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Are my coils failing?

Old 09-27-2015, 11:14 AM
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Default Are my coils failing?

Ok, so I finished up my MSM Swap into my 99, The tune is looking a LOT better and was running a lot better. I have a DIYPNP MS2. Here lately, the engine wants to die. And by that, I mean the Tach drops to zero and I lose power. The lights, radio and everything else stay fine, but the engine feels like it wants to shut off. At first it was just random, during my 125 mile commute. Then it was whenever I went into boost... Now it is pretty much any thing about 3k RPMS.

If I let the car cool down completely, it will run ok for 30 or so minutes.

When it dies, I can usually push in the clutch, it will backfire, then start back up. Sometimes I have to downshift and left off the clutch before it will.

I have also noticed a sound under the dash when this happens, That could be described as either a relay kicking on and off really fast... or maybe arcing.

I have checked my grounds and all wires. Everything SEEMS to be good. I pulled the ECU apart last night and could see no signs of Carbon arc traces.. everything on it tested ok as well.

My MSM motor is completely stock, except for an airbox and MAF delete. It has 44k miles on it.

Thanks!
Randy
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Old 09-27-2015, 11:46 AM
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Crank or cam sensor going out. Check with the composite logger. The cam sensor is the one that fails more often.
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Originally Posted by ninerwfo View Post
The “into to megasquirt thread” mentions that the MS3 basic has 5 inputs with built in pull up resistors - and I was just wondering why it would have so many, while the MS3Pro PnP has just 2 (with no pull ups?)
MS Labs: Plug and Play Megasquirt ECUs for ANY 90-05 Miata (NA, NB1, NB2 w/VVT, MSM), including basemaps to get you started ASAP. PM me or email or details.
For support on MS Labs ECUs: Please email, be sure to include the unit's serial number and include a datalog and your current map.
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Old 09-27-2015, 05:00 PM
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Originally Posted by Reverant View Post
Crank or cam sensor going out. Check with the composite logger. The cam sensor is the one that fails more often.
I just so happen to have a spare of each. When it died and I had the comp. logger running, the logger just went blank until it came back up.
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Old 09-27-2015, 06:15 PM
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bad ground it sounds like to me. I'd get out a multimeter and start checking them. Also remove and clean them all, and check the wiring diagram to verify you didn't miss one.
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Old 09-27-2015, 09:22 PM
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I've been over all the grounds. Everything seems to be good there. I did not get a chance to swap the sensors out today. I will try them tomorrow.
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Old 09-28-2015, 08:39 PM
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Ok, today I replaced the Crank sensor and went to the store. Within a few minutes, it was acting up again. Dying and tach goes to zero. SO I pulled over and swapped the Cam Sensor for a new one. Immediately the problem went away and has not come back as of now!

So Thank you!!! I never would have suspected those as the culprit. Every time I have had one go, the car has just refused to start.
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