No Start Challenge

[DSpoljaric]

Hi All:

My 81' 733i at 151k is well maintained and has no start issues. Two days ago I experienced that I can crank the motor but it won't fire up.

I took the car to my BMW shop for diagnosis. The shop has run multiple tests, and have determined the all the electrical is operating to spec including the fuel injection system is getting current from the relay. However, when they crank the motor, the fuel injection system power cuts-out, a behavior that one would see when you put in a security code on the OBC - motor cranks but won't fire up.

Although they tested and verified current signal is coming from the computer, tomorrow they will further investigate if the computer itself is at fault causing the behavior as stated above.

Two questions:
1) Anyone have a similar issue and determined root cause?
2) If I need a new computer, anyone have a spare for either trial or purchase? I believe I need #13611272132, AT-Control unit L-Jetronic.

Thanks - cheers

[DSpoljaric]

The shop just called and they have verified that the control unit indeed is at fault and needs to be replaced. If anyone has a 13611272132, AT-Control unit L-Jetronic, please let me know.

Thanks

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Wrong part description and part number stated.

Correct part number:
DME
65811367661

[m735is]

There is a fuse inside of the early OBC box. I can't seem to find a picture of it though. They also can be damaged due to water getting into the kick panel. I'm fairly sure you can find one from another e23, e24 or e28 that also has the early OBC. Just keep yours because there's a code plug on the outside which you may or may not have to swap.

You ask on mye28 dot com for further help on the OBC problem or replacement- lots of help over there.

Edit: Found the picture, I knew it was some where because I posted it:
http://www.bimmerboard.com/forums/posts/512842

[Hit Man X]

Ah yes, that damned glass one. I recall replacing that on my old Ljet 745i. I have a spare box here for my one owner car, I will open and tell you tonight.

Also, see if your '81 has these wires in there - http://www.bimmerforums.com/forum/sh...0#post28573860 If so, you can just reverse the male and female to bypass the OBC circuit. OBC will function as normal, just no security lock out.

[DSpoljaric]

Hey guys, thank you for the replies. The shop was able to bypass wire the starter pin and the car starts and run perfectly. The bypass wire is of course temporary.

Eric, if you have a spare DME that you want to sell, please let me know. Production is 10/1980. I found one candidate on eBay in the UK.

Cheers

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Spoljanic, 46213 004.jpg

[Hit Man X]

That looks like a regular OBC1 box, should be up to 09/84 cars I think.