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Trackday Log Analysis Help

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Hey guys, I just went to a trackday with my R32 GT-R and all in all had a great time!

There were a few issues with the car hitting cuts and the like, so I analysed the logs to see what was going on.

I have attached a log from towards the end of the track day where I tried high boost for a little bit, this made the issues worse.

I also attached the map the car was running at the time.

My analysis is that:

1) I am hitting oil pressure cut a fair bit, especially at high oil temperatures (120-140C)

Accusump is there to help, but obviously I need to resolve the oil control issues.

I might try going from a 10-40 to a 15-50, and add shrouding on the two oil coolers I have, as I don't think they are getting good airflow.

I have an enlarged sump with baffling, so if the above still doesn't help with oil control, dry sump might be the only way forward.

2) Voltage is dropping at high RPM high load, and this is occasionally causing fuel pressure drop.

I suspect that this is a bad alternator, so I have ordered a Franklin Performance LS alternator conversion kit.

The Deka ETX30LA battery is in the boot. The fuel pumps are wired in to the positive cable connecting the battery to the front of the car.

3) I have a PPG sequential, and the ECU was not showing correct gear position (-) when at high RPM.

I was also finding that it was not shifting well, especially on high boost. I guess the ECU not knowing which gear it's in wouldn't help?

The voltage offset is only at +/- 0.1V, so I suspect the voltage issues are skewing the gear position sensor reading. If the alternator doesn't resolve this I may also need to increase the offset slightly? 0.2V perhaps? Unfortunately I didn't have the ECU configured for any gear related logging which was an oversight on my part. I have configured this for next time, and I will be able to use the data to fine tune the gear position voltage values

Looking forward to any help you guys might be able to provide me so that I can take this thing to its full potential!

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Attached Files

Your gear pos sensor not working wouldnt have made a lot of difference in this case since you have basically the same settings for every gear anyhow.

The gear "volt tolerance" on G4+ is a fine balance since it not only determines both the gear index for shift settings at the start of the shift but also it determines when the ecu considers the next gear is far enough engaged to cal the shift complete. Usually on a 6 speed with ~0.6V between gears the sweet spot is around ~0.15-0.20V.

A few other gear shift settings look a bit odd - your upshift and downshift force is quite a bit higher than normal - often more around 60N when using 100N/V. The start shift validation is usually more like 5ms. If you change these settings and do another log I can help you with the shift tuning from there. Log all the gear-related stuff at 100Hz - RPM, lever force, Ign cut, the raw voltage on AN Volt 2, gear shift status.

Is the ecu controlling the accusump valve? I would think you might get more stable pressure if you keep it open all the time. Increasing viscosity is going to help bring the overall pressure trend higher, but it wont improve the spikes low from oil surge. Looks like it is mostly under braking.

Thanks Adam!

Do these logging settings look good?

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Accusump is on Ignition Drive 8.

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DI 2 is starter.

So you are saying for VA 3, I should remove the oil pressure condition, and just make it always open above idle?

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I did think that the shifting force felt quite high! I have pretty sore hands and was starting to get calluses!

Should I try settings more like this?

I also think the sensor is sitting at about -10N with no load, should I adjust the offset until this reads 0N?

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For the Gear pos voltage "AN2 - Gear position" is the only one you need. You dont need ANV2 - Gear pos (status) - this is just whether or not the ANV is in fault mode etc. You also dont need ANV2 - DI or ANV10 - DI - these are only used when the analog input is set up to do a digital function. Log Percentage Ign cut @ 100Hz also.

"So you are saying for VA 3, I should remove the oil pressure condition, and just make it always open above idle?"

Yes, worth a try. I have always only ever worked on cars with the manual valve that you just open by hand before starting. They generally work very well. To me only opening the valve after oil pressure has already dropped significantly is a bit backwards - I have heard of many people doing it, but never seen any data to suggest if it works or not.

"I did think that the shifting force felt quite high! I have pretty sore hands and was starting to get calluses! Should I try settings more like this?"

Yes the high force and long validation time would have made it pretty difficult to initialise a shift. Try those settings I suggested and we will see from the logs if you are getting enough preload. 100Hz logging is actually a bit on the slow side to see enough detail for tuning the shift force but is the best we can do with G4+.

"I also think the sensor is sitting at about -10N with no load, should I adjust the offset until this reads 0N?"

Yes.

Thanks again!

These are my ECU logging settings now, hopefully capturing enough!

You mentioned ignition cut, but the cut mode is set to Fuel % Cut, so I've logged both.

Is it okay to be using Fuel cut for gear shift? Ignition cut would make it go bang between shifts, right? 😁

It's using Ignition cut for the oil and fuel cuts.

Fuel cut for RPM and MAP limits.

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Thanks Adam, this is how it's meant to shift! So much better!

I've attached an ECU log.

As you can see below sometimes the voltage is dropping and this is causing the sensor reading to fall outside the +/- 0.15 volt tolerance.

I figure that I should fix the voltage drop issue (new alternator ordered) before I change the Volt X values too much, as that wouldn't be the correct fix?

Keen to hear your thoughts!