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Discussion Starter · #1 · (Edited)
Update: Resolved. See posts further down for details.

Cylinder 2 is not firing.

INPA gives a short circuit on fuel injector 2.

Measured voltage across fuel injector pins- 4.78 volts (vs 4.3 for cylinder 1).

All injectors have similar resistance.

Swapped plugs for injector 1 & 2. Injector 2 still shows short circuit. (meaning injector 2 itself is fine). Cylinder 2 runs fine with plug from injector 1 plugged into it. (Surprised this even works actually)

Swapped out battery no resolution.

Anyone have any idea where to start? Have also been having other weird intermittent sensor issues. Wiring going into DME looks fine as far as I can tell. Do these injectors attach directly to the DME? Has anyone ever heard of a DME just failing in a weird way like this? Not a cheap or easy part to replace just to try.

Local hick in the parking lot of autozone where I was diagnosing the issue was insisted that "them there bimmers" have 5 cylinder engines. I guess he was right in my case...

UPDATE: Cause looks to be a leaky thermostat forced coolant water up the wiring harness, into the DME connector where it corroded and shorted a bunch of signal pins together.
 

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If you swapped injectors and still had the same results the problem is not the injector, it is either the wiring or the DME.

Wiring should be pretty easy to figure out??

Test light would be a good thing to have on hand.
 

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Sounds like a DME problem.
Pin 34 on the 52 pin connector on the DME is the input for fuel injector #2.

DMEs are pretty cheap on e-bay, they'll just have to be coded.
 

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Discussion Starter · #4 · (Edited)
Sounds like a DME problem.
Pin 34 on the 52 pin connector on the DME is the input for fuel injector #2.

DMEs are pretty cheap on e-bay, they'll just have to be coded.
Any experience replacing a DME and coding it? Is this something I can do with NCS expert/INPA or am I better off buying a DME/EWS/Ignition Cylinder/Key set off ebay and replacing everything?

I just can't shake the feeling that it seems weird that the DME would just fail. Most people I have read on here who have replaced their DME for some issue have found it not to be the root cause.

Then again since I am measuring a voltage between the two wires on the injector plug it can't be truly short circuited.

I've heard of ground issues wreaking all kinds of weird havoc. The ground wire above the DME looks fine to me. This is where the DME would be grounded correct?
 

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Discussion Starter · #5 · (Edited)
Looks like i can either resolder flash chip from my current DME or replace EWS/DME pair. I have an automatic... I guess this means I need to replace with a DME out of another auto unless I want headache. Maybe its time for that manual swap...
 

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I haven't done it, but recall seeing a number of posts where it was done with the INPA.
I'd rather pay an indy shop to do the coding, than replace EWS, ignition, etc.

Disconnect the ground wire to see if there is voltage on it, I'm not sure, but the DME might be grounding the injectors.
 

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For sure, it's better to get a DME from an auto, but then again, those who did the manual swap, were able to code the DME from auto to manual...

GL figuring out, DMEs are very reliable on this cars. When I had my E28, I carried an extra DME in the glovebox, they are so crappy!
 

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Well a member familiar with our dme claims it to be made of crap. Then again he was tinkering with it like using a soldering iron.

I too have not heard too many stories about our dme pooping out.

If you want the easiest option if you decide to swap that dme, buy a dme ews combo for your country, model, and make sure the dme version is similar. Example, if you got the ms43, don't get the ms45. Yes it would help if it's an auto. Doesn't matter if it was a coupe, sedan, convertible.

Make sure you get as many keys as you can. It's not like you can order one for your car. You'll need to pray there are rogue key programmers like myself who are capable of programming it for you, or worse case scenario, I can pull it off if you send me your ews.

With the key, you can either take that electronic circuit board out (and hope you don't destroy something as long as you're careful) and swap it into your key. That or swap out all lock cylinders which isn't any easier.

Think it over if you really want to do it. Even then you aren't done. More than likely you will have a red tamper dot on because the mileage on your cluster wont match the one on your dme, ews, or the transponder on the key.

Then you have to worry about the settings (aka zcs or vo) not matching what the cluster shows compared to your ews and experience anomalies like settings you are used to changing out of nowhere because your car decided to use the ones set on the ews from previous owners car.

The list goes on and on. Hey at least you might be able you drive it if this assumption of yours is correct
 

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Discussion Starter · #9 ·
Well a member familiar with our dme claims it to be made of crap. Then again he was tinkering with it like using a soldering iron.

I too have not heard too many stories about our dme pooping out.

If you want the easiest option if you decide to swap that dme, buy a dme ews combo for your country, model, and make sure the dme version is similar. Example, if you got the ms43, don't get the ms45. Yes it would help if it's an auto. Doesn't matter if it was a coupe, sedan, convertible.

Make sure you get as many keys as you can. It's not like you can order one for your car. You'll need to pray there are rogue key programmers like myself who are capable of programming it for you, or worse case scenario, I can pull it off if you send me your ews.

With the key, you can either take that electronic circuit board out (and hope you don't destroy something as long as you're careful) and swap it into your key. That or swap out all lock cylinders which isn't any easier.

Think it over if you really want to do it. Even then you aren't done. More than likely you will have a red tamper dot on because the mileage on your cluster wont match the one on your dme, ews, or the transponder on the key.

Then you have to worry about the settings (aka zcs or vo) not matching what the cluster shows compared to your ews and experience anomalies like settings you are used to changing out of nowhere because your car decided to use the ones set on the ews from previous owners car.

The list goes on and on. Hey at least you might be able you drive it if this assumption of yours is correct
I've got an AK90 (never used it yet) so I think I should be fine there. There is a seller on eBay selling DME/EWS combo with two paired uncut keys, so I am thinking that is the way to go.

Just am worried that this is not the issue. Hate going to the effort to swap out DME if this isn't the issue.

"Disconnect the ground wire to see if there is voltage on it, I'm not sure, but the DME might be grounding the injectors." -- the voltage across the injector harness is 5V. I am assuming the connections that are all tied together go to a sensor ground on the DME? They don't seem to have a connection to actual ground...
 

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Discussion Starter · #10 ·
Bump for any last opinions before i try swapping the dme:thumbup:
 

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Discussion Starter · #12 · (Edited)
Well, who wants to play a game of "What is that green **** in my DME connector?"

Only on one connector.

Untitled by thefrog1394, on Flickr

Untitled by thefrog1394, on Flickr

Untitled by thefrog1394, on Flickr

Looks like Pin 34 is snapped right off the connector. Too bad I didn't investigate this months ago when I started having issues. Maybe I would have been able to salvage my DME just by cleaning the connector out.

Now to figure out what happened here to make sure it doesnt happen again. Looked like some possible dampness at the bottom of the computer compartment. Seal looked fine on the lid, so not sure where water would have made its way in.

My DSC controller has been giving some sporadic sensor errors as well. That connector looks like it will be quite a pain to get to. Hmm.
 

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Corrosion from some sort of contamination.

Most likely a liquid.

Now, here is the thing you have to think about, how would contamination have gotten into the connector?

Believe it or not you may have a sensor on the engine, likely in the cooling system, that may be leaking and coolant may have wicked its way back to the connector via the wiring.

Keep a very open mind here, see if you can determine what wires/sensors connect to this connector and if any are for the cooling system.

Another possibility depending on the connector location, rodent damage from urine.

You might get the car running well for a while until you can solve the root cause of the problem by cleaning up the corrosion.
 

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Discussion Starter · #14 · (Edited)
Corrosion from some sort of contamination.

Most likely a liquid.

Now, here is the thing you have to think about, how would contamination have gotten into the connector?

Believe it or not you may have a sensor on the engine, likely in the cooling system, that may be leaking and coolant may have wicked its way back to the connector via the wiring.

Keep a very open mind here, see if you can determine what wires/sensors connect to this connector and if any are for the cooling system.

Another possibility depending on the connector location, rodent damage from urine.

You might get the car running well for a while until you can solve the root cause of the problem by cleaning up the corrosion.
Hmm. Thanks for the response. I definitely have a severe oil leak from the valve cover gasket, but that would have inhibited not caused corrosion. Updated my previous post with a few more details.
 

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Discussion Starter · #15 ·
Smells a little bit sweet like antifreeze, but I could just be imagining that.

Any ideas on a way to replace that broken pin? Hate to swap an entire dme just because a single pin broke.
 

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Discussion Starter · #16 · (Edited)
DME Connectors pinout

What do ya know? A bunch of the sensors I've been seeing intermittent issues with in the past.

Coolant temperature sensor signal/ground, thermostat are the two cooling system items on here. Do you really think coolant could work its way from the coolant temperature sensor up an entire wiring loom? That seems nearly impossible to me...

Would plain water produce green corrosion like this? IDK how it would...
 

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Here is the overall problem, IF the problem was due to a bad sensor and coolant worked its way from a bad sensor to the DME via the wiring due to the capillary effect, then you really have to solve the root cause of the problem.

This means you must replace the faulty sensor, and you MUST stop the capillary problem. This means replacing the wiring harness or section of harness that is impact to do the job properly.

You might be able to do somewhat of a hatchet job as well. Not 100% how well this would work, but it should. Either run a new wire/wires from the sensor to the DME connector outside or along the wiring harness or just the contaminated wiring and splice a new section of wire using a soldered splice connection. The solder will not be well received by many, but what are your options. The solder will create a full physical barrier and the break in the insulation should make it very hard for any more coolant to work its way from the old wiring onto the new wiring.

Again, this assumes a slightly leaking thermostat or temp sensor was the source of the problem to begin with? It could be fuel or oil as well? But now that you what sensors/connections are tied to this DME port you can start to look around. I would expect you should see something unusual at the defective part once you trace this down assuming the liquid worked its way though the wiring harness.

To answer your question about can you fix the broken DME pin, well no really but you could put a bypass wiring in it somehow. You need to buy time and get the car running. You might be able to open the DME, solder a jumper wire on the inside and get it outside of the DME then splice the wire into the harness beyond the connector. Not a good or pretty repair, but again it may by you time so you can start to figure out how you want to permanently repair the problem.

Time to start at how hard a wiring harness swap will be and figuring out 100% the source of the problem. How did the car get to this point, if you cannot figure out how this happened, you are nowhere closer to a resolution.

As for the green being caused by plain water, not 100% sure. What happens is moisture of some sort gets to the point where there is enough and any soft of contamination, even a slight bit of dust or something else will act ask an electrolyte once Voltage is present, kind of an electrolysis situaiton will happen.The green is likely from the copper pins and the copper being dissolved/transferred in the presence of an electrical current. Usually the black, most corroded or the pin that broke is not the source of the liquid but the source of the strongest Voltage or current. It could also be the source of the liquid but not always. Again, you have to figure out the source of the contamination, solve that problem and them clean you the path of the contamination.

Good luck to you on this on, sux to be you in this situaiton as this is not really a simple but painful DME swap, it may be a DME, wiring harness and sensor swap?

Keep us up to date on what you find out, hopefully this is not a common occurrence or new E46 "feature"!
 

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Discussion Starter · #19 ·
Thanks for the links!

Sounds like consensus is that it is likely the thermostat. I'll check the wiring myself to be sure. Anyone who has weird electrical issues in the future, make sure you check your DME connections! Don't wait for possibly irreparable damage like I did!

Some good excerpts:

"The root cause of my problem was the thermostat leaking water into the connector, which wicked up the signal wires to the DME sockets, filled them with water, and shorted out the throttle body."

"Had the car towed to local trusted guy and he diagnosed leaking thermostat that ran down wiring harness and corroded the DME"

It took them 2 hours to figure out that "the thermostat melted, coolant leaked onto the DME and short circuited it.

"Had an issue six weeks ago on the way home with massive loss of power and stalling constantly. Took the car to the dealer who (eventually) found the thermostat had forced water back down the waterproof wiring harness protection and on to the DME pins which had corroded and snapped the pin for the inlet camshaft sensor. "
 

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Yep V-8's have had this issue for years. I've seen oil in the glove box on an old E-30 years ago. Oil pressure switch was leaking and the oil pushed all the way to the control unit. Sometimes they actually seal the harness too well.
 
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