Any BMW M70 techs here? - PeachParts Mercedes-Benz Forum

LandYaghtLover · #1 07-09-2013, 08:46 PM

Quote:

Originally Posted by BAVBMW

With the injector plugged in, you will have 12v on both sides, and since the injectors are grouped in threes (the DME fires three at a time), even if you unplug one, you'll have power feeding through the others. You'd have to unplug all of the grouped injectors to get an accurate reading. Not sure without looking at a wiring diagram if you can unplug the connector at the DME, since other wires will be included. Unplugging those might upset you readings (particularly if they go to the main relay which feeds the injectors).

Do you have a wiring diagram to look over?

MV

Yes, all injectors are unplugged and wires inspected for damage. If I pull the DME, the voltage goes to 0 as expected. I even clipped a group ground and it lost power telling me wiring is okay from DME to connector. If it still had voltage after being clipped, there would be an issue with wires for sure. And like you said, they are grouped yet all show voltage issues.

This is a pain. I am going to pull the rails with injectors and see if they really fire non-stop.

BAVBMW · #2 07-10-2013, 11:42 AM

Quote:

Originally Posted by LandYaghtLover

Yes, all injectors are unplugged and wires inspected for damage. If I pull the DME, the voltage goes to 0 as expected. I even clipped a group ground and it lost power telling me wiring is okay from DME to connector. If it still had voltage after being clipped, there would be an issue with wires for sure. And like you said, they are grouped yet all show voltage issues.

This is a pain. I am going to pull the rails with injectors and see if they really fire non-stop.

Ok, so with the injectors all unplugged, one wire (red/white/yellow) should have 12v with key on. It does, correct? Injectors 1,3, and 5 (bank one, other side similar) should have a brown/white/yellow wire, while injectors 2,4, and 6 should have brown/yellow/white. Those wires should run to the DME (pins 32 and 3 of X6010 respectively), and with the injectors unplugged, should have 0v. You're saying that with the injectors unplgged, you have either 12v or 7v on those wires? Do you have the ability to remove those wires from the DME connector while being able to plug the rest of the DME connector back in?

Note also that the odd injectors also share their signal wire with the EML unit for that bank, that may be something to look into once you can isolate the wires from the DME.

Voltage to both sides of the injector will not cause the injector to fire, or do anything really. Power on one side, ground on the other will make a fuelly mess of things.

Do you have decent diagrams to work from?

MV

LandYaghtLover · #3 07-10-2013, 10:10 PM

Quote:

Originally Posted by BAVBMW

Ok, so with the injectors all unplugged, one wire (red/white/yellow) should have 12v with key on. It does, correct? Injectors 1,3, and 5 (bank one, other side similar) should have a brown/white/yellow wire, while injectors 2,4, and 6 should have brown/yellow/white. Those wires should run to the DME (pins 32 and 3 of X6010 respectively), and with the injectors unplugged, should have 0v. You're saying that with the injectors unplgged, you have either 12v or 7v on those wires? Do you have the ability to remove those wires from the DME connector while being able to plug the rest of the DME connector back in?

Note also that the odd injectors also share their signal wire with the EML unit for that bank, that may be something to look into once you can isolate the wires from the DME.

Voltage to both sides of the injector will not cause the injector to fire, or do anything really. Power on one side, ground on the other will make a fuelly mess of things.

Do you have decent diagrams to work from?

MV

Yes to the first paragraph. And I did snip one ground at the DME itself to verify that the harness, at least on that one branch, was good. What I may do next is snip all the grounds to see if one ground is the sole issue somehow. Such as in some odd way its getting 12v back onto itself and contaminating the other grounds. if that makes sense.

Have diagrams now. Looking them over. It really must be something simple!

BAVBMW · #4 07-11-2013, 11:46 AM

Quote:

Originally Posted by LandYaghtLover

Yes to the first paragraph. And I did snip one ground at the DME itself to verify that the harness, at least on that one branch, was good. What I may do next is snip all the grounds to see if one ground is the sole issue somehow. Such as in some odd way its getting 12v back onto itself and contaminating the other grounds. if that makes sense.

Have diagrams now. Looking them over. It really must be something simple!

The grounds should be grouped in threes. Can you look over the diagrams and find them all, along with their corresponding DME pins? Do you have the ability to remove individual wires from the DME connector? This would be much preferred over snipping wires, also, it allows for a more precise test.

Are all the injectors/wires behaving the same? It's less likely that something simple would affect four seperate circuits in the same way. Might be a good idea to isolate the four groups of cylinders (1,3,5)(2,4,6)(7,9,11)(8,10,12) and test each seperately.

MV

LandYaghtLover · #5 07-11-2013, 08:39 PM

Quote:

Originally Posted by BAVBMW

The grounds should be grouped in threes. Can you look over the diagrams and find them all, along with their corresponding DME pins? Do you have the ability to remove individual wires from the DME connector? This would be much preferred over snipping wires, also, it allows for a more precise test.

Are all the injectors/wires behaving the same? It's less likely that something simple would affect four seperate circuits in the same way. Might be a good idea to isolate the four groups of cylinders (1,3,5)(2,4,6)(7,9,11)(8,10,12) and test each seperately.

MV

Snipping is almost easier. Actually, it really just is. I have no issue soldering and heat shrink tubing them again.

But I will isolate all groups, test each to 12v+ and ground separately. Then move onto "installing" one group at a time and see what happens. I am leaning back towards a harness issue. I will know more this weekend when I can test things out.

BAVBMW · #6 07-12-2013, 11:16 AM

Quote:

Originally Posted by LandYaghtLover

Snipping is almost easier. Actually, it really just is. I have no issue soldering and heat shrink tubing them again.

But soldering makes for a poorer connection, and is prone to breakage down the road (it doesn't handle vibration as well). Note how few soldered connections you see in cars? And the problems with solder joints breaking as the cars age? See if you can maybe find some 61 13 8 353 746 and 61 13 8 53 747 connectors and the tool to crimp them. Originally for airbag wiring repairs, they're just dang handy.

Good luck this weekend, let us know what you find out.

MV