new to forum. power issue df 140

[plumber1]

Engineers at suzuki somewhat stumped....... at WOT with every thing else checking out AOK, throttle position sensor only reads 60%.

so 4800 and 28 mph now makes sense, but noone has heard of this............. Any thoughts?

[redlowrey]

If the throttle is getting to the wide open position, the signal voltage at the ecu should be a bit over 4 volts indicating wide open throttle, map sensor signal voltage around 4 volts too. Your engine is equipped with a knock sensor, if for some reason it detects knocking in the combustion chamber it will retard the timing till it stops. Because your engine has a cable and is in the wide open position your computer will reduce the ignition timing and injection pulse width to suit a throttle opening of 60%, if it had electronic throttle control it would have closed the throttle to suit.

I could be wrong, but its new, was running like a jem and nobody touched anything, put away for the cold weather. With a cable throttle, if you retard the timing and don't reduce injection pulse width the engine will start running rich because the map sensor signal voltage will stay higher for longer because of reduced manifold vacuum.

To pluck a figure of 60% the engine has been on an sds and the techs should have been able to see all the parameters. With the engine off key on, wide open throttle, the sds should be able to show you 90 % of throttle opening and the signal voltage to indicate wide open throttle.