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Dialing in that pesky MAF

Road Tuning

Discussion and questions related to the course Road Tuning

Page 1

Hello all, thanks to raymond for helping me dial in my baserunning airflow numbers! Now I am dialing in my MAF calibration. And I've noticed that depending on how you drive the car you can get quite a bit of difference in your numbers. So with a 4.8l gen 3 ls V8 with a cam, hp tuners 3.xx, and a 4l60e, what is the best way to accomplish this? I noticed in Andre's video he let's everything settle, starts the scan then turns it off at the end of the rev up. I've been doing it as, get on the freeway, let everything settle then start logging and shut it off before I exit. Is this correct?? Or should I let it go through all the gears on the way up to where it goes into power enrichment then stop the log and do it that way? According to my logs, my afr is less than 1% but in just driving around town I noticed my numbers are way different from my logging runs. Should I be concerned with this?

You're always going to notice some variation in your fuel trims based on operating conditions and heat soak etc. That is why the ECU uses fuel trims in the first place. This is also why I suggest not beating yourself up aiming for perfection - It's not attainable and it's not necessary.

To log the data you'll need on the road you can do essentially the same as what I show in the course. It's a good idea to hold the auto in one gear so you don't get any weirdness as it shifts. By varying your throttle and rpm you can fill in the histogram up to the point you enter PE and then stop your logger. Repeat for a WOT acceleration run to fill in the remainder and then rinse and repeat.

I think the key to getting good data is to ensure the engine isn't heat soaked which is a real problem when road tuning. Normally you'll be pulling over to make changes and flash them into the ECU which allows the engine bay to heat soak which can influence your results when you're up and running again. That's why I suggest driving at speed for a few minutes to let everything settle. If you don't do that you'll struggle to get repeatable results and the whole process looks really confusing.

Feel free to ask more questions if you need further clarification.