Specializing in the 3g CSM
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PostPosted: Tue Aug 04, 2009 2:47 pm 
Now Drives a hybrid :(
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Joined: Wed Jul 23, 2003 10:47 pm
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Location: Phoenix, AZ
MAF Translator Tuning Guide
Updated: 3/17/04
MAFT Version 2.00+

Please note that this guide is for the tuning of version 2.00+ ONLY! While the same principles will apply for the earlier models, the switch settings and some of the system architecture is different, so the exact directions cannot be followed for version 1.37 and down.

The MAF Translator is a tool that allows you to use the less restrictive GM MAF in place of the stock DSM MAF. Due to the nature of the GM’s hotwire MAF, you can either put the sensor in the stock location, or you can mount it before the throttle body in the upper intercooler pipe.

The setup instructions are included with the product, so this guide won’t touch that topic.

Initial Setup

Before you even start the car for the first time, you need to set the MAFT up. Set the mode 1 and 2 switches to the proper locations for the MAF that you are using (see table).


Set the mode 3 and 4 switches to off for now, until the car has a good base tune.

Using the following table, set the base knob and aux knob for whatever size injectors you are using:


This is not an acceptable long-term solution, but it will be good enough for the car to start and run. If you’re running injectors that are larger than stock, you probably will want to richen up the idle setting a little bit too, to compensate for the higher deadtime. 2-3 clicks is usually a good place to start.

IMPORTANT: Note that the base knob gets leaner as you go clockwise, and the rest of the knobs go richer in a clockwise direction, and leaner in a counterclockwise direction.

Base Knob Tuning

Before you go driving to set the base knob, you may want to reset the ECU, especially if the car is a 1g. This will reset the fuel trims all to 100% (1g) or 0% (2g), and will simplify tuning.

The base settings apply as follows:


Start the car, let it warm up, and go for a drive. You want a nice steady state cruise, 50-70 mph or so is pretty good. Watch the O2 Trim (1g) or STFT (2g), as well as the hi fuel trim (1g) or the LTFT (2g). You want to get both of these as close to zero correction as possible, which means 100% for a 1g and 0% for a 2g. If these read too high, you need to richen the base knob (counterclockwise), and if they read too low you need to lean it out (clockwise). Keep doing this, until the fuel trims are hanging out near no adjustment. On a 1g, you want the O2 trim to cycle around 100% with the hi trim around 100, and on a 2g you want to try to get within a couple percent.

Mid and WOT Tuning

Once the base is set up, then it is time to work the mid and WOT settings. Setting up the mid knob can be a bit difficult, but there are a couple tricks to make it a bit easier. First of all, the mid area will become active as you roll onto the throttle from cruise, until you build a couple psi of boost (approximately 180 to 500Hz of airflow). Roll onto the throttle like this and keep an eye on the STFT/O2 trim, and watch where it goes until the car goes into open loop (when the trim will drop back to 0%/100%). If it rises, then the car is leaning out a little, and if it goes down, then the car is going rich. Adjust accordingly, if possible. On 1g’s, you can also watch for knock.

From there, you go to WOT tuning. The basic premises behind this are simple, but tuning well takes a lot of practice. The basic idea is you want to keep the car from knocking at all, which allows you to run the most timing (and is also safest for your engine, of course). The hard part about this is that timing is related to airflow; the less airflow the ECU sees (because of negative correction on the MAFT), the higher the timing advance will be. You need to find a good mix of boost, timing, and fuel.

Make a full throttle pull through as much of the RPM range as you possibly can. 1g’s are easy, because you can just look for knock and then richen the MAFT up if you see any moderate amount. On a 2g, it’s a little more difficult. You have to base the tuning off the total timing retard. If the timing seems low, you might be getting knock, so try richening up the WOT on click. If the timing goes up, you’re going in the right direction. If it goes down more, then it’s probably low because the airflow is so high, and you can try leaning it out.

WOT Fine Tuning

Note: Do not worry about fine tuning the WOT corrections if you are not confident in your tuning abilities. The car will run fine with only the 4 basic knobs set up.

Also, do not switch to WOT tuning mode, until you have driven around for a few days to get the feel for the basic mode, and to make sure that the fuel trims are in line.

If you are sure both of these two conditions are satisfied, then proceed.

The WOT fine tuning mode adjust the WOT fueling based on 4 rpm breakpoints, as shown below:


It's best to switch from base tuning mode to WOT tuning mode with the ignition off, to avoid any software problems. Also, keep in mind that the MAFT will save your base mode settings 10 seconds AFTER you make any change, so just be sure to give the car at least ten seconds between a base mode change and turning it off. Before switching modes, make sure to record your base settings in case you want to go back and change them later. Switch the mode 4 switch to the “on” position, and zero out all of the knobs. In this mode, the tuning is in 2% increments, and all the points are interpolated.

Using the same methodology as you did for the WOT base knob, tune the four rpm points. Watch the logger and/or wideband O2 meter, and at each point make a distinction as to whether you want to go leaner (and consequently add timing), richer (and take timing out) or stay the same.

Disclaimer: Pulled from the article written by kpt4321@fullthrottletech.com
Archived for informational purposes only, we are not affiliated with fullthrottletech.com.

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