I have a 95 325is coupe that was running great a couple weeks ago. I moved it onto the lawn so it wouldn't get hit by a limb falling during the rain and now I can't get it to start for the life of me. I've changed the fuel filter pretty sure my pumps ok, just changed the spark plugs... it's my only car and I'm very desperate to get it started again. Any help would be greatly appreciated
You are not saying what it does or does not do. I assume it turns over but will not catch (sputter, fire even once, cough, anything?). If this is the case then you could check if it has spark with a spare plug. You can check if it has fuel by removing one of the plugs. Do you have an OBD II unit to check codes or a friend with one?
Battery voltage??
Does the dash light up when you turn the key to the start position?
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Get an old spark plug, remove a coil from the head (you can leave the spark plug in the head) and plug the old spark plug in the coil and hold the spark plug ground to an engine ground (clear metal surface). Then ask someone to run the starter.
Is there a spark?
If yes, then re-install the coil and use some starter fluid (in the intake rubber boot, first remove the MAF) to see if it fires up. If yes (even a little), then there is a problem with the fuel supply: so could be fuel pressure regulator, stuffed filter, dead pump, dead relay or dead fuse. Use a fuel pressure tester (you'll need a T-piece on the fuel rail to test it, be sure to connect it to the fuel-IN hose on the rail, as the fuel-OUT hose has virtually no pressure).
If no spark, then, using a multimeter check if the coils get power when you turn on the ignition. There should be +12V on one of the connector pins of the wiring harness. Set your multimeter to 20V DC. One cable end of the multimeter to the connector pin (try all three of them until you find +12V) and the other cable end to one of the strut tower bolts (perfect ground point).
If you do find +12V, then it means the DME and all the injection electronics get power. Then it's probably the crankshaft position sensor.
If you don't find +12V, then either the DME has died, or some fuse has died, or some relay has died, or there is a problem with your wiring..
Start with this flow chart above, and you should make a big jump in diagnosing your problem..
Also, if while running the starter, there already is some (mis)firing going on, you can skip most steps and probably conclude that there is a problem with the fuel supply (go directly to 2nd paragraph, Spark: Yes)
Good luck!
P.S. If you don't have a multimeter, go buy one right now ($15 should buy a simple one). If you don't know how to use it, watch some tutorials on Youtube. Will be one of your best investments ever, and you can use it on everything electrical. I guarantee it will pay itself back.
P.S. Another easy test is to just disconnect the cable from the MAF sensor. Your M50 should run just fine without MAF, so if the MAF is wasted, and the engine runs fine, you'll know the MAF is fine. If there is no difference, the MAF is probably not the cause.
Last edited by ed323i; 12-13-2018 at 08:07 PM.
1997 E36 BMW 323i (European) 275k km (171k miles), with following small mods:
- Chip tuned DME (190HP/257Nm); 328i dual pipe exhaust (plug&play); Meyle HD control arms, Bilstein B4 shocks
- Fan delete mod: Stock 92C thermostat, 80/88C temp. switch, 80/20% water/coolant; INPA says temps 100% OK
- Throttle body coolant hose delete mod; Comprehensive ASC Delete option list; Solved: -30 additive adaptation values
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