get pops and crackles, which some people like, and can get backfires, which most don't like.

I don't know about that. Motronic 3.3 is well capable of knowing RPM, throttle load, crank and cam position, and of course o2 readings. It shouldn't need to depend on preset values for the time it takes for the engine to rev down. Furthermore, engine braking should be relatively unaffected by flywheel weight... it's dependent on the engines internal compression/friction restrictions vs. the cars momentum.

The flywheel stores energy. When you rev the engine up in neutral, it slows back down because the energy you just put into the flywheel is consumed by piston ring friction, pumping losses, oil pump drive power, etc. (all the parasitic losses within the engine).
If you have a lighter flywheel, you store less energy. The same consumption of energy by the engine's internal losses slows the engine down faster.

It takes time for the idle valve to open.
If you're overrunning, the idle valve could be completely closed. The stock calibration knows that it needs to open the idle valve by a certain RPM to prevent stall. If your engine slows down faster than stock, the DME won't have time to open the idle valve enough to prevent a stall.

I read that you should do ~5 cranks.

EDIT: Just read that the throttle should have been held open while testing. I'm guessing that may have an affect on hold long it took to get up to max psi?

Crank until the needle stops moving. That point arrives quicker with open throttle.
Did you unplug the DME to prevent introduction of fuel?
Ideally, all cylinders should be within 5%. What you have there is quite good.

[JGood]

My swap with hot ass cats still cracks when you let back on the throttle. Just as loud. It did this with my e34 when I took the muffler off. I'm assuming its from the lack of back pressure the restrictive exhaust gives it.

My throttle response is slightly jerky at 2k as well but pulls smooth afterward.

Congrats.

Well, that's interesting. Thanks for sharing, you just saved me the time and money of buying and installing cats! Glad to hear yours is a little jerky around 2k too, I was beginning to think that was another possible problem. The fact that I removed the wedges on my throttle plate probably don't help with that... I'm guessing that's why BMW began installing them.

[Vtec?lol]

My swap with hot ass cats still cracks when you let back on the throttle. Just as loud. It did this with my e34 when I took the muffler off. I'm assuming its from the lack of back pressure the restrictive exhaust gives it.

My throttle response is slightly jerky at 2k as well but pulls smooth afterward.

Congrats.

[JGood]

In any case, I bought a Mark D chip for the car, and it's running better then ever. Still have the exhaust backfire, so I'll throw some cats on it this winter. I may build a 4.4 hybrid as well, should be very minimal work at this point.

Thanks to everyone who helped through this whole ordeal. Can't believe it took a year to get everything sorted. I guess it was a combo of the bad chip from the start, the exhaust leaks causing the o2 sensors to throw codes, and the exhaust backfire which I didn't realize was normal.

[JGood]

You take the speed-signal from wrong place. The INPUT signal to instrument cluster comes from sensor in differential, but you need the OUTPUT signal (e.g. from OBC connector, can be seen in the schematics) from the instrument cluster. To my understanding these two signals are different, which would explain why your DME is not getting it and thus doesn't work correctly..

According to the schematics, that green plug on the cluster is the an output from the cluster. That's where the cruise control gets it's signal, and it's also directly connected to pin 26 on the yellow connector (OBC).




C3 is the yellow connector. C6 is the green connector, and the 3 pins that provide VSS are labeled 'A' on the connector.