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Need advice from experience for an M42 rebuild

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    Sometimes Ill use a couple sprays of starting fluid to see what happens.

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      do you spray starting fluid in the throttle body assembly when throttle is open?

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        some busy weekends lately but got a chance to try that test that roguetoaster and try to put water bottles under the fuel injectors and try to crank and see what happens. i tried cranking it for a bit and it didnt spray a lot of fuel out. i tried cranking again, then took out the water bottles and its like a few droplets. i put a dry rag and laid it like a blanket under all 4 injectors and cranked again and it's faint discoloration from fuel. like its not spraying, more like trickling? i still get code 1252 doing the stomp test.

        does this mean my injectors are bad? the condition is unknown, i mean when i pulled them out almost 2 years ago when it still was running, then cleaned them before i put them back. could code 1252 mean a bad injector or is it like the wiring for the pulse trigger bad?

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          I believe that code 1252 is caused by an electrical fault where the Motronic detects that not enough current is drawn by the injector(s). The mid-current driver IC in the DME provides a feedback signal to the controller, and the ones for the injectors seem to need to detect at least 1A of current being sunk (IIRC) in order to signal proper function.

          If all of the injectors are barely spraying any fuel, then there is virtually zero chance that this is a fault with the injectors themselves since they are not all going to fail at once. What voltage do you measure at these 3 locations, after putting the key into Accessory-2 position:
          1) At the fuel pump across the power input terminals
          2) At the injectors (if you pull the electrical rail and probe between ground and the terminals for the injectors)
          3) At the power distribution block on the firewall. Not on the large lower part with the ~15mm wire, which is for the starter/alternator, but on the smaller lug above it where a ~5mm black wire connects. This is a separate wire run from the battery which is for the injection electronics.

          If it all reads normal when just sitting in accessory power mode, then you could try #3 while a buddy tries to start the engine to see what it drops to. I am guessing that you are seeing a power brown-out in the injection circuit due to corrosion or fatigue on the ~5mm wire, about 15" forward from the battery where a 50A fusible link is installed on it. It is notorious for seeing failures at the crimp connections and causing really stupid, hard to resolve issues like this. That is, if you have an iS with the battery in the trunk...sedans with the battery under the hood didn't have it.

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            Thanks bmwman91 i will bust out the meter and check on these. i've come this far so i can't give up yet.

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