power band question

[studabaker]

I have my engine out but I remember there being a distinct difference in the engine sound and power at one point.

Does the computer switch to sequential timing at 2500 rpm possibly or in any other way change anything in the engine management and what factors are monitoredby the ecu to cause this. While taking apart my engine there was a crack in my knock sensor and my sensioner does not seem to be requiring compression to reinstall. The tensioner is not working.

I would guess the relevant sensors are knock sensors and air flow mass sensor and cam position sensor.

It makes sense to me the the pistons might fire in series to generate more torque and then in sequence at higher rpm. The crank suggests they can only fire in series, such as two together.

What am I hearing and feeling in the 420a engine at max power in the power band? It seems to change?

 

[studabaker]

The only thing that would make sense is that the throttle is fully open. I have found this referenced many times on this site. I am interested in this as I am rebuilding the non turbo engine and potentially into a turbo and I am trying to better understand what is going on with the programming of the computer. I am also interested in the factors which case the computer to open the throttle all the way. In order to improve any driver problems with my car.

 

[studabaker]

"The main advantage of a sequential system is that the entire system has a fast response time when the driver makes a quick change. More or less fuel can be released when the next intake valve opens. For systems that do not use sequential fuel injection it will be necessary for the entire engine to complete a revolution before the fuel to air ratio can be altered. This type of injection also produces much lower emissions and provides even better fuel economy. Because the fuel is altered for each cylinder, you can potentially get the best performance out of the engine that is possible. The throttle response is immediate, which allows for very rapid changes in the fuel to air mixture. Because fuel is used more economically, the emissions released are lower. This is very important where vehicles are being produced to meet stricter emissions."

Sequence means in order and series means in combination. In series gives more hp and less response and less fuel economy. I believe that my engine management switched to sequential occasionally and that is what I was feeling and there is not a horsepower benefit to this however fuel flow response would change quicker which may be beneficial to road race course or street driving.