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Experiencing some intermittent sync loss, even with filtering at maximum. Can occur every few minutes (or greater), or sometimes multiple sync loss events within a second. Doesn't seem to get worse with higher RPM, higher electrical draw, vibration, or battery voltage fluctuations. Not sure where to look. Any ideas?


Attached are several logs of the issue and the current tune.

Toyota 1MZ-FE with Speeduino UA4C running 202008 firmware.
Using factory Toyota 36-2 trigger wheel and VR sensor.
Using Speedyefi pre-crimped harness with shielded cable.
Using WMTronics DSC Dual Signal Conditioner for VR conditioning.

Thanks in advance!
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Try a quick test for excess signal amplitude — insert a 5K resistor inline on VR1 input. Anywhere between the sensor and Speeduino. Report results, please.

Background: The input on the DSC was purposely low-impedance for weak systems and low craning speed. On some engines with more powerful sensor output, they can then over-power the input at higher speeds. Yours may be one. Or maybe it's a setting or tuning, but this test is simple. As we have not seen any issues with it not detecting weak signals, we may adjust the impedance up a bit on the design, but you can always add a resistor like described here as well. ;)
Thanks - I'll try the resistor, may take a few days to get results though as the car is undrivable - a wheel bearing failed and I am waiting on parts.

As far as the trigger settings - per the products page "This conditioner is non-inverting, set your trigger to falling edge." - which is how I have it set. The polarity - per the Toyota wiring diagram - is set correctly but I could try it the other way.
Well I added a 5k resistor to the VR sensor - the engine still starts and seems to have a stable crank signal at least near idle.

I did a tooth log as well - the first 2 dated files are before the change, the tooth.csv file is after.
Also attached is a screenshot of the tooth log so you don't need to open the log file.
It seems to be correct to me - I don't see widely varying tooth times like this example: http://speeduino.com/forum/viewtopic.php?p=40981

Maybe it just needs the resistor as psig suggested?
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Ok, I got the car back together and have been testing it after adding the resistor,
The sync loss at higher RPM is now (nearly) gone with only 2-3 events in 30 minutes of driving.
However, it appears that 5k may be a bit much, as I now have occasional bouts of numerous (50 in a few minutes) sync loss events when idling. May try something in between, such as 3k, or a potentiometer so I can adjust it.

Probably going to order a MAX9926 based conditioner as well as the Megasquirt I previously had used that chip without issue.
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