No Spark. Please help!

[Michael Fief]

I have an 84' 325e, The car will turn over but it won't start. I took out a spark plug and looked at it while my dad turned the car over, no spark. I tested the leads going to the coil and they had 12 volts like they are supposed to, so I figured the coil was bad. After replacing the coil, still no spark. I have checked all the fuses and relays, even the fuse in the trunk coming off the battery. I have checked and double checked my flywheel position sensors as well, I'm out of ideas and could realllllllly use some help. Thanks guys!

-Michael

[craiggroves91]

I have an 84' 325e, The car will turn over but it won't start. I took out a spark plug and looked at it while my dad turned the car over, no spark. I tested the leads going to the coil and they had 12 volts like they are supposed to, so I figured the coil was bad. After replacing the coil, still no spark. I have checked all the fuses and relays, even the fuse in the trunk coming off the battery. I have checked and double checked my flywheel position sensors as well, I'm out of ideas and could realllllllly use some help. Thanks guys!

-Michael

How about the reference pin/tab on the flywheel? What the sensors actually read on the flywheel. It's common for those to break off and inhibit spark.
Other things I can think of of the top of my head is
Bad timing reference sensors
Missing Timing reference on flywheel
Bad main relay
Bad fusible link
Bad DME ground
Bad ignition switch
Bad DME
I'm sure Jlevie might chime in. He is a genius with diagnosing these things

[Michael Fief]

I have read about the reference tab in a couple different threads and I'm honestly just not exactly sure what to look for. I had the flywheel out recently, putting in a new clutch and the only tabs I remember seeing were the ones the pressure plate mounted over.

I just replaced the main relay because I pulled it out, and it was rattling. Figured that wasn't good.. Where is the ignition switch located? Is it the actual barrel of the ignition where the key goes in?

Thanks a ton for your feedback!

[jlevie]

Have you checked for spark at the coil output? If you have spark there, but not at the plugs the distributor or wires could be bad, or the timing belt could have broken.

In no spark at the coil lead, either the DME isn't getting timing data from the reference sensors or the DME isn't running. The later could be a problem with the main relay, fusible link, ignition switch, engine or body wiring, or the DME itself.

[hahaitzskippy]

did you track the problem back piece by piece?

the wires? the dizzy? the coil? missing ground somewhere?

[Michael Fief]

I have checked for spark at the coil lead, and there is nothing. Today I discovered that my fuel pump is not coming on when I turn the key over, it will only come on when I use a wire to jump the two leads where the relay plugs in. Even after replacing the fuel pump relay, there is nothing. From what I've read that sounds like the ignition switch. But I haven't been able to locate exactly where that is, I read somewhere its seperate from the actual ignition barrel but I can't seem to find it.

[craiggroves91]

I have checked for spark at the coil lead, and there is nothing. Today I discovered that my fuel pump is not coming on when I turn the key over, it will only come on when I use a wire to jump the two leads where the relay plugs in. Even after replacing the fuel pump relay, there is nothing. From what I've read that sounds like the ignition switch. But I haven't been able to locate exactly where that is, I read somewhere its seperate from the actual ignition barrel but I can't seem to find it.

or dead ECU !

[jlevie]

I have checked for spark at the coil lead, and there is nothing. Today I discovered that my fuel pump is not coming on when I turn the key over, it will only come on when I use a wire to jump the two leads where the relay plugs in. Even after replacing the fuel pump relay, there is nothing. From what I've read that sounds like the ignition switch. But I haven't been able to locate exactly where that is, I read somewhere its seperate from the actual ignition barrel but I can't seem to find it.

Both spark and the fuel pump are controlled by the DME and only will be present when the DME is running and timing data is presented to the DME from s rotating engine. Obvious suspects in this case are the main relay, fusible link, timing sensors, and ignition switch. If power is present at the coil positive terminal when the ignition is switched on, the ignition switch can be eliminated as a suspect.

[Michael Fief]

I tested the terminals to the coil unhooked from the coil, and they had power. But hooked to the coil, with the key on the meter reads nothing.

How would I go about testing the DME? Honestly, i'm not entirely sure what that is. I'm sorry, This is my first bmw so I am very new to this kind of trouble-shooting. Thank you very much for your help, jlevie!

[jlevie]

If you don't have 12v at the coil positive terminal with ignition on, work back to the ignition switch to find out why.

[Michael Fief]

I have 12v at the coil positive terminal with the ignition on, BUT only when the two terminals are unhooked from the coil. When they are bolted on to the terminals of the coil, with the ignition on the meter reads nothing. Is that normal? Or a problem with the coil?

[jlevie]

That is not normal and indicates that there is a high resistance in the Hot in Run and Start circuit from the ignition switch.

[Michael Fief]

So would the best place to go from there be replacing the ignition switch?

[dustyperez]

what about the fuel or main relay? cuz if the pump works by jumping it sounds like a bad relay

[dustyperez]

also with the key on you should have 12v at both coil terminals, it sparks by grounding it