Originally Posted by Closer_2001

I have the same problems - computer thinks I am waaay lean at idle.

G5X3 on 114. I am convinced it is the overlap throwing air into the exhaust. I kept adding fuel as suggested by most, and the car was PIGGGGGGG!! Rich.

I am playing with it a bit, but I think it is something we will just have to live with.

Originally Posted by txhorns281

Well I certainly am no expert, but the proclaimed "experts" haven't chimed in to anything I had questions about lately. Maybe no one likes me... oh well

BTW, the weather has made crap of my tune...

Originally Posted by 405HP_Z06

I wish I could help. This has been a very interesting thread and I've learned a TON.

The 'experts' don't want to share their secrets with anyone.

Originally Posted by txhorns281

OK... well I'll give this a shot

My Step by Step on MAF recalibration:

1.) Make sure you log Dynamic Airflow vs MAF Frequency (Hz) In HP Tuners it is measured in lb/min so we will have to convert this later for the MAF table (g/sec).
2.) Go do enough driving to log a variety of MAF frequencies. You probably won't get a whole lot of data above 10,000 Hz or below 2000 Hz, but get as much as you can. Cruising on the highway is a good place for this as you can cover all rpms and a wide range of mph.
3.) Save the log run and export the data into a excel readable format and sort the data by MAF frequency (smallest to largest).
4.) Section off MAF frequency ranges that register with the frequency points on the MAF table (IE. For MAF table freq = 3000, you want to use the data you logged in the range of 2940 to 3065) Take the average of all the Dynamic Airflow data in this range. The reason you want to use this range is so that the average is calculated using a sort of "swing error" that straddles the calibration point itself.
5.) Once you have calculated averages for each range (this will be very tedious and take quite a bit of time, but using excel functions makes it much easier) you will have new MAF Airflow data to rebuild the table with. 1 lb/min is equal to 7.58 g/sec so do that calculation and you will derive a new MAF table.
6.) For all the calibration points that you were missing data for (above 10K Hz, below 2K Hz) you can either shoot in the dark and scale up accordingly, or if you choose to log raw MAF air readings in tandem with Dynamic Airflow and frequency, you can calculate the variance b/w your dynamic airflow and MAF airflow and scale up by the trends you see on either extreme. (IE. If as you get closer to 10K and you notice the dyn airflow is 10% higher than the stock MAF airflow, then you can go ahead and "assume" that above 10K Hz it will most likely behave the same, otherwise you could try to log 155+ mph runs )

I know this seems like a very painstaking way to do this but it worked very well for me and using alot of excel functions I was able to reduce the time on this project significantly. I have verified that my MAF reports almost exactly what dynamic airflow the motor sees and therefore does not cause any confusion for the trims (this other bit of business in this thread is not MAF related). Some people have tried using scatter plot functions to derive equations that will supercede any manual calculation, but having to "best fit" the curve for the logged data leaves an element for bias and human error. Manual calculation appears to be the most error free method that I can think of. Hopefully someone can come up with an easier way!

Until then, I will try to make a user friendly MAF calculator that takes the Dynamic Airflow averages you figure out and automatically gives you the g/sec conversion and also the % variance from your original MAF calibration. This will still require you as the user to do a little math and a little inputting...

Originally Posted by Another_User

Well...you have to keep adjusting them with lower values (kind of liek jetting a carb) until you get the right CO (1%) value.

Originally Posted by 98A4LS1

Where did you come up with 1% CO?

Originally Posted by WS6snake-eater

Hey Will the calculator looks good. I'll play around with it a little this weekend and tell you what I think.

Matt

Originally Posted by RedHardSupra

I put together a small writeup and a spreadsheet that hopefully will give people no reason to multiply their MAF numbers anymore, but to actually calibrate it.
It's really simple, plug in your numbers, and you get a calibration, i even formatted it so it's easy to copy it back to HPT
Let me know how you like it.

http://www.allmod.net/hpt/

Marcin

Originally Posted by txhorns281

thanks Matt, we still need to get together ya know?

Originally Posted by txhorns281

maybe they don't have any secrets???