MS3 Basic 6000 rpm backfire and check engine light
#42
SADFab Destructive Testing Engineer
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Interesting. The only thing wrong with it is there is an extra crank pulse. No idea why, but I'm guessing that it caused the megasquirt to lose sync and basically **** the bed until you restarted.
#45
But how? I'm not saying you're wrong, I'm just having trouble getting my noggin' around it.
Sooooooooooo, everything is going fine and I have a crank angle sensor fail. **** happens. It's like a bad ballast on a fluorescent light. It's not completely dead, but not functioning 100%. I install a new replacement, but it behaves exactly the same way. How can the system that's my engine and electronics suddenly need an adjustment?
I've already made the adjustment, but I haven't taken her out yet.
Thanks much,
Sooooooooooo, everything is going fine and I have a crank angle sensor fail. **** happens. It's like a bad ballast on a fluorescent light. It's not completely dead, but not functioning 100%. I install a new replacement, but it behaves exactly the same way. How can the system that's my engine and electronics suddenly need an adjustment?
I've already made the adjustment, but I haven't taken her out yet.
Thanks much,
#46
But how? I'm not saying you're wrong, I'm just having trouble getting my noggin' around it.
Sooooooooooo, everything is going fine and I have a crank angle sensor fail. **** happens. It's like a bad ballast on a fluorescent light. It's not completely dead, but not functioning 100%. I install a new replacement, but it behaves exactly the same way. How can the system that's my engine and electronics suddenly need an adjustment?
I've already made the adjustment, but I haven't taken her out yet.
Thanks much,
Sooooooooooo, everything is going fine and I have a crank angle sensor fail. **** happens. It's like a bad ballast on a fluorescent light. It's not completely dead, but not functioning 100%. I install a new replacement, but it behaves exactly the same way. How can the system that's my engine and electronics suddenly need an adjustment?
I've already made the adjustment, but I haven't taken her out yet.
Thanks much,
Ideally the sensor is spaced at such a distance that the sensor can pickup an actual pulse at say, 100 RPMs on the starter with a dead battery, and at redline, without the internal circuitry failing to count a real tooth, or, picking up a noise pulse and thinking that is a pulse.
It is possible that your sensor is so close to the crank wheel that a noise pulse (caused by who knows what- crank vibration for example) is enough to trigger the sensor. Moving the sensor further from the wheel will reduce this amplitude, potentially reducing the noise pulse's amplitude enough that it no longer triggers the sensor's circuitry inside to cause it to count that as a tooth.
If moving the sensor further from the wheel solves your problem (if), then you reduced the amplitude of the signal and noise, and the noise reduction stopped the false trigger and hopefully it can still see the actual tooth at low RPMs.
#48
Sir,
Fantastic explanation. I appreciate you taking the time. But you miss my confusification. How could it happen with two different sensors? In other words, what would cause my car to suddenly need a larger crank position sensor gap (if that actually works) than it did before?
Fantastic explanation. I appreciate you taking the time. But you miss my confusification. How could it happen with two different sensors? In other words, what would cause my car to suddenly need a larger crank position sensor gap (if that actually works) than it did before?
#49
I'm having the same issue here. Right at redline WOT pull. Stock ECU was behaving the same way before I installed my MS3. Pulled a code for cam position sensor over retard. Did a new cam position sensor along with a crank position sensor from o'reilys. Might try to go with an OEM crank position sensor and double check the gap. Shouldn't it be fine as long as it's within the FSM specified range for the air gap? I attached a log you will see how RPM drops right at about 6600. Engine doesn't respond to any throttle input until you switch gears and it syncs back up.
Last edited by mzmanny; 04-10-2016 at 02:28 AM.
#53
What else could it be besides a faulty cam position sensor? I've already replaced the crank position with an aftermarket one and the cam position sensor with a new OEM one. I can try another new one? I hear that crank position sensor is a culprit since they are on the same circuit or whatever.
#54
Alrighty then. Since the car was cold this morning, I swapped in the Mazda-provided, Japanese-built crank position sensor. All is well. No dropoff or CEL. She's a beast since the retune.
I hope CARQUEST will take the new defective CPS back. I had to wait for the Mazda part to arrive. The CARQUEST part was in stock. Seemed like the right thing to do to try the box store part. Lesson learned.
Sooooooooooooo, I have Noise Filtering OFF. Should I turn it back on?
Thanks for everyone's time and advice.
poormxdad
I hope CARQUEST will take the new defective CPS back. I had to wait for the Mazda part to arrive. The CARQUEST part was in stock. Seemed like the right thing to do to try the box store part. Lesson learned.
Sooooooooooooo, I have Noise Filtering OFF. Should I turn it back on?
Thanks for everyone's time and advice.
poormxdad
#55
Alrighty then. Since the car was cold this morning, I swapped in the Mazda-provided, Japanese-built crank position sensor. All is well. No dropoff or CEL. She's a beast since the retune.
I hope CARQUEST will take the new defective CPS back. I had to wait for the Mazda part to arrive. The CARQUEST part was in stock. Seemed like the right thing to do to try the box store part. Lesson learned.
Sooooooooooooo, I have Noise Filtering OFF. Should I turn it back on?
Thanks for everyone's time and advice.
poormxdad
I hope CARQUEST will take the new defective CPS back. I had to wait for the Mazda part to arrive. The CARQUEST part was in stock. Seemed like the right thing to do to try the box store part. Lesson learned.
Sooooooooooooo, I have Noise Filtering OFF. Should I turn it back on?
Thanks for everyone's time and advice.
poormxdad
Did you try the carquest sensor with more spacing by chance? What is the new mazda sensor spaced at?
Glad you got it fixed.
#56
I did not. Swapping that part out is an asspain, so I wanted to do it when it was cold.
I shot for 0.045" and got 0.043" when it was all done and tightened up. I'm thinking it won't matter. The CARQUEST part was defective. Interesting how it had exactly the same faulty behavior as the part that was in there before.
If CARQUEST gives me my money back, I may purchase another Mazda part for the spares box.
Thanks again,
#57
Pat,
I did not. Swapping that part out is an asspain, so I wanted to do it when it was cold.
I shot for 0.045" and got 0.043" when it was all done and tightened up. I'm thinking it won't matter. The CARQUEST part was defective. Interesting how it had exactly the same faulty behavior as the part that was in there before.
If CARQUEST gives me my money back, I may purchase another Mazda part for the spares box.
Thanks again,
I did not. Swapping that part out is an asspain, so I wanted to do it when it was cold.
I shot for 0.045" and got 0.043" when it was all done and tightened up. I'm thinking it won't matter. The CARQUEST part was defective. Interesting how it had exactly the same faulty behavior as the part that was in there before.
If CARQUEST gives me my money back, I may purchase another Mazda part for the spares box.
Thanks again,
#59
Gents,
Just had my first chance to drive her with the new sensor after turning Noise Filtering back on. The drop off and CEL is back, but this time at about 6400 rpm.
Are there any negatives to turning Noise Filtering off and keeping it off? I'll probably try a larger gap first, but this really has me shaking my head.
poormxdad
Just had my first chance to drive her with the new sensor after turning Noise Filtering back on. The drop off and CEL is back, but this time at about 6400 rpm.
Are there any negatives to turning Noise Filtering off and keeping it off? I'll probably try a larger gap first, but this really has me shaking my head.
poormxdad