MikeL
02-22-2006, 10:48 AM
I wrote this up for NYCCDSM:
This was brought up in another thread and I figured I's post how I got my to run great with a MAFT / dsmlink combo.
This applies equally to 1g/2g cars, there are a few requirements, 1st and most important is a way to log airflow (hz), 1g tmo style logger is adequate, 2d ODB2 loggers will be barely adequate because the same rate sucks. If you can swing it, borrow a dsmlink ecu for this. NO BOOST LEAKS! This is extremely important! boost leaks with a stock maf throw off its readings.
To begin, get your car running well with a stock maf, unhacked is very important, run as much boost as you can without fuel cut. (if you have a dsmlink ecu, this will not be a problem). Log airflow (hz), throttle position, rpm, and speed. (If you can, and again have a link, hook up a gm3bar MAP and/or a wideband and log that as well, this will cut tuning time in half).
--Note: If you are NOT using a link, OR an injector compensated ecu, like TMO, DSMChips, Keydiver, etc than you probably want to put 450cc injectors back in and run less than 16psi, if you attempt this with an AFC that is alerting the airflow signal, which is anything but being set at all 0s, it will affect this process).
The more methodical and consistent you make your 2 tuning drives, the easier it will be to calculate the correct curve. Drive around at all throttle conditions, idle, part throttle, cruise, acceleration, and wot. If you can say, idle, pull out of the driveway, cruise to a stop, drive 2-3 blocks normal, then go wot for a gear or two, and repeat the same thing later this will help.
Now that you have your "stock" log check it to make sure you have all the correct data, what you are going to be doing is comparing hz at different throttle/load points comparing what the gm maf outputs vs what stock reads, the stock meter is very good, assuming you have no boost leaks and it is not hacked. If you have a wideband/MAP installed and logged, these values will aid greatly in finding comparable load points to make sure you adjust the correct areas, but we'll go into that later.
Now install your MAFT and sensor, you can get close with a draw-thru setup, I had done that first since it was easier, but my blo-through settings ended up a little different, so if you can, install it in its final configuration. (Only blow through will prevent stalling/part throttle issues).
Now the settings you choose for the MAFT will depend on your setup:
If you are running:
Injector compensated ECU: Set MAFT to 450's setting (this is not all zeros, check the manual for details on your version)
AFC with 660cc or less injectors: Set Maft to 450's, use AFC for correction
>660's Set MAFT to appropriate injectors. For the record, I do not recommend running larger than 660's without an injector compensated ECU. You will be taking out WAY to much airflow and the car will have issues.
Now its time to get the MAFT log
***WARNING***
Installing a MAFT or any airflow metering device can significantly change the amount of fuel, AND the amount of timing your car runs, changes in the wrong direction can lead to engine damage so proceed with caution.
Make the first drive easy, no WOT, drive around albeit, see how the car feels, is it stuttering, bucking, lazy? My car would spit and sputter at first because I hadn't followed the MAFT directions for changing the settings, apparently v2 you need to change the settings in a certain order with power on for them to "take". If you are using a 1g logger, or a dsmlink ecu you can monitor knock and this will give you much better ease of mind when starting to go wot with the car.
Now lets assume you did the same run as before, but without the WOT, get that log and break out the calculator. (Those good with excel can automate this process, but I'm not giving an excel lesson here).
First look at idle, make sure your idle rpm did not change, and see what the hz reading is, it should be 50hz @ 850 rpm (if you have dsmlink, look at the value airflow/rev it should be .27) If it was 50hz with the stock maf, and its now 70hz (this would probably cause idle surge) you would need a -40% idle adjustment I would suggest going 2-3 click leaner on the idle knob for this adjustment, then use an AFC or dsmlink airflow table to fine tune it. (it doesn't have to be exact, I'd say within 5% is good).
Next cruise is the next most consistent reading, try to find a point in the log where there is consistent speed, rpm and TPS. This is probably somewhere between 150-400hz, compare the two from the 2 logs and adjust.
*Note: if you have a wideband or MAP logged double check these values, MAP values will not change they will be used to find similar load points, wideband readings should be compared to airflow, for example if you calculate that you need +10% airflow at 300hz to match up, but the logged wideband value is only off by 3% you may have picked a good sample value.
Unfortunately both the AFC and the MAFT box offer RPM adjustments and not airflow hz adjustments (dsmlink has an airflow correction table), so you will have to adjust by what rpm you are seeing this airflow, which is not the best because at part throttle conditions you can see 400hz at 2000 rpm or 4500 rpm, at part throttle.
Once you have part throttle dialed in, start working on wot, make short pulls, like half a gear at first make sure its reading ok. Hopefully the maft will be compensating on the rich side and you will just need to lean it out.
Just for reference my settings for blow thru (set for 450s, dsmlink set for 850s) are
50: +4 150: 0 250: 0 400: +7 800: +7 1200: +3 1600: +2 2000: -5 2400: -6
This was brought up in another thread and I figured I's post how I got my to run great with a MAFT / dsmlink combo.
This applies equally to 1g/2g cars, there are a few requirements, 1st and most important is a way to log airflow (hz), 1g tmo style logger is adequate, 2d ODB2 loggers will be barely adequate because the same rate sucks. If you can swing it, borrow a dsmlink ecu for this. NO BOOST LEAKS! This is extremely important! boost leaks with a stock maf throw off its readings.
To begin, get your car running well with a stock maf, unhacked is very important, run as much boost as you can without fuel cut. (if you have a dsmlink ecu, this will not be a problem). Log airflow (hz), throttle position, rpm, and speed. (If you can, and again have a link, hook up a gm3bar MAP and/or a wideband and log that as well, this will cut tuning time in half).
--Note: If you are NOT using a link, OR an injector compensated ecu, like TMO, DSMChips, Keydiver, etc than you probably want to put 450cc injectors back in and run less than 16psi, if you attempt this with an AFC that is alerting the airflow signal, which is anything but being set at all 0s, it will affect this process).
The more methodical and consistent you make your 2 tuning drives, the easier it will be to calculate the correct curve. Drive around at all throttle conditions, idle, part throttle, cruise, acceleration, and wot. If you can say, idle, pull out of the driveway, cruise to a stop, drive 2-3 blocks normal, then go wot for a gear or two, and repeat the same thing later this will help.
Now that you have your "stock" log check it to make sure you have all the correct data, what you are going to be doing is comparing hz at different throttle/load points comparing what the gm maf outputs vs what stock reads, the stock meter is very good, assuming you have no boost leaks and it is not hacked. If you have a wideband/MAP installed and logged, these values will aid greatly in finding comparable load points to make sure you adjust the correct areas, but we'll go into that later.
Now install your MAFT and sensor, you can get close with a draw-thru setup, I had done that first since it was easier, but my blo-through settings ended up a little different, so if you can, install it in its final configuration. (Only blow through will prevent stalling/part throttle issues).
Now the settings you choose for the MAFT will depend on your setup:
If you are running:
Injector compensated ECU: Set MAFT to 450's setting (this is not all zeros, check the manual for details on your version)
AFC with 660cc or less injectors: Set Maft to 450's, use AFC for correction
>660's Set MAFT to appropriate injectors. For the record, I do not recommend running larger than 660's without an injector compensated ECU. You will be taking out WAY to much airflow and the car will have issues.
Now its time to get the MAFT log
***WARNING***
Installing a MAFT or any airflow metering device can significantly change the amount of fuel, AND the amount of timing your car runs, changes in the wrong direction can lead to engine damage so proceed with caution.
Make the first drive easy, no WOT, drive around albeit, see how the car feels, is it stuttering, bucking, lazy? My car would spit and sputter at first because I hadn't followed the MAFT directions for changing the settings, apparently v2 you need to change the settings in a certain order with power on for them to "take". If you are using a 1g logger, or a dsmlink ecu you can monitor knock and this will give you much better ease of mind when starting to go wot with the car.
Now lets assume you did the same run as before, but without the WOT, get that log and break out the calculator. (Those good with excel can automate this process, but I'm not giving an excel lesson here).
First look at idle, make sure your idle rpm did not change, and see what the hz reading is, it should be 50hz @ 850 rpm (if you have dsmlink, look at the value airflow/rev it should be .27) If it was 50hz with the stock maf, and its now 70hz (this would probably cause idle surge) you would need a -40% idle adjustment I would suggest going 2-3 click leaner on the idle knob for this adjustment, then use an AFC or dsmlink airflow table to fine tune it. (it doesn't have to be exact, I'd say within 5% is good).
Next cruise is the next most consistent reading, try to find a point in the log where there is consistent speed, rpm and TPS. This is probably somewhere between 150-400hz, compare the two from the 2 logs and adjust.
*Note: if you have a wideband or MAP logged double check these values, MAP values will not change they will be used to find similar load points, wideband readings should be compared to airflow, for example if you calculate that you need +10% airflow at 300hz to match up, but the logged wideband value is only off by 3% you may have picked a good sample value.
Unfortunately both the AFC and the MAFT box offer RPM adjustments and not airflow hz adjustments (dsmlink has an airflow correction table), so you will have to adjust by what rpm you are seeing this airflow, which is not the best because at part throttle conditions you can see 400hz at 2000 rpm or 4500 rpm, at part throttle.
Once you have part throttle dialed in, start working on wot, make short pulls, like half a gear at first make sure its reading ok. Hopefully the maft will be compensating on the rich side and you will just need to lean it out.
Just for reference my settings for blow thru (set for 450s, dsmlink set for 850s) are
50: +4 150: 0 250: 0 400: +7 800: +7 1200: +3 1600: +2 2000: -5 2400: -6