EdwardNorth

Hey all,

The learning process seems to be going very well for my FD with the PFC, but there is one thing I'm curious about. When I accelerate lightly or am just maintaining a normal speed while cruising down the road, the car seems to be pulsating just a tiny bit. My wife didn't pick up on it from the passenger seat even after I said something, it's that light. But it feels like the car is ever so slightly pulling a tad harder, then slowing a tad, pulling a tad, slowing a tad. If I get near or into boost while accelerating it completely vanishes, but if I'm more than 5 or so inches of vaccuum while accelerating, it happens. Not a big annoyance but it doesn't feel right.

Looking at the a/f gauge shows a pulse from lean to rich and back again every couple of seconds. Reading the injector duty monitor on the Commander shows a continuous 5 or so percent change in duty (i.e. it fluctuates between say 13 and 17 or 18% in unison with the a/f gauge indications).

Could it be that the PFC is still learning how to control the car in cruise conditions? Or do I need to change a setting somewhere? I haven't had as much time to read the manual as I would like to have, and I haven't driven it since Sunday (PFC installed on Saturday) , but I want to find out what to try before my next "session".

Thanks guys.

RotorJoe

Look to the threads about the 02 sensor feedback. Try playing with that. Turn it off and on and feel for the differences. I have heard of people turning it off and adjusting the fuel in the cells that are effected when the surging happens. I however never had problems with mine and leave the 02 sensor feedback on. With it on you will see (under no load/boost conditions) your air/fuel meter go from rich to lean pretty quickly.

Anybody else have a take on this?

EdwardNorth

That did the trick! I turned it off and the car is smooth as silk now at cruise and very light acceleration. The A/F gauge is now calm, but still shoots up to green when stepping on it.

Thank you very much for the tip!