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Old 02-08-2015, 12:15 AM   #1
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Default DIYPNP MS2 intermittent Spark 1990 No start

Don't know if I ever posted here, I saw some similar issues to mine, but not quite, so I thought I would ask. I'm Rick BTW, Hi.

OK so I have a 1990 1.6 T3 DIYPNP MS2 Microsquirt car stock coils. got it going around June while still being mostly a complete noob. Tuned it with the on the fly autotune. Car ran great until the other day until it died on the freeway suddenly (RPM's dropped to 0) Got it in a parking lot and wouldn't start.

Next day I get lucky and it starts with the autotune (after cranking like hell) First minute or so, lots of sputtering (RPM's occasionally dropping to zero) but once warm it smoothed out and ran great all the way home. Started back up fine when hot, but now that its cold it is having the same issue.

-So far I know the car gets plenty of gas and runs great off the stock ECU. when I pull the plug it will spark intermittently and sometimes not at all. the laptop reads RPM's but it's not consistent when cranking.

Also, the spark map I used was off of the megasquirt site and the "test car" had Toyota ignition. I'm on the stock coils, thing ran great though for about 5K miles

Anyways, thanks couldn't of done it without this site. Anything would be much appreciated.
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Old 02-08-2015, 08:01 PM   #2
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Sounds like you have a problem with your tach signal input to the DIYPNP. No spark (and fuel) is a result of lack of tach signal. 0 RPM = 0 Spark.

Most likely this is a bad connection somewhere between the CAS and DIYPNP. A composite log may narrow things down a little as to which CAS signal is flaky. You should check over every wire and connector between ECU and CAS. Also check solder joints and jumpers inside the DIYPNP, especially pertaining to the Opto and VR2 inputs and their pullups.
It is also possible that the CAS itself is on its way out, though a bad connection somewhere is a lot more likely.
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Old 02-09-2015, 11:08 AM   #3
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Right on Ben thanks for the reply. I think instead of the long story I probably should of just asked what runs the actual spark/tach signals on the board. But writing the story helped me narrow it down a little in my head.
Probably mess with it tonight.. I'm thinking its something simple myself like a solder joint.
Thanks for reading that whole mess though.
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