Toyota VAFM adjustment and calibration

cre · 09-02-2011, 12:22 AM

If you're running a 7M-GE you're most likely still running the stock VAFM (and it's probably been dicked with at some point or another). I'm not one to recommend tinkering with it... there's not really any power to be freed up in the 7M-GE by screwing with the idle mixture and dicking with the vane isn't a good idea unless you've got a wideband and can log what the changes are doing, but here's the info anyway.. I'll start with how to restore the mixture screw:

There's a small cylindrical tower on the side of the VAFM toward the back where it connects to the intake piping. There's a metal cap which is pressed into place to protect the screw. If the cap hasn't been drilled out then it hasn't been tampered with and unless you find reason to adjust it you may leave it alone and rest assured it's still in the factory position. If the cap is gone then check the following:

At the base of the cylindrical housing you'll find a two digit number stamped into the metal. Take this number and add 100 and then divide by 10. So if it is 25 you'll get (25+100)/10 = 12.5 This is the number of millimeters the head of the screw should be from the outer lip of the housing/cylinder.

Adjusting this screw adjusts how much unmetered air enters the engine at any given point. Naturally, when running in closed loop (not at idle and not at WOT or while the engine is still cold) the ECU will adjust fueling to maintain a stoichiometric mixture. This screw WILL affect your AFR at WOT, idle and when the engine is cold... so tinker carefully or you may end up damaging things.

Below are some links to more information and possible tweaks for the VAFM. As with any mod (or hack as I consider these) use care.

http://mr2oc.com/showthread.php?t=287627
http://mr2wiki.com/MKII/3vzfetune
http://www.mr2oc.co.uk/forums/mk2/h...4.html?start=14

On last note is that the folks who've posted this information in other forums are almost always running turbo or supercharged engines... With a N/A it's very likely that you will see little to no real gain (just what you imagine).

09-02-2011, 12:22 AM	#1
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Toyota VAFM adjustment and calibration If you're running a 7M-GE you're most likely still running the stock VAFM (and it's probably been dicked with at some point or another). I'm not one to recommend tinkering with it... there's not really any power to be freed up in the 7M-GE by screwing with the idle mixture and dicking with the vane isn't a good idea unless you've got a wideband and can log what the changes are doing, but here's the info anyway.. I'll start with how to restore the mixture screw: There's a small cylindrical tower on the side of the VAFM toward the back where it connects to the intake piping. There's a metal cap which is pressed into place to protect the screw. If the cap hasn't been drilled out then it hasn't been tampered with and unless you find reason to adjust it you may leave it alone and rest assured it's still in the factory position. If the cap is gone then check the following: At the base of the cylindrical housing you'll find a two digit number stamped into the metal. Take this number and add 100 and then divide by 10. So if it is 25 you'll get (25+100)/10 = 12.5 This is the number of millimeters the head of the screw should be from the outer lip of the housing/cylinder. Adjusting this screw adjusts how much unmetered air enters the engine at any given point. Naturally, when running in closed loop (not at idle and not at WOT or while the engine is still cold) the ECU will adjust fueling to maintain a stoichiometric mixture. This screw WILL affect your AFR at WOT, idle and when the engine is cold... so tinker carefully or you may end up damaging things. Below are some links to more information and possible tweaks for the VAFM. As with any mod (or hack as I consider these) use care. http://mr2oc.com/showthread.php?t=287627 http://mr2wiki.com/MKII/3vzfetune http://www.mr2oc.co.uk/forums/mk2/h...4.html?start=14 On last note is that the folks who've posted this information in other forums are almost always running turbo or supercharged engines... With a N/A it's very likely that you will see little to no real gain (just what you imagine). __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->