Pfc Tuning Question

[fletch63]

Hi all,

I have just bought an R33 GTR (upgrade from my R33 GTST) and in the process of ironing all the bugs out.

Wondering if anyone who knows PFC's could help as I've never had 1 before.

The idle is high and a bit rough. (1100-1200 RPM)

I adjusted under the bonnet and it goes all the way to the end of adjustment and is still too high.

When I try to turn down on the PFC it hunts like crazy.

So I had a look at the ign timing on the PFC and it says 0 degrees

Thinking this was odd (my GTST was set at the CAS for -20 degrees) I changed the ign timing on the PFC to - 15 degrees and the idle went right down to 800 and was beautiful and smooth.

But when I accelerated no power at all.

With my limited knowledge of tuning I suspect that the fuelling maps would now be - 15 degrees out so that explains why it was sp sluggish.

So if this is correct should the ign timing and the maps be changed or should this really be at 0 degrees and something else is wrong.??

(it goes great at WOT by the way)

Also can anyone recommend a good tuner with a 4WD dyno that will do a good job??

Thanks guys

[Hanaldo]

I'd say you're on the right track, but it's not the fueling maps that are out it's the ignition maps. By changing the base timing from 0 to -15 degrees, you've taken 15 degrees of timing out of your whole map. So it would be terrible down low, but still ok up top.

Best thing to do would be to get the tune checked, it could be something completely different that we don't know about.

[t_revz]

I wouldn't be advancing the timing 15 degrees and giving it a hard time. Who knows how it was set up.

Check timing with a timing light or take it somewhere.

[fletch63]

Thanks guys,

Any suggestions for a good tuner

Allstar Garage????

[NISMOGTT]

Thanks guys,

Any suggestions for a good tuner

Allstar Garage????

i have used allstar for quite a number of years without issue

[fletch63]

I was tossing up between Allstar and Tokyo Motorsport in Welshpool

After speaking to both on the phone I have decided to book in with Tokyo

Anyone had any dealings with them??

[t_revz]

What was your reason for choosing them out of curiosity?

Closer to home? Cheaper?

[fletch63]

What was your reason for choosing them out of curiosity?

Closer to home? Cheaper?

Not many tuners have 4WD dynos and these 2 have been recommended once each (not sure about them though)

[xRacerx972]

I apologize if you already knew this, but..

The PFC must learn the idle of the car once you first install the unit.

What I did was initialize the PFC, configure the injector correction (for bigger injectors), then follow the idle learn process that can be found on the paulr33 site.. if you dont have the boost control kit,make sure thats turned off in the etc menu.

Also, it helps to verify your aac valve is clean and operational.

I would advise against changing the timing to accomodate the idle as said before, youre making temporary changes to the entire map.

After my self-learn process, my car idled at a solid 700rpm. A little low, but fine tuned with the adjustment screw from there, which is also a process, not simply turning the screw.

Keep in mind, if theres already a tune saved to the unit, you will lose all of that data by initializing the unit. It will take you back to the japanese base map for a completely stock setup.

[GTRNUR]

The correct idle speed for an RB26 is 900 RPM with an ignition advance of 20 degrees. The PFC locks this ignition timing at idle, so the base map ignition values are not even used.

Correct procedure to set idle would be:

1.Set your ignition timing to 20 degrees at idle by using a timing light at 900 rpm. (You may need to do this multiple times during the process if your idle speed is high, as the ecu will use MAP values instead of idle lock values.)

2. With the car warmed up, adjust the air bleed under the throttle plenum so that the flat top adjustment screw is flat with the top of its casting. (starting point)

3. Loosen the lock nut on the throttle stop. Start the car and wind the throttle stop counter clockwise to close the throttles and reduce the idle speed.

4. If you achieve close to 900 RPM using this method then great but it doesn't have to be perfect. A little higher than 900 is ok. If your throttle stop screw is no longer stopping the throttle, then you have either a vacuum leak, or someone has cleaned the throttle seal spray off your throttle valves.

5. So its idling at 925-950 RPM now. Lock the throttle stop nut.

6. Loosen the two bolts that hold the TPS sensor on the throttle assembly. Adjust the position of the sensor so that you are seeing 0.45 volts on the TPS Signal. Use the commander or FC Edit to read these values from the ECU. Then tighten them up again.

7. Re-check your 20 degrees ignition with the timing light, and adjust the idle speed air bleed under the plenum to achieve 900 RPM.

This is a hot idle speed adjustment. With this done, the ECU then needs to have its Idle speed AUTO Learn procedure done so that it can correctly control the PWM air bleed valve to allow the engine to fast idle when cold, and to correctly control the air speed under electrical loads and air conditioning loads.

This is also the basic method to get things close. If your engine is idling so badly, you may also need to adjust the base fuel map settings while reducing the idle speed. You can get it very close by ear if you don't have a wideband AFR meter.

Aim for 14.2-14.7:1 if you have a wideband meter. Otherwise, if the engine begins to falter, add fuel at a small rate for the idle cells until it stabilises. Once the idle speed is stable (but not perfect, step 6 above), you can slowly remove fuel from the idle cells until you hear/see a drop in engine RPM. This is the engine going from stoich to lean. Add a tiny bit more fuel to stabilise again, and this is your sweet spot.

[Hank Scorpio]

Holy thread dig batman!