Chris_T

I tried searching and even tho there are tons of threads on bouncing idles and idle problems with the PFC computer, none talk about actually setting the idle (or whatever it's called). I'm lost as to the function of the computer; it was in the car when I bought her.

My FD's had the computer for over 2K miles now, and it just refuses to learn the idle. Of course, I'm at over a mile above sea level and Calgary's weather changes hourly (no joke, we'll get all 4 seasons in one day), so the computer never gets the same driving conditions twice and I think it's just having a tough time 'learning'.

I've all but got on hands and knees to have my mechanic just set the idle but he refuses, and keeps pushing me to let the computer 'learn' the idle. But it just won't.

I can get over the embarrassing factor of having the idle bounce at red lights like I'm a lunatic ricer trying to race every motor-driven machine on the block. Problem comes when the computer kinda clues in and TRYS to keep a constant idle - the idle is usually some ungodly low number like 100 RPM (no, that's 100, not 1000 rpm) and she damn near stalls (or idles not unlike a Harley Davidson is parked in my back seat, which I don't think can be good for the engine - it sounds like it's choking). So I give her a little gas and the vicious cycle starts all over again. Bounce-bounce-choke-choke-gas-bounce-bounce-choke-choke-gas.

Sooooo, long story short. I want to program the idle manually and forget this whole 'learning' thing, because it's just not working. Are there any ill effects to the engine or the rest of the mappings if I just abandon the idle map and make my own??

arghx

iTrader: (3)

I have made a TON of posts on this issue. Use the search feature to find threads that I have started (there are two big ones) and threads that I have responded to. I have posted many diagrams from the Power FC manual and the factory service manual.

If your ISC valve is still installed (and it sounds like it is), here is the basic process for addressing this issue on most cars with no outstanding mechanical issues:

1. tighten the air adjusting screw beneath the TB elbow to 1/4 turn from closed

2. loosen the dashpot on the TB so the white part does not contact the throttle linkage. This is to reduce the chance of the idle sticking high on deceleration, and is not necessary on every car.

3. check the TPS and adjust if necessary

4. perform the idle learning procedure again

5. drive the car. If it stumbles/surges on deceleration, raise all three fuel cut idle speeds ("F/C AE" , "F/C E/L", "F/C A/C") under the settings-->Rev/idle menu in the Commander. If it sticks on deceleration, lower all three fuel cut idle speeds. You may need to make these adjustments in small increments, as low as 10 or 20 rpm. This part is all trial and error and requires patience. After much experimentation I have had success setting all three settings to 1280 on one car and 1420 on another. But don't just put those values in there and expect them to work out of the box. Those are some baseline numbers to start from.

optional: if you have a wideband, verify that the AFR does not go much leaner than 13:1 at idle.

If you follow this process the idle speed should be right near your base target speed with no fan or A/C on, then should bump up some when those loads are applied. On deceleration the idle speed should be steady and may be slightly higher than your base speed (maybe 1100 rpm) until the vehicle is practically stopped, at which point it will drop.

arghx

iTrader: (3)

also, you need to make sure O2 feedback is off under etc.--> function select in the commander. This will turn back on when you reset the PFC in order to perform the idle learn, so you will have to disable it again.

Chris_T

Ahh, now this is one I never paid too much attention to. My old FC had the deceleration 'stumble', so I've always thought that was 'normal' behavior for a rotary - but mine IS pretty pronounced, even at very slight decels. I'll check that out. THX for your patience.

Perhaps I'm just not using the search correctly, but the only idle threads I could find were all about vacuum leaks and other symptoms I don't have. Would you mind posting the links to those threads?

THX

arghx

iTrader: (3)

baseline throttlebody setup: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/how-make-your-untuned-pfc-basemap-safer-idle-better-no-datalogit-needed-841706/

further idle adjustment discussion: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/new-pfc-idle-sticking-problem-solving-strategy-isc-installed-853278/

arghx

iTrader: (3)

I want to make it clear in this thread as well that the dashpot does not need to be fully loosened 100% on every car. Although it reduces the chance of the idle sticking high, it can sometimes lead to stalling (despite messing with the fuel cut settings) depending on what clutch and flywheel you are running etc.

You may just have to back the dashpot off some to solve an idle sticking problem.