Power FC/Datalogit file/map upload help? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

dj_cally_17 · 03-06-2016, 05:09 PM

Hey guys,

Ive been having idling issues with the power fc. I think it has to do with the initial idle learning procedures. So with that now I have to reinitialize, which wipes off everything. but luckily i have a saved copy of the dyno'd map of the tune. Would it just be as easy to go to file and open to re install the file/map onto the power fc with the datalogit or is there more to it?. TIA

Kingtal0n · 03-06-2016, 09:56 PM

Dont initialize for idle learn. it learns constantly forever. If you have electronics that change idle load (like fans) the idle will never be consistent because it will constantly be learning two different engine loads, or more if you have more electrical load devices.

The A/C compressor has its own idle-up valve, so it isnt as big of a problem when it comes on. But thats the only idle up valve on the engine, the IAC has to open and close and the power FC has a huge problem with that historically, whether because most IAC valves are just old or the programming isn't very good I am not sure, but I've always had to do special things to get idle quality out of a power FC.

heres an example. If I want 850rpm idle speed. I can set the computer to try to hold 850. The problem is, when the fans kick on, the idle speed drops to 700. No good. And the PFC can't learn intermittent electrical load idle speeds. So what I've done is, added airflow at the IAC manually (use a screwdriver) to bring the idle up some (920~rpm) then program that spot on the fuel map very lean, so the engine avoids it (it never reaches 920rpm because that cell has no fuel). This way the idle stays down at 850 or whatever, and when the fans kick on, it stays put, because there is so much extra air coming in the engine doesn't feel the load.

You also need to be careful if there is a maf sensor, it needs an air filter on it, needs straight ends before and after as much as possible, get it as far from the turbo as possible, and you need a bypass valve recirculated away from the maf so the maf doesn't pick up any surging behavior. When using a stock turbo, there is alot of surging behavior near idle speed, you can't really hear it unless you have a stock exhaust. The light surging near idle screws the maf signal up, makes the idle inconsistent. Watch your maf voltage while idling that it sits still, maintains a consistent value. usually it will, until you touch the throttle. Then, the additional flow through the engine excites the turbo, and let off the throttle, the air has no where to go (thus the need for the bypass) and it exits the compressor, stalling the air through the maf, causing the maf voltage to whip around.

03-06-2016, 05:09 PM	#1
dj_cally_17 Join Date: Nov 2013 Location: United States Posts: 17 Trader Rating: (0) Feedback Score: 0 reviews	Power FC/Datalogit file/map upload help? Hey guys, Ive been having idling issues with the power fc. I think it has to do with the initial idle learning procedures. So with that now I have to reinitialize, which wipes off everything. but luckily i have a saved copy of the dyno'd map of the tune. Would it just be as easy to go to file and open to re install the file/map onto the power fc with the datalogit or is there more to it?. TIA

03-06-2016, 09:56 PM	#2
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,828 Trader Rating: (17) Feedback Score: 17 reviews	Dont initialize for idle learn. it learns constantly forever. If you have electronics that change idle load (like fans) the idle will never be consistent because it will constantly be learning two different engine loads, or more if you have more electrical load devices. The A/C compressor has its own idle-up valve, so it isnt as big of a problem when it comes on. But thats the only idle up valve on the engine, the IAC has to open and close and the power FC has a huge problem with that historically, whether because most IAC valves are just old or the programming isn't very good I am not sure, but I've always had to do special things to get idle quality out of a power FC. heres an example. If I want 850rpm idle speed. I can set the computer to try to hold 850. The problem is, when the fans kick on, the idle speed drops to 700. No good. And the PFC can't learn intermittent electrical load idle speeds. So what I've done is, added airflow at the IAC manually (use a screwdriver) to bring the idle up some (920~rpm) then program that spot on the fuel map very lean, so the engine avoids it (it never reaches 920rpm because that cell has no fuel). This way the idle stays down at 850 or whatever, and when the fans kick on, it stays put, because there is so much extra air coming in the engine doesn't feel the load. You also need to be careful if there is a maf sensor, it needs an air filter on it, needs straight ends before and after as much as possible, get it as far from the turbo as possible, and you need a bypass valve recirculated away from the maf so the maf doesn't pick up any surging behavior. When using a stock turbo, there is alot of surging behavior near idle speed, you can't really hear it unless you have a stock exhaust. The light surging near idle screws the maf signal up, makes the idle inconsistent. Watch your maf voltage while idling that it sits still, maintains a consistent value. usually it will, until you touch the throttle. Then, the additional flow through the engine excites the turbo, and let off the throttle, the air has no where to go (thus the need for the bypass) and it exits the compressor, stalling the air through the maf, causing the maf voltage to whip around.