Sutkale Posted May 20, 2012 Report Share Posted May 20, 2012 Okay, where to start with: It's time to fire a Volvo V40 with a following mods (a rough list) - Vipec V88 - Volvo B4204T3 engine block, with Darton sleeves, 84mm bore; 1998cc total displacement - JE pistons and total seal 1st capless rings, 10.2 CR - Cams: 294 degrees at intake (measured @ 1,27mm valve lift), 12.55mm lift, 284 degrees at intake, 11,8 mm lift. Intake valve open 4.2mm @ TDC and exhaust valve 4.0mm @ TDC. - Holset HX50 MFS, (67mm compressor wing, 72 mm exhaust wing, #19 exhaust housing) - 4x1200cc Bosch EV14 + 4X1000cc Bosch EV14 - 2xBosch "044" fuel pumps - E85 fuel - IGN1A (aka "034 motorsport") coil per plug Car will mainly be used in one mile events and occasionally in 1/4 mile events. As you can notice there is really lappy cams in use and practically only minimal vacuum at idle. I am just in the heat of choosing the tuning method and while browsing through the forum, I saw this topic: viewtopic.php?f=3&t=310&start=15&hilit=AFR+correction This open loop tuning method would perhaps suit my needs. However I'm interested to know that how in heck the ECU can calculate the need fuel under different load as the AFR table is the look up table? If I tune the engine to 14.7 at 100 kpa load, (fuel table number 22 at AFR 14.7 and then set flat over the entire fuel table) and AFR table is set to 11.8 at 300kpa, the ECU is able to calculate the needed injector opening to deliver the needed fuel to achiece desired AFR at 300kpa without feedback from WB? Quote Link to comment Share on other sites More sharing options...
Dave Kriedeman Posted May 20, 2012 Report Share Posted May 20, 2012 The engine needs to be tuned using a Wide Band initially. When tuning is complete, if you decide you wish to run a different A/F ratio at a given RPM/LOAD point, then you change the Target Air Fuel table to the new desired A/F Ratio. Back ground mathmatics adjusts the values automatically to change the fuel table to match the new Target A/F Ratio. You do not need a WB A/F meter to be connected to achieve this as long as the engine was tuned correctly with a WB initially. Does your engine run a single throttle body or multiple throttle bodies. If you have multiple throttle setup you need to use TPS as your load axis, however i have used a vacuum balance plenum on multi throttle engines and used MAP as my axis. I have tuned engines using MAP with very low vacuum readings without issues. If you find using MAP or MGP as your load axis gives you issues, then use TPS as your load axis and MAP or MGP as your load axis on your Target A/F table. Quote Link to comment Share on other sites More sharing options...
Sutkale Posted May 21, 2012 Author Report Share Posted May 21, 2012 The engine needs to be tuned using a Wide Band initially. When tuning is complete, if you decide you wish to run a different A/F ratio at a given RPM/LOAD point, then you change the Target Air Fuel table to the new desired A/F Ratio. Back ground mathmatics adjusts the values automatically to change the fuel table to match the new Target A/F Ratio. You do not need a WB A/F meter to be connected to achieve this as long as the engine was tuned correctly with a WB initially. Does your engine run a single throttle body or multiple throttle bodies. If you have multiple throttle setup you need to use TPS as your load axis, however i have used a vacuum balance plenum on multi throttle engines and used MAP as my axis. I have tuned engines using MAP with very low vacuum readings without issues. If you find using MAP or MGP as your load axis gives you issues, then use TPS as your load axis and MAP or MGP as your load axis on your Target A/F table. Okay, thanks! Just got an impression from Ray's explanation that while using open loop -method, just tune the engine to 14.7 AFR at 100 kpa load, the math would do the rest and the ECU would then use the AFR table to calculate the sufficient opening for the injector. The reason I put up this thread, was that different size of turbos pumps air into the engine with various amounts, meaning that one would pump 60 lbs / min and other 80 lbs / min at 300 kpa level, how would the ECU determine the required fuel just out of the MAP which could be the same using different turbos but the amount of air entering into the engine would differ greatly between different turbos used in the same engine, but giving equal load and airflow at 100 kpa where the 14.7 AFR was tuned as starting point for the calculation. Quote Link to comment Share on other sites More sharing options...
lekonna Posted May 21, 2012 Report Share Posted May 21, 2012 Okay, thanks! Just got an impression from Ray's explanation that while using open loop -method, just tune the engine to 14.7 AFR at 100 kpa load, the math would do the rest and the ECU would then use the AFR table to calculate the sufficient opening for the injector. The reason I put up this thread, was that different size of turbos pumps air into the engine with various amounts, meaning that one would pump 60 lbs / min and other 80 lbs / min at 300 kpa level, how would the ECU determine the required fuel just out of the MAP which could be the same using different turbos but the amount of air entering into the engine would differ greatly between different turbos used in the same engine, but giving equal load and airflow at 100 kpa where the 14.7 AFR was tuned as starting point for the calculation. OT: question, are you by any change from finland? i would have send PM but its not enabled in the forums. Quote Link to comment Share on other sites More sharing options...
Sutkale Posted May 21, 2012 Author Report Share Posted May 21, 2012 OT: question, are you by any change from finland? i would have send PM but its not enabled in the forums. Yes I am.. Quote Link to comment Share on other sites More sharing options...
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