Agree.Holden202 wrote:well actually that is roughly a 25% change and yes that is pretty major, if your needing to change that much then you really should be leaving the idle AFR tables alone and adjusting the VE table!
The ecu works like this: its measuring air pressure, and using the ve table to know at that pressure and rpm how much air is ending up in the cylinder. Then it takes in to account temperature, and looks at the AFR table, and works out how much fuel to add (simplified, but more or less thats the process). So the ecu gets its target AFR from the conditions and the AFR table, and injects the fuel. If everything is right the actual AFR should be the same as the target AFR. What your doing is moving the target AFR to drag the actual AFR to where you want it. However this throwing out the temperature corrections etc. You should be leaving the AFR tables and modifying the VE table, and in tuner pro look at the monitors page and chart target and actual AFR over the top of each other.. and when you get the VE table right the actual AFR will stay pretty close to the target AFR. Thats when your tune is good.
You might want to edit the adx a little too, and change the working for target and actual AFR to put the words target AFR and actual AFR on the sides of the monitors, as without it you'll just have two values named AFR.
Remember that when your accellerating you'll get the enrichment or decell enleanment, so actual AFR is allowed to swing further from the target AFR under those conditions.
Also do this with a warm engine so that your warmup compensation stuff is taken out of the picture while you get the VE right.
update: actual AFR is wideband AFR.