Messages

1

Electrical / Re: Under dash relay ripped out. No tach, fuel gauge, temp gauge or blower

« on: September 08, 2020, 09:40:55 PM »

Well, as usual, basics prevail. I put a meter on the fuses and #10 7.5A fuse looked good but was not transmitting power. Swapped the fuse and all is well again.

2

Electrical / Under dash relay ripped out. No tach, fuel gauge, temp gauge or blower

« on: September 08, 2020, 07:51:35 PM »

So I have a new problem and didn’t know if anybody had dealt with anything similar. 318is 1991. Everything was running good (except my aftermarket radio would go black after a while, though still playing music. Just couldn’t do anything with it. Now it’s dead dead.) A relay fell down under the dash and hit my foot. So I just tucked it back up in there while I was driving. Then when I was backing out of my parking space, the relay (connector and all) fell down and landed on the floor. Turns out when I stuffed it back up there blindly, some wires caught the steering shaft when I pulled into a parking space and ripped 5 wires out. Now I have no power to the tach, fuel gauge, temp gauge and blower motor. I soldered the wires back together and put the relay back in. The relay had 2 brown wires on one terminal, one brown/purple wire to another terminal, one green/white wire on a third and one brown/white on the 4th terminal. But nothing changed after reinstalling it. The tach, blower and fuel gauge work for a second after starting the car but then go out… Any ideas on what I might of fried or how to test the relay? It’s strange to me that they all work for a second but then go out. The fuses all look good, though I haven’t put a meter on them yet.

3

Engine management / Re: does anybody have 1991 M42 DME for sale

« on: September 08, 2020, 07:30:32 PM »

Just an update for anybody that may find this same problem. SO I was messing around with the car again just trying to fix something since I couldn't figure out the idle. So I was working on heat shrinking some of the vacuum hoses to resolve a rough idle. I fixed the cracked hoses that were easily accessible and while cleaning out some leaves that fell  under the hood I noticed a bare wire. Turns out I found 3 bare wires and 2 more just cut off and left. The PO replaced the headlights with HIDs and did a mighty poor job at splicing them in. So I redid all of his connections and capped the extra bare wires(why there are extra I don't know) and Voila! She Runs. The heat shrink fixed the rough idle and not having random extra wires grounding/shorting out the car runs great. ( I also had an early experience with a similar problem early on when I got the car years ago. When I put the left turn signal on, the car would stall. What do you know I found a bad wire contacting the body. fixed and problem solved.) I've put about 1000 miles and its been running great! So short story long, if you have any electrical gremlins, check for loose wires anywhere.

4

Engine management / Re: does anybody have 1991 M42 DME for sale

« on: June 14, 2019, 04:44:25 PM »

The coil primary windings get their 12V supply from the ignition switch, and the DME drivers switch the other end of the primary winding to ground through the T501-T504 power transistors. Low voltage on one coil could mean an internal fault in the coil (and you swapped #3 / #4, and it stayed with cylinder #3 it sounds like), a fault in the driver (which you replaced) or a fault in the S500 IC which drives the drivers (and you tried a different DME so it is not that). That leaves the wire harness. Disconnect the 4 coils and test the resistance between one of the 12V terminals and a ground point.

So I tested the resistance on all of the coils that I have had on the car at some point (7 of them). Most of them were between .5 and .9 ohms.  one was 1.4 (not on the car but taken off because I thought it was bad) and one was 110.2 which was on the car but not on the problem cylinder. I will replace that one with one that has a normal reading and keep searching for other problems.

5

Engine management / Re: does anybody have 1991 M42 DME for sale

« on: June 12, 2019, 08:47:11 PM »

Thanks for the link, i will look that over.

You are correct, I had those coils wrong, that's what I get for not cross referencing the chart I found first on Revlimited. I will have to check the layout when I get home on that one.  While that is an issue, it doesn't clear up the continuity question.

The harness is not plugged into the ECU when checking the continuity,  I have one lead from the meter plugged into the ECU Harness and the other lead checking for continuity on pin 1 in the coil connector to identify them. Then when I plug that coil connector into a coil, leaving the meter lead in the same spot on the ECU harness, I have continuity on pins 2 & 3 on the three other coil connectors (unless I am plugged into #2coil, then there is no continuity on pin 2 or 3 on the other coils).

6

Engine management / Re: does anybody have 1991 M42 DME for sale

« on: June 10, 2019, 08:50:13 PM »

I will have to wait till I get my coils with me at work since my meter is a junky harbour freight one which does not seem to want to measure resistance for me.
While trying to make sure I had everything hooked up right I ran into this dilemma. Let me know if this logic is on track.
to make sure it was connected in the right order I tested continuity from the computer harness to the Coil plug.
Continuity from
pin 24  is coil 3
25 Coil 1
52 Coil 4
51 Coil 2
All plugs off the coils  and testing from the dme harness to the coil plug. But when I connect the corresponding coil plug to a coil I also have continuity on the other 3 coil plugs brown and green wires. Except for one of them.

Pin 24(coil 3)I have good Continuity from the wire harness to the coil plug(#1) with no continuity on 4a(brown wire) or 15(green wire) and when that coil plug is plugged into a coil, I also have continuity on 4a and 15 on the other 3 coil plugs but not on the other three #1pin on the coil plug.

Pin 25 (coil 1)I have good Continuity from the wire harness to the coil plug (#1) with no continuity on 4a(brown wire) or 15(green wire) and when that coil plug is plugged into a coil, I also have continuity on 4a and 15 on the other 3 coil plugs and not on teh #1pin on the coil plug.

Pin 52(coil 4) Same as above

51 (Coil 2) THIS ONE IS DIFFERENT ,I have good continuity from computer harness to #1 pin on coil plug, but when I plug that one into a coil(different coils too) I do not get the continuity on the other 3 coil plugs brown and green wires. 

I assume the one outlier is the one that is wrong but I dont know. Why is there continuity between the ground and the computer harness of the other 3 coils when the 4th is plugged into a coil? Is that normal? or is the one coil that does not have any shared continuity the right one and I have three problems. I can see some logic that there may be reciprocal continuity since it is an interference system, but I really dont know enough about it to know or understand.

The other odd thing is that I'm sure I was very careful in labeling the plugs when I took them off to change the coils. But when I test continuity from the computer harness to the coil plug, they do not line up the same. According to the continuity test, they dont even line up logically the way the harness is assembled. By continuity the 3 and 4 coil plugs are across from each other not next to each other. Which is not physically possible the way the wire harness is assembled. It just isn't long enough. SO I had to move plug wires (I know its not logical but I'm grasping at this point) to correlate and big surprise it runs like the firing order is screwed up. I hope that my descriptions make sense.

7

Engine management / Re: does anybody have 1991 M42 DME for sale

« on: June 01, 2019, 05:59:31 PM »

When I tested the voltage on the coil it was only getting  8 volts. The other 3 were getting 13ish. I tested it at the DME pin and was also only getting 8 volts at the pin.  That is why I tried swapping the driver from another DME that had the same problem. (using the #4 coil instead of 3) and that didn't help. I'm just lost now and I cant find anything else wrong.

8

Engine management / does anybody have 1991 M42 DME for sale

« on: June 01, 2019, 05:25:11 PM »

Hi everybody.
I am looking for a good DME for my 1991 318is. I have purchased 2 of them from ebay and neither solved my problem. I even sent one out to "get repaired" to G7 computers and they told me the damage was in the chip and could not be repaired.  It blows my mind that my original had a problem that one coil was getting low voltage hence only running on 3 cylinders. So i got a replacement, (with no warranty) and the same problem So I tried to frankenstien the two and replace the coil driver but know luck.  It baffled me that it would have the same problem so I tried testing everything I could and found no problems elsewhere. I bought another one and had the same results. Does anybody have one that they know is good that they will sell or lend to figure out my problem. Any other suggestions for repairs are welcome as well.
My original Part #s are  1734060 001 078
Blue Label 0 261 200 175

9

Engine + Driveline / Re: no spark on #2,swap coils around still #2!

« on: December 18, 2018, 08:25:42 PM »

I will have to find some info and test them again. I replaced 1 coil a while ago and it worked fine for about a year. Then i replaced all 4 with Bav Auto high performance coils which worked fine until  this debacle.  (same problem as why i replaced them in the first place) I don't know what I can be missing. Something is apparently frying the coils/computer. I'm lost.
Anybody have specs and process on testing the coils off the car?

10

Engine + Driveline / Re: no spark on #2,swap coils around still #2!

« on: November 21, 2018, 07:43:02 PM »

I don't get it... I picked up a new to me DME from ebay that the seller says "works perfectly". I had a few issues at first with it not wanting to start or then idle. I started playing with the coil connections and I thought I had them connected correctly but I had moved them around so much trying to diagnose things its possible I mixed something up. I finally got them seamingly in the right spots and the car was idling smoothly and reving up fine.  I then let the car idle for about 30 min to warm up and charge the battery since I had not driven it in a long time. I went back outside and then the car was idling and reving like crap. (same symptoms as the lost cylinder from the beginning). I have not put an electrical tester on anything yet because it is now dark and 25 degrees, but I'm getting really frustrated. I don't know what else it could be. It seems really odd that 3 DME's are all bad in the same manner but I can't figure out what else could cause this. 

11

Engine + Driveline / Re: no spark on #2,swap coils around still #2!

« on: November 02, 2018, 10:51:40 AM »

I'm not sure I didn't make a bigger problem but I'm still lost. 
I swapped drivers from the other DME that I had. SO I took out the driver from the other unit from the 503 spot (3rd cylinder?)  I replaced the driver from the original  502 spot which was the dead #2 cylinder.  To my excitement the car started after doing the Frankenstein switch. It ran good for 2 minutes and then same symptoms of a dead cylinder came back. Tested the drivers and the # 2 driver is seemingly working. 13v. now the 501 driver has low voltage (did not do anything with that one) Not only does it have low voltage, the case of the DME is too hot to touch. I got out my noncontact thermometer and the driver heat sink was 185 degrees.
I'M LOST NOW. here is a picture of the drivers https://photos.app.goo.gl/eJHvV9AnhHHB9Zz26 . The 30004 driver is the original. I assume the numbers were manufacture numbers and they were the same since they were both m42s and  they looked the same. Maybe that was a bad assumption on my part.

As I look for replacement DME'S Do only the numbers on the blue label have to match or do the bar code #'s on the white label have to match also. I found lots that end in 131 but mine ends in 060. Do you know the difference if there is one?

12

Engine + Driveline / Re: no spark on #2,swap coils around still #2!

« on: November 01, 2018, 03:14:06 PM »

I think I will try to swap some drivers around. Hopefully it will work and I wont screw more things up. I will let you know how it turns out.

13

Engine + Driveline / Re: no spark on #2,swap coils around still #2!

« on: October 31, 2018, 01:25:46 PM »

So you think that the driver is bad or is something else on the board bad that is supplying the driver with low power?

14

Engine + Driveline / Re: no spark on #2,swap coils around still #2!

« on: October 30, 2018, 10:00:38 AM »

Thanks a lot for the help Dave!!!
So, I reflowed all of the connections for the drivers. Unfortunately it didn't help (on either DME). It will run fine for a few minutes, 10-20 minutes idling or 2-5 minutes of actually driving. It seems to fit the M.O. of failing DME's, running when its cool and then failing once the DME is warm.  I did not see any obvious damage to the driver and did some testing with the  case off to make sure I was getting accurate readings and not a bad connection somewhere. SO I was testing directly on the pin (52) when cold it puts out 14v, once warmed up it drops to 7.5v. I then measured the driver and 3 of the 4 measured at 14v, the one in the "502" (bad #2 Coil)spot was only 7.5v.

So do you think I should take one of the drivers from the other DME and try to remove and replace the "502" driver? They also have different part #s listed on them so I don't know if that determines anything. Or should I just send my DME out somewhere for repair?
Sorry about dragging on the details, but I'm hoping the details might help someone else diagnose down the road.


Edit. I was thinking some more about it and I don't know how it works. Is the center post on the driver a power supply to the driver or a power out to the coil?

15

Engine + Driveline / Re: no spark on #2,swap coils around still #2!

« on: October 24, 2018, 08:12:46 AM »

Thanks for the links and the specifics! I will let you know how it works out.