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Thread: SR20VE/Nismotronic AFM Voltage Issue

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Posts: 21-30 of 31
2016-02-01 06:44:25
#21
Hey John, some other stuff ive seen is log files can add the .tcl extension a few times, so you can end up with log.tcl.tcl.tcl, gauge and graph layouts tend to do this too .

Ive also found if i get a Nemu and dont know what base file it has, and try to download without having a base file loaded before hand, the software crashes due to the data from ecu not being compatible with the base file loaded to laptop.
2016-02-02 17:23:16
#22
Looking at the "MAF Voltage2.acl" log, the first WOT occurrence at 6.05s shows the MAF voltage jumping up and down starting at 9.92s. I don't know what is causing this because AFR is holding pretty steady around 15.4. The third WOT occurrence at 26.59s shows pretty normal MAF voltage with AFR leaning from 15.0 to 16.4 and RPM climbing from 1600 to 3800. AFR at idle is very rich at 11.7. Hopefully John can shed more light on what might be happening.
2016-02-03 09:46:54
#23
I've also been having the same problem. I'm running a SR20VE, stock intake and exhaust manifolds, SR16VE camshafts, 2.5" exhaust and 3.5" intake pipe with pod filter, so its a very mild setup. Since I got my Nemu2 in August last year I was mostly trying to figure out why my injectors were cutting out at high load, low rpm. Thanks to Evlnxr, he told me that boost cut was happening. That fixed the injectors shutting off, but I still have the voltage spike causing the MAF load to spike also, and so runs around 8-9:1 AFR that that point. It is very consistent, starting at 1500rpm, peaking at 2000rpm, and returning to normal at 2500rpm. This hadn't occurred at any other point since I've owned the car, and happened as soon as the Nemu was installed. I tried using the ADC2 input for the MAF sensor, but it didn't have any affect on the spike. Also, ADC2 (ADC3 in log?) appears to be another version of my wideband voltage, which is connected up to ADC0. ADC1 in the log shows something unknown, and ADC3 and 4 are different readings of wideband voltage it seems.

However, every other aspect of the Nemu2 I find very good, and the help section has been very useful. It is just this one problem that also I have been having with the MAF load spike.

I have attached a TCD and TCL file for those who are interested in having a look.

Thanks.
2016-02-03 10:09:56
#24
Originally Posted by KevoNZ


...Also, ADC2 (ADC3 in log?) appears to be another version of my wideband voltage, which is connected up to ADC0. ADC1 in the log shows something unknown, and ADC3 and 4 are different readings of wideband voltage it seems.

Thanks.


Oh, this I can shed some light on!

If you have ADC inputs that aren't connected anywhere, they voltage from the channels next to it "bleed" over. To prevent this, you can ground the unused inputs. This will make for a simpler overview in the program. I was also confused by this, but grounding the unused ones were a huge help

ADC naming harmonization is also in the works, so there won't be two ranges (0-3, 1-4) in the future.
2016-02-03 12:43:42
#25
Originally Posted by Dala
Originally Posted by KevoNZ


...Also, ADC2 (ADC3 in log?) appears to be another version of my wideband voltage, which is connected up to ADC0. ADC1 in the log shows something unknown, and ADC3 and 4 are different readings of wideband voltage it seems.

Thanks.


Oh, this I can shed some light on!

If you have ADC inputs that aren't connected anywhere, they voltage from the channels next to it "bleed" over. To prevent this, you can ground the unused inputs. This will make for a simpler overview in the program. I was also confused by this, but grounding the unused ones were a huge help

ADC naming harmonization is also in the works, so there won't be two ranges (0-3, 1-4) in the future.


Ah, thank you so much Dala! I will give this a try
2016-02-11 04:19:12
#26
Originally Posted by KevoNZ
I've also been having the same problem. I'm running a SR20VE, stock intake and exhaust manifolds, SR16VE camshafts, 2.5" exhaust and 3.5" intake pipe with pod filter, so its a very mild setup. Since I got my Nemu2 in August last year I was mostly trying to figure out why my injectors were cutting out at high load, low rpm. Thanks to Evlnxr, he told me that boost cut was happening. That fixed the injectors shutting off, but I still have the voltage spike causing the MAF load to spike also, and so runs around 8-9:1 AFR that that point. It is very consistent, starting at 1500rpm, peaking at 2000rpm, and returning to normal at 2500rpm. This hadn't occurred at any other point since I've owned the car, and happened as soon as the Nemu was installed. I tried using the ADC2 input for the MAF sensor, but it didn't have any affect on the spike. Also, ADC2 (ADC3 in log?) appears to be another version of my wideband voltage, which is connected up to ADC0. ADC1 in the log shows something unknown, and ADC3 and 4 are different readings of wideband voltage it seems.

However, every other aspect of the Nemu2 I find very good, and the help section has been very useful. It is just this one problem that also I have been having with the MAF load spike.

I have attached a TCD and TCL file for those who are interested in having a look.

Thanks.


Thank you for this post.

We are working on a solution that we can get to you guys that are experiencing these issues.

The "problem" here is that the Nissan code implements a "MAX TP" or max load table that limits the overall max TP that the ECU can calculate.

We removed this and instead went with a method that only limits the initial throttle tip-in result for a specified time, after that it is un-capped so to speak.

It seems there is a resonance or some sort of issue with air flow during those RPM ranges that is causing this, because the voltage being reported is correct at the ECU.
2016-02-11 10:36:37
#27
Thank you for your reply. I'm looking forward to the solution
2016-02-11 14:45:56
#28
It only happens when the engine is being heavily lugged. Try lowering the values in the high load,low rpm area of your fuel map where the issue shows up.
2016-02-15 16:49:04
#29
I have a version ready for testing before release, if you guys would be able to test this on your vehicle to ensure functionality that would be awesome.

This should completely fix the issues you guys are having at high low and load RPM.

Email me for the download link and instructions!

@chickford @KevoNZ @Evlnxr
Last edited by JKTUNING on 2016-02-15 at 17-10-11.
2016-02-19 04:37:40
#30
food for thought
Just to give Nismotronic a little bit more info for their fix...

On my g20 with RR engine it came with a vortex measuring type of maf that has a much higher resolution than the older systems. A downside to being more sensitive is that it picks up the engine pulses at WOT:

[img]http://www.dagengine.com/FORUMS/G20_t/FT low rpm.gif[/img]

The same setup and only going part throttle:


Now with t25 and older hotwire type of maf the curve is VERY smooth since no pulses can get to it:
[img]http://www.dagengine.com/FORUMS/G20_t/accel t25.gif[/img]

What is likely happening (and what was mentioned by JK) was that there is a filtering issue at certain frequencies. Possibly similar to below:
[img]http://www.dagengine.com/FORUMS/G20_t/PT to FT notes.gif[/img]

I've had nissans with hotwire mafs a few inches from the throttle body and never experienced this issue. Is it possible you cut out some part of the filtering algorithm or used a turbo bin as a base that might not have a way to handle these pulses in the NA intake?
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