Hi, I just got my pfc and my idle is no good. I went through the whole 30min thing where I let my car warm up from dead cold, let it sit, turned on the parking lights, then turned on the a/c, and then drove the car around. I also cut the 4 wires that everyone talks about as well. Its been two days now and my idle is still be jumping around. It revs between 1K-1.4K a few times and slowly drops down to around 800.

If it matters I have the newist edition straight for the Japanese market but I doubt that is an issue.

Anyone got any ideas?

 

isn't it supposed to drop to 1500 or so and then ease down to regular idle? what are your idle settings set to?

 

Base settings, I havent changed anything.

The start up and warm up is fine, revs up to 1.5K till the engine is warm then idles fine. Only when I start driving and let off the gas does it do this reving stuff. Like at a stop light and such.

 

It sounds like you are having the exact same problems I was when I installed mine. It would idle perfect after starting, but as soon as you hit the gas and let off, it starts to idle surge. The best thing to do that makes the biggest difference is to unplug the idle speed control plug under the UIM, it is inbetween the UIM and the firewall, it is the only white plug. You can see it and unplug it without removing anything, it's alittle tricky to unplug the first time you do it. After you do that your idle bouncing/serging should stop like mine did. Then you may need to make other idle adjustments on the TB, like the one on the TB under the elbow, it is a flat head screw, I only had to adjust that one, I think I had to do it to raise or lower the idle, sorry don't remember exactly. I spent many hours doing all the idle learning process many times which would not help, so save your gas money and stop trying that.

Unplug the white plug/wire connector now! Don't worry about it being unplugged. Then test it out, I think it should be better. Then go into the PFC RPM (idle) settings, and raise all 3 of the "F/C" settings to above 1200 or 1300 rpms, then you should not idle surge after letting off the gas when driving. I did all of the above and it works great. After you do all this let me know if it is all good, and there is more to do because the car is alittle hard to start when hot, then you may have to adjust the "Cranking Fuel Injection" settings like I had to do to help the hot starts.

Hope this helps, let me know how it's going.

 

it also helps to take fuel out of the "Inj Map" Fuel Correction Map cells where you idle at, go to the map tracing mode in the monitor section to see what map cells you idle in. It helped my car to lower the numbers in the first two columns and the first 8 rows, this helped my hot starts the most and I am pretty sure the exhaust does not smell as rich during idle. I made all of them the same number which helps to smoothen out the idle, they are 110. Don't touch anything else on the maps. I did this before adjusting the "Cranking Fuel Injection" settings.

The idle settings are in the "Rev/Idle" settings menu.

 

The PFC idle problem has been around since the world was created! There are probably more post about it than any other subject.

A search does help.

As always, help the PFC with a manual reduction of the idle speed until the speed is within the range controlable by the PFC.

Or using a DATALOGIT, disable the ISC and set the idle at 900 with A/C and full electric load.

 

Chuck baby, finally coming around to acknowledge that the best idle control is no ISC and simply adjusting idle with the manual idle bleed screw and TB settings!

Well, at least when the PFC stops controlling idle which it often does with a radical engine/turbo setup.

 

Thanks for all the info guys. Im gonna try to unplug the isc and adj the idle air/tb settings today.

Wish I had a datalogit... lol

 

You can not do it 100% without the datalogit.

Without the DL you put the three idle speeds down to 500, disconnect the ISC connector, and may also have to turn of O2 idle control.

With the DL, you set the three speeds to 0.

 

From my experiences, It doesn't help or make any difference for the most part if I turn off the O2 F/B control or the turn off the idle-IG Cntrl in the "Function Select" menu (after etc. menu), with the ISC unplugged.

 

Sometimes they do interfer since both affect the idle.

With the rpms set to 0 with the datalogic, it disables Mazda's idle timing control and allows you to tune the IGL/IGT for best idle. Idle quality can thus be improved.

 

Dont know what its called, but a member let me know that i coould disconnet it, its the lil white connector under the UIM, I was told it was for idle, and also just to be on the safe, check and see if you main cat is clogged, dont know hope this helps. GOD BLESS !

 

You are talking about what I was talking about in my first post in this thread, it is the idle speed control ISC white plug/wire connector. It needs unplugged to get rid of the idle surging after hitting the gas, the car will idle good after you start it, but not good after hitting the gas if the white plug is connected.

 

Chuck,

How does timing affect the idle? My timing for IGNL for P04&P05 - N02&N03 looks like:

8 8
8 17

and IGNT is:

8 8
0 17

Im not sure what to change and why. any help would be appreciated.

Thanks.

 

OK, so with a datalogit, what all is required. Unplug the ISC? Uncheck idle/ig control? Set all of the idle speeds to zero? All of the above?

 

If you observe your actual idle timing with the commander, it does not match what is in the IGL/IGT cells. If you totally 100% defeat the idle control as I said, the PFC will run what is in the idle cells.

 

I originally had idle control OFF. I recently turned ignition control OFF. Before, I would see the timing jumping all over the place at idle. Now it is more stable. However, I see 10-11 for both leading and trailing timing on the commander with the timing set as above. It would seem to me that the ecu is averaging the 8 and 17 numbers to come up with 10 - 11. Of course that is just a guess on my part. I have two questions for you.

1. Does timing affect A/F ratio at idle (or anytime for that matter)?

2. Is it safe to mess with the timing in the idle cells to find the best idle quality?

Thank you very much for your help so far.

 

(1) Minor timing changes has no affect on AFR, large changes will have a little at most. These changes have more affect on EGTs, as any fuel not burned in the rotor chambers will burn in the exhaust system.

(2) Do not be paranoid!