I need some help. I took my engine out to have all the gasket replaced and to clean it up. After installing I started my turbo build and finally got it done but now it won't crank over. The motor turns over by hand fine. The grounds seem to be good I even put a second main ground on the car. Everything works the radio lights fuel pump and so on. I bought a new starter and installed that because mine was very crusty. It has a brand new battery. Still no crank. I used a meter and was getting 12v at the power going into the starter. but when I turn the key to start on the crank wire of the starter i see 12v for a millisecond then it goes to 8.4 volts and I have no clue. I have read ever post and just can't find the problem so I'm hoping someone here can. Any info would be appreciated. I really want to drive this car again it's been 2 year sadface. I also installed a megasquirt 2 but I read the car should crank over even if you didn't have a ecu plugged in so that can't be it. The wires under the shift boot look like they were cut and spliced from the previous owner. Could any wires there cause this problem maybe I hooked one up wrong? I have a video of me trying to start it ill upload soon. Thanks
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(1) I've had frequent problems with dirty grounds. I would check and the clean every connection on the battery distribution block, the battery ground, and double check/clean the chassis to engine block/motor mount ground.
(2) Check that the unloader relays are functioning properly - for reference https://www.bimmerforums.com/forum/s...circuitry-work
(3) Check the battery. With the key in the start position does the voltage at the battery also read in the 8s - it should stay ~12V? Or just jump the car and see if there is a difference in the voltage seen at the starter. -
Battery is good only goes down to 11.75volts when cranking. Cleaned all my grounds. I did notice the plug under the shifter boot had a brown wire coming out that was going nowhere. I know that's a ground but would it cause the car not to crank? Does anyone have a picture of the plug and wires from under the shift boot? It looks like they cut and spliced some. When I turn the key to crank it I hear nothing. But I hear the relays and fuel pump on the first turn of the key. It must be something stupid I forgot to plug in or maybe something isn't grounded right because I painted the block???? The car ran great before i took the motor and trans out.Comment
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I did try the old ecu. I bought the ms2 used so I thought maybe I got sold a bad unit. but from what I have read the motor should crank even without a ecu in it. Is that true?Comment
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i've honestly never tried but it does seem likely. as far as i know the ecu will not stop a crank but it will shut down spark and injectors if it does not see a rotating engine on start.Originally posted by MrWaffles View Post
have you got an etm? it may help to trace the pathways. grab and save a copy from here : http://wedophones.com/Manuals/BMW/
wouldn't hurt to check the main grounds either including the engine to chassis ground. the etm has a list of where to find them.Comment
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ok I'll check it out thanks for the help.Comment
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Heh. Found my old post looking around https://www.r3vlimited.com/board/for...start-no-crank
More recently i had an extremely weak crank that was caused by the battery/power distribution block (is this the battery or power block?) just been dirty and dusty. Took every single cable off and cleaned and sanded most of the contact points and had no crank issues after that:
Yeah, doesn't seem like the ECU would interrupt anything at all. Nothing else really jumps out at me, especially if you are seeing some voltage at the starter.
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Thanks 4tDX. It's funny because the other day I cleaned that up a little bit but it still had some dust on it. I got the motor to crank over but very very slow and then it stopped. So next time I work on it I'll try and do a better job and maybe that will fix it. I thought maybe it was my ignition switch because at the main wiring harness plug, I wasn't getting any power to pin 18 (black and yellow wire) Could it still be a bad ignition switch. I also had to jump a brand new battery to get it to slow crank.Comment
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