I have a UK spec MY02 with decat up pipe, decat downpipe and a PE sports catalyst with PE remap.

When I’m driving in higher gears around 2500 RPM on light throttle I often get slight hesitation, I’ve tried to log it with DD and all I can see that looks out of the ordinary is the lambda voltage dropping for a fraction of a second from around 0.9 to 0.2v. This seems to happen as I get positive boost.

Could this be caused by the engine developing boost much earlier than normal due to the decat?

What parameters should I log to help diagnose the fault?

On a full throttle run the lambda voltage is between 0.95 and 1v which is what I would expect.

Any advice or suggestions welcomed.

Cheers

Edward.

 

There's not a problem with those readings. It's normal. At light throttle the ECU is in closed loop mode hence the up/down readings. Perfectly normal.

As for the hesitation it's a case of "they all do that sir".

Cheers,

Wrexy.

 

If you want to see you air/fuel ratio, rather than a voltage, log 'Air/Fuel Sensor #1'. This gives you a lambda reading. On cruise, this will be close to 1. On full throttle, this will drop (get richer). Also, on cruise, lambda may not be exactly 1, since the ECU biases the target lambda subtley according to load & RPM.

Cheers

Steve