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Thanks. That makes sense. The value I reported was the HFM so that's the correct one for this thread then.
So one can plot this measured vs spec'ed values and check if the MAF is healthy (i.e. expect a 45 degree straight line in the ideal case).
Well, I have found that the default map reacts slowly compared to the actual MAF sensor. Sudden changes in air flow are not picked up by the default map, or at least not displayed quickly, it is Alfa-N map and uses TP,RPM,IAT to calculate/display mass air instead of directly measuring it. I have found that actual MAF can deviate quite a bit without setting a code, so use it with a grain of salt.
Just want to share some cool Excel plots you can do from Durametric log for my 3.8. This one is the measured air flow (kg/hr) vs rpm plot.
From the vehicle speed measurements (6 samples per second), assume a weight of the car you can compute the rwhp and torque (measurements were done on almost flat roads).
If you look at the upper envelope traced out by the dots, you'll see that these are pretty close to the IPD plenum dyno plot.
I love these maps !! You can see a couple of "kicks" in there from the ram air tuning at about 4100 and 6100.
Ahsai, what were your temps during the above maps? Can you calculate your VE at 4100 rpm? I have done it and see some serious VE, see what you come up with.
Last edited by Porschetech3; 03-20-2019 at 07:59 PM.
I'll give it a try with the PIWIS when I can - was being held back because my laptop battery has degraded but a new one just got delivered so I should be good to go!
Well, I have found that the default map reacts slowly compared to the actual MAF sensor. Sudden changes in air flow are not picked up by the default map, or at least not displayed quickly, it is Alfa-N map and uses TP,RPM,IAT to calculate/display mass air instead of directly measuring it. I have found that actual MAF can deviate quite a bit without setting a code, so use it with a grain of salt.
Make sense and thanks for the explanation.
Originally Posted by Porschetech3
I love these maps !! You can see a couple of "kicks" in there from the ram air tuning at about 4100 and 6100.
Yeah, I'm actually surprised how good they line up with the stock dyno plot with only a 6Hz sampling rate. Of course we have to take the numbers with a grain of salt because the numbers are very sensitive to my assumptions: 3,400lb and the roads were flat. However, I'm surprised how well the SHAPE match the dyno plot.
If you could do both, that would be great !! Am mainly interested in accuracy, but you are elite in that you have PIWIS, not many people has that. The different bluetooth devices, apps, phones may have problems with sample rate, or spikes, but the data comes from the DME, so the data should be the same, but slow a sample rate will cause it miss the max maf, and a spike will, well be a spike. You can recognize a spike by running a log, the spike will be out of place, slow sample rate can be countered by doing pulls in 3rd gear so that max maf will be available for a longer period of time.
I'll also have to figure out how to get the data! Guessing it will be under DME > Actual Values - keep you posted!
To do logging with Durametric, it's a bit more involved. I'll summarize the steps here:
- Go to DME Actual values
- Check the parameters you want to log (best to limit it to less than 10 or so)
- There's a small tab right above the list of parameter that says logging option or something like that
- Pick "Fast" and "Digital only"
- Save the config file, which remembers which parameters you picked so next time you only need to open this configure file as opposed to manually checking all those parameters again
- Click "Start" to start logging
- When you're done logging, click "Export" and save the log to a csv file
- Click "Stop"
Next time you log, just click recall the same config file and then click "start" to start logging.
I'll give it a try with the PIWIS when I can - was being held back because my laptop battery has degraded but a new one just got delivered so I should be good to go!
That reminds me, I need to order a new laptop battery also, mine went flat last time (I was going to use Durametric to log), before I got out of the neighborhood.
Ahsai's instructions are great for us using Durametric, but you are using PIWIS and honestly I can't remember (Alzheimers?) the steps. Hopefully you can figure it out, or maybe it will come back to me.
Ahsai, what were your temps during the above maps? Can you calculate your VE at 4100 rpm? I have done it and see some serious VE, see what you come up with.
Because I'm "old school" and all my precision Micrometers are USA made! Precision doesn't care whether you use English or metric units, just how well you use them..
3.322in = 84.37mm is that better for you?
Yes and it's better for everyone else that lives outside of the US.
Is your logging showing spikes? Or does it just move up smoothly then smoothly tapers after the max..
It goes up smoothly to MAX then goes down abruptly because usually that's where the redline is and I had to shift up.
Originally Posted by Porschetech3
I love these maps !! You can see a couple of "kicks" in there from the ram air tuning at about 4100 and 6100.
Ahsai, what were your temps during the above maps? Can you calculate your VE at 4100 rpm? I have done it and see some serious VE, see what you come up with.
Intake temp was around 45C and here's the VE plot of my 3.8. You were right about the bump at ~4k and 6k rpm.
Yes and it's better for everyone else that lives outside of the US.
Glad to help out my neighboring countrymen. Here is a handy link to phone app for you and others when we "Mericans" use things like miles, gallons, lbs, oz, dollar, acre, PSI, Fahrenheit ect.
Glad to help out my neighboring countrymen. Here is a handy link to phone app for you and others when we "Mericans" use things like miles, gallons, lbs, oz, dollar, acre, PSI, Fahrenheit ect.
03-20-2019, 06:08 PM
