hey guys...

just spent the evening tuning my car and that notorious pfc that I had tuned by xs. I ditched their wacked settings and maps in favor of the houston 2 maps.... and went from there

Im learning a lot about where I need to put fuel according to my mods...I used chucks maps and then added fuel at 2800 rpms where the boost comes on full from the m2 set...removed some at 3200 rpms since chucks maps are for a non seq car...added more at 4500 rpms since chucks dont have the transition...and kept the high end juice the same....maybe a half point higher in some cases.

my car is running very quick...Im starting to smile when I drive around finally!! Im only boostin twelve lbs (not an efficient boost level for the m2 set which run better from 15-20 lbs) until I get it on the wideband soon.

Ive learned a lot with the help of you all...I still have a couple questions.

when I let off the gas and come to a stop the tach has an unpredictable tendency to drop to about 400 rpms...it will simply stall. I tried adding more fuel at 400 rpms which made no difference...I also turned the idle up to 1000...no difference either. DO ANY OF YOU KNOW WHY THIS IS? If I blip the throttle when its idling below a thousand I can feel a slight hesitation...very slight...but only if I blip the throttle. if I let off the gas hard as I come to a stop it stalls on occasion. this is a new development. why why why?

if a car is running too lean...lets say 12:1 or 13:1 will I hear the motor or feel the motor running poorly? AT WHAT FUEL RATIO WILL I ACTUALLY HEAR AND OR FEEL DETONATION???? (I should ask xs ...their map showed me exactly what detonation feels like) jiffy pop under the hood with jerkyness for flavor!!

the car is finally running quick...I can feel when it runs rich and started that way...it would bog a bit under accelleration...slowly I eased back until the bogging stopped and the car ran quickly and smoothly.

I ran six gallons of 100 octane race gas on a full tank as well as three bottles of octane booster. DOES THOSE BOTTLES OF MOBILE OCTANE BOOSTER DO ANYTHING?

thanks guys..any input is greatly appreciated.

Im going to limp it around til I get it on the wideband but Im wondering what the answers to those questions are.

j

 

another question...

does tuning with race gas hurt me once I get back to running crappy 91 octane?

should I richen it up with the race gas so that when I go to premium I dont blow my seals through my hood?

thanks

j

 

You could try increasing the fuel cut recovery value. This is the RPM at which the injectors start firing again following closed throttle (when they are at 0%).

Alan

 

cool thanks

Ill try that.

why would it just start happening out of nowhere?

anyone else know the answers to the above questions?

thanks!

j

 

Jason, I don't know the answers to all your questions, but my car was doing the 400rpm and then bogging out and dying thing. I checked my sensors, and my h20 temp. thermosensor was bad causing the Power FC to flood at idle. Also I wouldn't tune your car with race gas, or octane booster, unless your going to be running constantly with those. There have also been a few threads about how little those octane boosters work. Good to see your car is running, can't wait to hear what your car will do when it's tuned.

eric

 

thanks eric..I appreciate it

if any of you know the rest of the answers..please share.

j

 

I responded about the octane boosters, in favor of them, or atleast the Prestone brand in the orange bottle. I would consistantly get 45 to 50 as a knock number at WOT in 4th gear, starting using the octane booster, dropped down to 20 to 25 at WOT in 4th gear. Quit for 2 tanks, watched as the knock level rose back to the mid 40s again, started using the prestone again, dropped the knock numbers down again in the 20s. So atleast the Prestone brand DOES increase the octane rating, thereby lowering the knock number. I've since increased the timing a couple of degrees in my car and the knock number went up but still around 35 or 40 at WOT with the octane booster in it.

As far as using high octane race gas. Unless you are going to use one of the boost settings for normal driving, and the other for higher boost/higher octane gas, then don't bother like hapa said. unless you will be using it every tank full, which you won't at $3.00 plus a gallon, its beyond me why people do this. Tune it for race gas, run out of race gas, timing is still high since you tuned it for the race gas, POOF!!!! There goes my engine, and we start hearing "the rotary is to fragile" etc. Stick to tuning it using the octane you have available to you.

Tim Benton

 

thanks tim...that was great input...Ill tune it for regular driving then.

Im thinking about going motec...the pfc is frusterating me with its wierd idles and strange happenings...as well as the worthless support from their primary tuner in my area.

my car started idling like mad again today..vroom vrooom vrooom...temps went up to 112 on the commander for water temps....that scared the crap out of me. the loping idle of the pfc is random and frusterating...have any of you found a good solution to this problem?


j

j

 

have you tried the clutch switch? ARTGUY this is a common problem for idle flux, 40.00 dollars from the dealer located behind the clutch pedal, i doubt it is the PFC

 

Artguy, i strongly think you should give Excessive motorsports a call and have him tune it, (I beleive its number was posted awhile ago.) before you go motec. I truely beleive that Ralph can get that thing running perfect. He's truely amazing. CJ

 

Jason: You can look at the etc->function menu when it starts getting a bad idle. Look for the clutch switch indicator and see what it tells you. I have the feeling you need to let more air with you air bleed screw on the throttle body, adjust throttle cable tention, maybe adjust the dashpot for decleration control (on throttle body), and also maybe raise the fuel cut numbers slightly. You can get it smooth again. The acceleration hesitation at idle can be smoothed out by adjusting the accelerator maps on the PowerFC and perhaps the inj fuel maps in the PowerFC. Which maps are you currently running again? What are the values in idle area? The coolant fans (both) should be on high speed when you coolant sensor shows 112C ... is this the case? That would be a good indicator of a faulty coolant temp. The powerFC is going to pull timing at high coolant temps so I can see the idle fluctuating from that. I also have an older thread on igntion control at idle if you want to get more radical ....

 

I'm surprised you're having idle problems. My PFC has always idled perfectly once the factory set screws are properly set up. The problem you mentioned about the idle falling when you lift throttle may require adjustment off the damper. It's on the front of the TB, just adjust it to be fully compressed when the TB is closed, then back off a turn or so. This will slow the throttle plates as they close and result in less stalls. You can also increase the upper rpm PFC idle settings as a previous poster noted.

 

I hesitate to think the dashpot or "damper" is to blame for stalling or 400rpm... The main reason is because mine got stuck so I took it out and threw it (literally) away. No problems on deceleration or acceleration, or anything like that.
If I were you, I wouldn't ditch a programmable fuel management system for another because of an idle problem because the chance of the ECU randomly changing and affecting this is next to impossible. Check your TPS readings and make sure that you warm the car up first so the fast idle cam has separated. One of my 3rd gens had this problem, and it turned out that the TPS was so far off that it was stumbling on acceleration, stalling, and lit up the sensors on the sensor screen. Best bet is make sure that everything on your car is set up right especially in your throttle body.

Richard