Rev Limit Issue

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HRTuning Fri Jan 10, 2020 4:13 pm

That could be part of the issue, but you can keep an eye on the ELD voltage as well.

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imtheman0313 Mon Jun 15, 2020 5:21 pm

Alright, turns out it was either the MCU in that particular ECU, or the multiplexer feeding that particular data line, has failed. I will diag later. ALTC, speedo, and battery voltage have all returned.

I wonder, has anyone inquired about adding closed loop damping tables to Neptune?
Trying to use closed loop with a wideband is troublesome, at best. The stock O2 seems to be not working correctly (not the sensor, possibly a wiring impedance issue?). It keeps the system centered around 14.2 for some reason. It cycles at the right rates, and doesn't drift at all with different circumstances, just at the wrong AFR.

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HRTuning Mon Jun 15, 2020 7:15 pm

You can adjust the target voltage if it's not staying at your expected target.

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imtheman0313 Wed Jun 17, 2020 12:47 am

Yeah, its set where I need it, but the damping in the stock ECU settings is set up for narrowband voltage swing. So when it tries to adjust 14.5-14.8 (which in narrowband speak would be something like .250-.825V), because the wideband voltage range is much larger, that same swing ends up going 14.2-16.0. I figure it's either because widebands respond a bit slower than narrowbands do, or just that it's damping numbers are not optimized for wideband operation.

I know there's not much room left in the Honda map file for new things, but I'm not sure that it would be a new thing, just allowing the changing of the numbers already in the map? Of course, being pre-OBDII, the closed loop system might be a bit more primitive than I wish it to be. I think the next step is going full standalone, I think Haltech's 2000 series ECUs have all these OBDII parameters built in. My only worry is losing the ALTC/ELD functionality with the standalone. I'm not certain I can simulate that.

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HRTuning Wed Jun 17, 2020 5:38 pm

You said the stock sensor isn't working and stays at 14.2 area. You can change the voltage so it reaches your target.

You can change the wideband voltage output to be 0-1v.

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imtheman0313 Thu Jun 18, 2020 1:41 am

Yeah, for the stock sensor to fuel at my desired cruising 15.2 AFR, it no longer reads any change. I have to set it to a pegged value. I've got a new sensor, and will place it in the collector this weekend (the current deal is on cyl #4, on a cheapy chinese repro header) and see if it makes things any better. I have a feeling that what is happening is the voltage is centered (ie .510V and therefore the most responsive area of the cell) around lambda 1 for the fuel I'm using, which is just standard pump gas. I imagine that newer fuels ethanol content has moved that value to the richer side somewhere around 14.2-14.4 AFR to make lambda 1. I tried setting the stock O2 desired value for what it read when my widebands said 14.8, but all I end up getting is wacky swings, because the sensor is out of its effective range by that point.

I'm wondering if the sensor has actually gone bad, though; hence the replacement and new position. The chinese header has the thing on cyl #4 only, and facing a direction such that moisture can and probably does collect in the sensor body, skewing the readings by some measurable amount. I will update with the results, just in case anyone has the same issue.

But I wonder if the dataset size can accommodate settings for PID parameters? Or is that just another one of those OBDI Honda small map size limitations we've discussed before? I imagine there has to be a software control for that in the map already, it's not something you would want to do with hardware. I guess it's more a matter of, has anyone delved that deep into the code, or do we know what every single bit controls?

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HRTuning Thu Jun 18, 2020 5:56 pm

Could be the sensor.

I mentioned the best way to do it with an aftermarket sensor.

It's a simple cross-over logic. No PID.

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imtheman0313 Tue Jun 23, 2020 2:50 am

Update: The new narrowband reads correctly, so that issue was resolved by placing the sensor at the collector, using an updated sensor type, and replacing the sensor (duh). Now closed loop at idle looks more like I would expect it to, and is centered exactly where the voltage says it should be.

Regarding the wideband voltage issue, AEM has removed that function from the X-Series gauges, so I would have to build a converter. For now, the narrowband seems to be doing the job, so I'll continue being lazy and leave it.

As always, thank you for the back and forth!

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HRTuning Tue Jun 23, 2020 11:41 am

Oh that is interesting. I'm surprised they removed it as a programmable output!

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imtheman0313 Wed Jun 24, 2020 1:20 am

Yeah, I bought two of them before I actually read the manual, lol and realized the narrowband emulator function was gone. I do like the larger display, and the buttons on the front to change the display readout though. The analog output is now a differential output, instead of a referenced one, which is slightly more accurate as an ecu input. I might build a narrowband emulator board myself though. I think I saw one on pgmfi forums a while back.

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