RB25 Hunting with PFC?

[Rb.250sx]

Hi, I'm having some difficulties with hunting after installing my PowerFC. I've done the 10 min idle, 10 min AC (I dont have AC, so I just blasted my heater up), and 10 min defroster. Now the rpm idles just fine when start-up...but after a few mins of driving it or idling it, the rpm jumps from like 1000rpm to 1500rpm then back to 1000rpm and back up to 1500rpm continuously, but the strange part is after roughly 30-40mins of driving, the car seems to idle fine for a while with no hunting, but sometimes it continues to hunt afterwards. I'm not sure what's wrong and I'm not too familiar with the PFC. Before I installed the PFC, I turned off the boost controller function (I have an AVC-R), and changed my airflow to Power Intake.

My mods are:

S1 RB25DET Stock Turbo set at 11 psiFMICNismo AFPR - 43 psi w/ vac offGreddy Intake Manifold w/ Q45 TB (fast idle taken off)Walbro fuel pumpKoyo rad with dual fansAVC-R Boost ControllerPOD Filter3" Downpipe and 3" Exhaust throughout

I'm hoping the hunting is something simple and hopefully tuning will fix it, but I'm nervous about spending the cash on tuning and it still hunts like it does now. Please any input is greatly appreciated on what I should look for, or what I should do. Thank you

[captainclutchkick]

you need to leave your airflow set to standard r33 unless you are using a z32 or q45 mass air flow meter

[Rb.250sx]

Thanks, yeah I got the standard RB25 Maf. I'll try to set it to standard and see how it goes.

[gawdzilla]

that might not fix it. the curve values for the MAFs at that low voltage is basically identical for all the MAFs, so it probably wouldnt affect your idle. Try messing with the idle screw some and make sure its not too far out or too far in.

[Darius]

Did you set your base timing to 15-degrees?

By removing the fast-idle on the Q45 TB you mean you took off the spring right?

[Rb.250sx]

Did you set your base timing to 15-degrees?

By removing the fast-idle on the Q45 TB you mean you took off the spring right?

Yes by removing the fast idle, I took off the spring. Again, I'm not too familiar with PFC, I've just installed my PFC again and haven't taken it out for a spin yet since I got to bleed my brakes first. Hopefully it drives fine, if not how would I go about setting the base timing to 15-degrees or check if it's currently at 15-degrees?

p.s gawdzilla, I've set my idle to around 850rpm by adjusting the idle screw on the intake manifold. Is that okay?

[Darius]

You really need to set the base timing before setting up the PFC because that is what it uses to advance/retard timing from. Changing your timing changes your idle speed so I would get a timing light on it and do that first. Check out the FSM for engine timing procedure. Then if you still need to adjust the idle, make adjustments then.

[gawdzilla]

850 should be ok... is your screw somewhere in the middle of the adjustment? if its really far out or all the way in, something is wrong.

is your TPS sensor at .5v when throttle is closed? (check that on the pfc)

if you have PFC you can set the timing by making the timing gun match whatever the PFC is displaying as the timing. i.e. if the pfc is saying your current timing is 15 degrees, the gun should show 15 degrees too.

[Rb.250sx]

850 should be ok... is your screw somewhere in the middle of the adjustment? if its really far out or all the way in, something is wrong.

is your TPS sensor at .5v when throttle is closed? (check that on the pfc)

if you have PFC you can set the timing by making the timing gun match whatever the PFC is displaying as the timing. i.e. if the pfc is saying your current timing is 15 degrees, the gun should show 15 degrees too.

Yeah I believe the screw is somewhere in the middle. Where do I navigate to get to the screen where it shows my TPS sensor volt and also the current timing (I have a commander btw)? I just drove it around and it seems to be driving okay, there's no noticeable hunting and idles just fine and drives smooth. I'll probably try to find out the voltage of the TPS and the timing tomorrow morning if I don't get a reponse here on how to look for it, thanks gawdzilla and Darius for your reponses, I really appreciate it

[gawdzilla]

Yeah I believe the screw is somewhere in the middle. Where do I navigate to get to the screen where it shows my TPS sensor volt and also the current timing (I have a commander btw)? I just drove it around and it seems to be driving okay, there's no noticeable hunting and idles just fine and drives smooth. I'll probably try to find out the voltage of the TPS and the timing tomorrow morning if I don't get a reponse here on how to look for it, thanks gawdzilla and Darius for your reponses, I really appreciate it

From the main screen, go to Etc. , then go to the one titled "sensor/sw check" or something. one of those is your TPS voltage

[URAS]

yeah do your base timing first if it still hunts go into the idle control screen and move the FC/1 and FC/2 rpm settings closer to your idle rpm. if you get stuck email me [email protected] i tune around 10 or so PFC's a week. http://www.fc-datalogit.co.nz is a great investment if you want to unlock all the features of your fc. I could not live without it, the hand controller is **** for tuning and does not allow you to access half of the FC's features.