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-   -   No start - "weak" spark, no codes, new crank position sensor (http://www.318ti.org/forum/showthread.php?t=45019)

tiRally 04-17-2021 08:51 PM

No start - "weak" spark, no codes, new crank position sensor
Hey all, A month or so ago when I tried starting my '98 ti, it fired a few times then nothing but crank. No codes were thrown. I've tried the following so far:

1. I sprayed carb cleaner into the throttle body, no difference.
2. Tested plug #1 and no spark
3. Checked DCM compartment, dry as a bone
4. Replaced the coil pack, no difference, returned it.
5. Replaced the crank position sensor (VNE, NOT genuine BMW); cranks but doesn't fire (my poor flayed hands :frown:)
6. Tested plug #1 today and recorded it (below)- it sparks brightly every few seconds but that's it - car still cranks but doesn't fire.

From what I understand, since it's sparking it's not the computer. What should I try next? Test the relays? Test fuel pressure? Compression test? Test the fuel pump? I can turn wrenches but I'm not much good with testing electronics.

I'm confused as to the change in sparking with no improvement after replacing the CPS unless the CPS and something else went bad simultaneously (or the CPS is junk). Any help is appreciated!

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J!m 04-19-2021 02:19 AM

Check for corroded ground leads.

If it’s not simple, you have to go back to ground zero and check everything...

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