Tuning Tips

Raising the Thumbwheel position up from position 1 will give about 3% more duty cycle fuel per position. Find the position that supplies the desired amount of fuel for the amount of boost you are running. Keep in mind that after 4000 rpm the fuel does not follow the boost up. Initially, in first gear, the program follows the Spool Fuel curve which is operator selected. At about 5100 to 5400 rpm's (Depending on the chip version), it switches over and goes by the WOT fuel loaded into the thumbwheel position you are running on. When car is running, the thumbwheel position does nothing but control the wide open throttle fuel. If you short shift 2nd gear by not reaching enough rpm's to trip you out of the spool fuel mode, a timer will time out tripping you out of spool fuel and onto the thumbwheel position fuel. It will then stay on the thumbwheel position fuel for the rest of the run until you let off the gas, which resets spool mode (Less than half throttle).

This doesn't sit well with dyno's sometimes so keep that in mind. You want the rpm's to come up into the 5000's pretty fast like when launching in 1st gear.
Later versions of the R mafless have a spool fuel disable function.

Always start high on the thumbwheel position. If too rich at wide open throttle, the car will fall flat when at the top of first gear or in 2nd. Come down on the position or up on the boost.
Once you get the boost where you want it, tweak the WOT fuel in with the thumbwheel position.

A wide band is handy for tuning and most fast guys like to see 11.0 to 11.7/1 FA ratio at WOT

EGT's are handy as well but can fool you when gas burns in the exhaust due to over rich and or not enough timing. This drives the EGT artificially high.
When things are right and C-16 gas or equal is used, people tend to shoot for 1600 or more degrees EGT

On pump gas and alcohol, you will probably observe that the car may mph higher with lower than typical EGT. Some applications like more fuel as the motor heats up.

This brings us to the X factor adjustment (Certain Versions). Cars with aluminum heads seem to run stronger in the 1/8th mile when leaned out. Conversely, the mph seems to drop out at the end of the 1/4 when set leaner in the 1/8th. With X factor you can run leaner in the 1/8th by selecting a lower thumbwheel position than you normally run for best 1/4 mile mph. Then, you can throw X factor fuel to it at, or around the 1/8th mile mark to make it act like it is running on a higher thumbwheel position. Pos F has the time in seconds the X factor enables (e.g.:: 72= 7.2) seconds and position B has the amount of fuel applied. 15 numbers in B will bump the fuel about 3.5% duty cycle which is roughly about the same as running on 1 number higher thumbwheel position.

1. Make sure your scan tool is hooked up and running correctly (See Scan Tool Info at bottom for more info.)
2. Select a thumbwheel position and verify on your scan tool that the position matches that on the thumbwheel.
3. Motor off key on, set E brake and pull into drive.
4. With the A/C set to OFF, depressing the gas pedal will add 1 number to desired function. With the A/C ON, depressing the gas pedal takes away 1 number from desired function.

When engine is running, the programming mode is disabled. You may not have to do any programming, as the defaults may be very close.

Initial programming sequence (Engine off, key on) must be in this order :

1. Pos 0, Hot Drive Idle. Go down until the motor trys to stall when put into gear or the RPM's do not recover very well to the desired RPM in drive. Should be 900 in park and 850 in drive. Usually it will go to 775-800 when put into drive and recover quickly to 850. Give it just enough numbers in pos 0 to idle well when hot, and put into drive, then add 1 or 2 more numbers and call it good.
   
   
2. Pos E, Park Idle. Go Up as a rule until the motor doesn't idle well in park, then go down a tad. More numbers are leaner. Leaner is better here.
   
   
3. Pos 1, Tip in. Never go higher than 3. Usually anything between a 0 and 3 works well here. Default is 3, don't go any lower than you need to for a snappy response.
   
   
4. Pos 6, Off idle fuel. This takes over for idle fuel when throttle is cracked. This is base fuel offset, affects everything including WOT fuel.
   
   Leaner is meaner. Siemens injectors can tolerate a very low number here for best low end response and economy. This is an important adjustment. Always try to move this down below 10.
   
   
5. Pos 5 Cruise fuel. Set as low as possible until you experience difficulty at cruise, such as hesitant response and stock 02 numbers dropping all the way out. This is for steady speeds . Set for stock 02's in the .030 to .080 range at 65mph. Enables at 33 mph and is good to about 1/8th throttle.
   
   If you aren't currently running an O2 sensor, temporarily put a stock 02 in for this adjustment, then take it out if you want. OR, if no 02, lean the cruise until you have trouble at a steady speed then go richer a little bit until the problems are resolved.
   
   
6. Wide Open Throttle Fuel. When car is running, the only difference between positions is the wide open throttle fuel. Each position up from pos 1 gives about 3% more duty cycle after 4000 rpm's. If it revs fast in 1st gear and falls on it's face at the top of the gear or in 2nd, You are probably too rich and you need to cut back on the position. You can also raise the boost to lean it out.
   
   After 4000 the fuel does not follow the boost, you need to pick the position that supplies enough fuel at WOT. A wide band 02 sensor is optimum for tuning. When you raise the boost, the fuel will lean out as mentioned, keep that in mind. It is advised to set the boost and start rich on the position. Then, come back on the position until the desired fuel air ratio is achieved. Keep in mind that the motor initially is in spool fuel mode and doesn't go "on the thumbwheel" until after the first time to 5200rpm or so.

Note: This version does NOT require a position 0 reboot. It can be booted on any position. Also, the programming functions have been re-arranged to line up with Direct Scan cells making it easier to understand.

Initial programming sequence (Engine off, key on) must be in this order:

1. Pos 5, Hot Drive Idle. Go down until the motor trys to stall when put into gear or the RPM's do not recover very well to the desired RPM in drive. Should be 900 in park and 850 in drive. Usually it will go to 775-800 when put into drive and recover quickly to 850. Give it just enough numbers in pos 5 to idle well when hot, and put into drive, then add 1 or 2 more numbers and call it good.
   
   
2. Pos D, Park Idle. Go Up as a rule until the motor doesn't idle well in park, then go down a tad. More numbers are leaner. Leaner is better here.
   
   
3. Pos 6, Tip in. Usually anything between a 0 and 5 works well here. Default is 5, don't go any lower than you need to for a snappy response.
   
   
4. Pos 8, Off idle fuel. This takes over for idle fuel when throttle is cracked. This is base fuel offset, affects everything including WOT fuel.
   
   Leaner is meaner. Siemens injectors can tolerate a very low number here for best low end response and economy. This is an important adjustment. Always try to move this down below 10.
   
   
5. Pos 3 Cruise fuel. Set as low as possible until you experience difficulty at cruise, such as hesitant response and stock 02 numbers dropping all the way out. This is for steady speeds . Set for stock 02's in the .030 to .080 range at 65mph. Enables at 33 mph and is good to about 1/8th throttle.
   
   If you aren't currently running an O2 sensor, temporarily put a stock 02 in for this adjustment, then take it out if you want. OR, if no 02, lean the cruise until you have trouble at a steady speed then go richer a little bit until the problems are resolved.
   
   
6. Wide Open Throttle Fuel. When car is running, the only difference between positions is the wide open throttle fuel. Each position up from pos 1 gives about 3% more duty cycle after 4000 rpm's. If it revs fast in 1st gear and falls on it's face at the top of the gear or in 2nd, You are probably too rich and you need to cut back on the position. You can also raise the boost to lean it out.
   
   After 4000 the fuel does not follow the boost, you need to pick the position that supplies enough fuel at WOT. A wide band 02 sensor is optimum for tuning. When you raise the boost, the fuel will lean out as mentioned, keep that in mind. It is advised to set the boost and start rich on the position. Then, come back on the position until the desired fuel air ratio is achieved. Keep in mind that the motor initially is in spool fuel mode and doesn't go "on the thumbwheel" until after the first time to 5000-5200 rpm or so, depending on the version.

• When installing the device, always unhook the orange wire behind the battery. When resetting the device, unhook the orange wire for 10 seconds, then reconnect it to insure that it does reset properly. Make sure you always boot up on pos 0 first time after you apply power to the computer. Never move the thumbwheel position with key on, if on position 8 or below. Program could crash. Later versions, V11.82 and later, no longer need to be booted on pos 0.

• First time start up, service engine light, (on solid). Usually, you need to go back under the hood and hook up the MAF (if you use one) and/or the air temp sensor.

• Fast flashing service engine light, key on. Turn the key off, unhook the orange wire by the battery, unplug unit from computer, and use a pencil eraser on the pins underneath, then reinstall. Observe the wiring and check for a pin bent over. Re-boot on position 0. Any position on V11.82 or higher.

• Car runs extremely rich. Check MAF if you use one, and make sure the screens are removed. Check the fuel pressure. Re-boot on position 0. Any position with V11.82 or higher.

• Idle fluctuates up and down. Go to tuning tips section TPS/IAC and set up throttle plate and TPS. Also, check Idle fuel, it may be too lean.

• Can't get enough fuel at WOT on the richest setting. If you are sure the injectors are large enough for the application, check fuel pressure at WOT in 3rd gear and make sure it rises 1 pound for every pound of boost, or close. If the fuel pressure does not follow boost, check or change fuel filter, and check the fuel pump.

• Car stumbles when put into gear. Try adding some DRIVE idle fuel. Check IAC/TPS.

• Car stalls after started when cold. Add Cold Start fuel.

• Scan tool functions incorrectly. Scanmaster logic will cause several functions to read incorrectly on Turbolink, and other standard scan tools. Later chip versions use standard scantool logic so this should not be a problem.

• Direct Scan causes the car to malfunction. Remove the cable and clean off the connector, then reinstall connector, and pull it back a little from being fully seated on the board. Always use a short, shielded cable from the ECM to the Direct Scan box. These are available by emailing Kent at chueng@chuengineering.com. Plug wire radiation under high load is a problem with an unshielded cable. Bad things can happen for what appears to be "no good reason"

• Values won't move in programming mode. Check P/N switch, might still be showing in P or N when in gear.

• Programmed values will go up, but with air on they wont go down. Must be low pressure on air conditioning. Unplug compressor and then go to passenger side, under hood pressure switch on AC tank, unplug it and put a jumper wire across the 2 wires.

• Car will not start, no service engine light when key is turned on. Hook up the orange power wire by battery.

• Car won't start, service engine light does come on with the key on. Take it off TW position #0; the no start setting.