everyone talks about duty cycles and a 11.4 or something a/f what does that all mean? haha noob question big time but yeah i never understood it and thats why i will never get hp tuners to tune my car because ill be lost

 

Air fuel ratio is the ratio of air per unit of fuel thats injected into the intake manifold. Under normal conditions your car runs at a stoichiometric mixture of 14.7 parts air to 1 part fuel. This is best for fuel economy and emissions.

Injector duty cycle is the capacity of the fuel injector at a given rpm. Injectors are pulsed with electrical energy to command them open to spray fuel. The maximum time they can be commanded open is two rotations of the crankshaft before they are spraying fuel for the next combustion event. As rpm climbs, the available time shortens so the injector must be capable of spraying a large volume if needed in a short amount of time. Injector pulse width is measured in milliseconds (ms) and duty cycle is measured as a percentage. The maximum percentage you want to plan on when building an engine is 80%. At 90% or above your injector is not completely closed before the next 4 stroke cycle begins. At 100% the injector does not close and is prone to failure.

 

Damn that's a good explaination.

 

That is why we like having him in pittsburgh...well both him and dan

 

thanks!! so now i know wat to look for when i get a wideband and tune

 

When you're at part throttle, you'll see A/F range from 14-16 all the time as the PCM is constantly making adjustments to search for the best fuel mixture to achieve a stoich ratio.

At WOT on an N/A car usually 12.5-13/1 A/F (lean best torque) is optimum for best power and on a boosted one 11.5-12.3( (rich best torque) is what I tune for. However these cars are overheating internally so its best to tune for around an 11-11.5 until the problem is solved especially if you are creating high horsepower on stock internals.

As reference if you start reading up on tuning forums, when you go wide open throttle and a/f goes towards a richer burn, this is called PE or Power Enrichment. It causes a slight increase in power but most importantly, it chemically cools the combustion chamber.

 

im getting my wideband installed this weekend how does it have to be installed in my dp. i got the AEM wideband.

anybody ?