Since I have installed my PFC, my FD has had a slightly noticeable repetitious surge around 2100 RPM. I just got the commander so hopefully,with your help, I can tune it out. Any advice will be appreciated.
Thanks
Rick

 

I think this was brought up a while ago.. Does it happen when you're "just on" the throttle? It's the lean-cruise mode for the power-fc.. it uses the o2 sensor to try to lean you out to keep mileage up.. you can turn off the o2 sensor with the commander, and have it just run off of the maps..

 

Hmmm.. Im experiencing this surging problem as well, but I have noticed that when i removed my air-pump that this problem was reduced... Is it really prudent to stop O2 sensing? Could that cause any problems with leaning out @ any obscure moments like with deceleration or idling?

 

Surging is most noticable in 3rd gear cruising steady around 2100 RPM.
the o2 sensor numbers change several times per second from 1? to 82. WOT the o2 will be a solid 88 to 95.
I am hesitant to turn off the o2 sensor. I am afraid my engine will blow up. Is there another solution? My engine mods are M2 intake, M2 med. IC, Pettit downpipe, Racing Beat cat back and Stock PFC.
Rick

 

Are my o2 readings(above post)close to what others are getting?
Thanks
Rick

 

The lean condition happens to alot of "better than stock" breathing RX-7's.

The fix is easy. Just find the cells that are leaning out and bump a little more fuel into them. Just by taking a quick glance into the fuel map you're running you can probably see a big drop at light load/low rpm in the programmed values.

Shouldn't take you more than a few minutes as you will notice the chance immediately.

Good Luck!

Rob

 

Thanks Rob
That does sound easy. Now if I can only figure out how to do that
I will be set. The PFC manual is vague with its instructions. I am not even sure which page will get me started. Please explain with more detail.
Thanks
Rick

 

Hey Rick and Others,

Under Monitor Mode you'll find the Map Tracer which shows real-time what cell your ECU is pulling from while running.

Drive your car at the point/points your car is suffering the lean condition surging and figure out which cell/cells this occurs while monitoring the Map Tracer.

Now, under The Settings Mode you'll find INJ Map which is your fuel map. Listed are the exact same cells you saw while in the Map Tracer. Go to the cell/cells that you have found to be too lean and edit them. Add a little fuel to each cell until you notice the surging has been eliminated. Your O2 voltages will also stop fluctuating lean-rich-lean after fixed.

Good Luck!

Rob

 

doesn't the o2 voltage often flcutuate at light throttle(cruising) and at low rpm? I thought it was normal. am I to think I am running lean if I see that?

 

The O2 surging we are talking about does happen at light load/rpm. The O2 sensor voltage bounces continuosly between very low-high voltage and will smooth out with increased load or revs.

If you are seeing this kind of cycling than more than likely you are also experiencing a lean condition.

Just run a quick check and add some more fuel into those cells and see if it goes away!

Rob

 

Yeah, what you are seeing (bouncing 02 voltage around) is the light load lean cruise mode.. and yes, it tends to surge a bit, or actually run a little lean (at almost no load, it's not a big deal at all.) And yes, you can bump up the fuel in those cells.. but that's not really the route to take. It'll straighten out the pulsating because the "lean mode" is programmed to only work at very low fuel numbers.. if you crank it up to just above this limit, it'll kick off the lean mode, but you'll be running even richer than you want to. Just turn off the o2 sensor. You're not blowing anything up. You're just running the computer directly off of the maps, instead of having the computer guess at just how much it can lean things out. I've been running with the 02 sensor off for the last 6 months.. no problems. And no pulsating.