Help with building your Speeduino, installing it, getting it to run etc.
By TurboFob
#67849
Hello,

I'm getting seemingly random rpm spikes to (whats reading as) 10k + rpm. its shutting down the engine when that happens at idle. I'm using the factory wiring from the optical sensor (J925). It occurrs with my factory 4 window cas disc, as well as the 24-1 disc (currently installed). other than that occasional blip or stall, its perfect. Ill add a log where I caught it stalling at idle. I can switch back to the stock ecu and cas wheel and it runs normally with no stalling. From what I gather the optical sensors are supposed to be very resistant to EMI, so I'm not sure shielding the signal is all I need? do I need to do something with pri-, sec+, sec-?

Any help is appreciated.
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By PSIG
#67854
Please post the exact tune used to take the log, so we can correlate settings to actions. If the tune has changed, take a new log. It's easy to keep tune/log pairs together in a ZIP file.
By TurboFob
#67890
PSIG wrote:Please post the exact tune used to take the log, so we can correlate settings to actions. If the tune has changed, take a new log. It's easy to keep tune/log pairs together in a ZIP file.
Right on! here is the log and tune, it hasn't changed.

thanks!

Turbo Fob
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By PSIG
#67899
TurboFob wrote: Mon Apr 08, 2024 3:33 pmI can switch back to the stock ecu and cas wheel and it runs normally with no stalling.
This is common, as the factory engineers know what noise is in their systems, and apply specific filtering in the factory ECM for it. Speeduino has no idea what noise you have.

Keep in-mind, these suggestions are not 'fixes', but to gather clues for approaching the issue. Your log indicates 2 sync losses before you begin the log, and 4 more when it stumbles. Likely a noise issue as there are no other obvious indicators in the log. While you can fight it, such as increasing the signal filtering in TS, we would prefer to find the issue if possible. The catch here is that the factory ECM works, so it's likely a known noise (to the factory).

Only as tests, I would try two things. First is to run with engine protection OFF to see if that function is secondary to causing the stalling with sync loss:
EngProtOFF_test.jpg
EngProtOFF_test.jpg (21.58 KiB) Viewed 263 times

Take a tooth log and composite log of the run. If it looks "normal", use an oscilloscope to inspect the signal for glitches or noise. Also try testing for EMR/EMI noise in other vehicle systems. There are many sources and frequencies of noise, but motor and solenoid noises can sometimes be found with stuff like an AM radio, or an oscilloscope with a short wire as an antenna to sniff for noise sources. Common ones are bad plug wires, cracked plugs, bad blower motors, poor grounds, etc. This part is checking for 'new' noise that the factory ECM is holding ground against, but Speeduino is not yet configured-for and would rather avoid if possible.

A signal conditioner should not be required with optical or other digital sensors. They create a clean 0V-5V signal normally. However, conditioners are often used as a 'filter' device to help clean the signals, when the noise source cannot be found or fixed (always try that first!). If trying a conditioner as a filter, I would suggest a 'smart' version that will help to ignore more noise. The MAX types are good for this, such as the Speeduino Store VR Conditioner, or the MiniMAX-A2 (both are MAX9926-based). Be aware, the filtering can sometimes make the signal unusable (filtering too much), and you're right back to finding the noise source. :?
By TurboFob
#68067
I ran a shielded cable, got a vr conditioner, disconnected every circuit on the vehicle other than the few necessary to run the engine. it seemed like that worked until after 2 hrs of idle it did the same thing. strength of trigger filter makes no difference. (besides start up). I pulled the no2c and inspected it under my scope to make sure i didnt make any assembly error. I updated my firmware, started a new base tune. still the same very very intermittent rpm spike. I did what psig suggested and turned off the limiters and it definitely helped it not just shut off when it spikes but the problem is still there and doesnt seem to be associated with noise. could there be anythig else causing it? I realize from searching this is the most common problem but if every other circuit is off and the signal is clean on the scope, what else is there?
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By jonbill
#68068
I don't think there can be another cause - it'll be noise. RPM is calculated from the elapsed time between teeth. If RPM jumps implausibly, it's because an implausible tooth was seen - i.e. noise.
Best to share current tune and a log with each update post.

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