[longassname]

yes the ecu cuts fuel during engine braking. If the engine is not coupled to the wheels it needs fuel and spark to maintain idle.

If you get very poor around town fuel economy it is because of the condition of your car. The ecu with the oe programming uses the knock sensors to add in ignition advance. If your compression is low and or your knock sensors aren't good you end up driving around with less than optimal ignition advance and less than optimal power and fuel economy. Bad temp sensors also cause poor fuel economy--so do bad oxygen sensors--so does an inoperative egr.

Check your sensors and check your compression. Replace any bad sensors and if your compression is low put in hotter ngk plugs with platinum chips on the ground strap, pfr5b-11 or ifr5e-11. Keep your eyes open on the feedback on the new ECUtune Stage1Av1 software; you might want to consider getting it in addition to the above.