Recently had some parts installed on my car, new intanke mainfold, m50 injectors, and valves adjusted. everything was running great until i disconnected the battery to install a new coolant senor. connectned the battery and the car started up fine no problem. let it run for 5 mins or so and turned it off. couple days later went outside to go to school and the car would not start. cranked and cranked. and nothing. replaced the 3 main relays, and it feels like it WANTS to start but doesnt. i found out if i disconnet the negative battery cable and then reinstall it the car will fire up right away. ive even drove it around the block a few times. and it runs great, voltage reads 14.0-14.2 when driving. when it doesnt start it reads 11.7-12.0. i put in a new coil and im going to get a new battery tomorrow as well but just cant figure this out at all
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Last edited by 25thh0ur; 12-07-2014, 12:54 AM. -
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sounds like you might have a faulty connection at the battery or cable end. Check the cable ends and connections. Good lucksigpicComment
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Clean your battery terminals and grounds.Comment
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Okay I got new battery cable wires coming in this week I'll try those out. I know my positive cable has a crack in it so maybe that might be it. But it's been the same way since I've had the car for 2 years nowComment
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New battery cables installed and nothing still won't fire up, feels like it wants to but just wont. Once again after cranking th car for a couple mins I disconnected the negative cable and put it back on and the car fired right up no problem.Comment
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Possibly a bad DME (ECU)?1989 635csi - Betty White - 5-Speed, 120k, AWII over Natur Nappa
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How much confidence do you have in the M50 injectors you installed? Were they new or used? When you disconnect the battery cable it resets the DME to the default engine mapping. As the car runs this mapping adjusts to match your particular engine conditions and environment (adaptive mapping). It could be that the new injectors are causing issues with the mapping. I understand that the re-mapping takes some amount time so it may not be what's happening in your case. Worth a shot to reinstall the old injectors and see what happens.Comment
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DME has been swapped. I had the m50 injectors running in my car for about 2 weeks prior to me replacing the coolant temp sensor and the car ran fine. Ever since the sensor was replaced have had problem. Even bought another new sensor to make sure it wasn't that. Totally stumped by this. Replacing the fuel pump tomorrow and I'll report back to see if that's the issueComment
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Is this on the 84 318i? Which of the 3 temp sensors did you replace? Did you get all the harnesses plugged back into the correct sensor?Comment
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I have a m20 swapped into my car now from an 89 325i. I replaced both the temp sending unit and the coolant sensor. Replaced the coolant sensor first and a couple day after it wouldn't start I repalced the temp sending unit. Both in the thermostat housing.Originally posted by vpilarrt View PostComment
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I also replaced the battery this weekend and nothing changed at all. stumped on what it could be, drove it all day yesterday as well and the car runs great and pulls good. one thing i noticed is my windows now take fever to roll up and my volt meter will go from 13.8 with light and radio on down to 12.9 when trying to roll up the window.
here is a update with videos guys and what I'm talking about, first video is with the car sitting overnight from the last time i started it.
this video is when i disconnet the negative battery cable for 5 seconds or so and re connect it the car fires up no problem.
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Anyone?Comment
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The only thing that I think of is to check the ground going into the DME. Wiggle the wire while you check for continuity to the chassis. Aren't you missing a ground wire going to the strut tower?Comment
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Repalced the chassis to oil pan wire couple months back but no I don't have the strutr tower to valve cover one if that's what you are talking about?Comment
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