Basic overview of my car: Stock motors, 550/1300 walbro tuned by neptunespeed at 13psi. Car is great at wot. Pulled 330whp @ 10.8 afr. The only thing I want to tweak is my idle and driveablility.

I have a wideband (LC-1) but no data log. If need be I can barrow one from my friend. My idle varies from 12.8-13.1 depending on weather. Too rich . So is there a way I can lean out my idle through PFC? Whats a good idle AFR? I think this may sort out my cars tendency to be alittle hesitant studdery at low rpms.

Thanks a lot guys

 

the little driveability problems you are describing are IMO the hardest part about tuning. And that's tuning on any car on any EMS really, I've messed with a few. It's really difficult to get a car to drive like it was stock, and it only makes me appreciate just how much time and money goes into OEM tunes.

Your idle is actually pretty good. Without an air pump, the 12.5-13.5:1 range is best for a balance of idle stability and fuel consumption. You could make it slightly leaner but if you're not careful you will find the idle surging and the car actually running worse. The tip-in problems you are describing could be the fuel map, it could be TPS calibration, or it could be one of several tip-in adjustment tables. You really need a datalogit before you can do a whole lot.

 

10.8 AFR is on the rich side for 13psi boost but is very safe if you cooling system and IC are not optimized. 11.2 AFR is normaly still very safe for 13psi boost.

I run 10.8 AFR for 16psi boost with a GT35R turbo.

 

I agree. That is not that rich and will not be causing the stumbling you are having. You won't be able to lean out your idle anymore then about 14 .1 and it will run a little stronger in the 12.5 -13ish range. You will probably not be able to get your car to run much better without a datalogit. That also goes for leaning out your idle. My guess is you have taken as much fuel out as the pfc will allow at idle without introducing some different lag times using the datalogit. You can always try taking some fuel out with the commander to see what happens to your idle afr but even if it did get a bit leaner this will not help your hesitations. I also agree that your boost afrs are too conservative. Even the numbers chuck mentioned are still considered on the conservative side. You have more power to be made!

 

Tip-in stumble is rarely due to a rich condition ... cars tend to run a bit lean on tip-in once we upgrade/change the intake tract.

On idle Chuck has done some nice work on timing and fuel, if you plan to get a datalogit then read his posts and get his notes and it will help you improve your issues. Otherwise, find someone knowledgable to get the driveability issues tuned right.

 

Here is my dyno. I might go back and get a retune for $150 and ask him to tune to 11.0 afr. The problem is that his dyno dosent have load control and dosent even show #'s. This dyno was done by a locar Dynojet. Im going to ask him to do a street tune, maybe that will clean the map up alittle.

Another thing I want to add, Do you guys experience a hickup when de-accelerating from 2.5k down to about 1.5K rpm? As if the the engine releases load and the car kinda jurks. I believe I have a bad transition in my map. I thought it was my idle, and the map shifts to close to idle rpm's.

I will definitely let you guys know with results. I know this is a common issue.

btw multiply my tq x 2 and divide my rpm x 2.

 

Even with your torque * 2 and rpm / 2 correction, I have never seen such a flat torque curvecfor a stock port motor. Seems a little fishy???

 

I don't trust that dyno sheet at all. He didn't set it up properly... he didn't even know to hook the inductive clamp to the trailing coil and set it to 4 cylinder. And those graphs are confusing in the way they are set up.

Ask him to e-mail you the .drf files from the dyno runs. Then download WinPEP7 from the dynojet website and load it up yourself. That's what I did after my dyno runs. It takes about 15 minutes to figure out how to use the software.

 

I did the runs a long time ago without hks twimpower. The car was only boosting 12psi since my air temps were 55+. Ill see if he still has the dyno runs. Besides the power, you guys do agree that my AFR according to the graph seems low correct?

I actually noticed my idle is at 12.1 not 12.8. I think my A/c might of been on or something last time I checked. With the commander, how should I adjust it? Wish my instructions werent in Japanese.

 

For hot idle and cold idle start, never use AFR, adjust for slightly richer than smooth leaness running by ear and rpms. If N1 to N2 fuel gives me the highest rpms for the air/timing combination without the revs dropping off, then I use a value between N1 and N2 but closer to N1.

Cruise is done by AFR then richen up if a lean spot occurs (usually around 55mph and caused by the secondary throttle starting to open.) I run reacher close to idle and lean out to my fuel around 3000 rpm to my goal (16.5 - 17AFR).

I only do boost by pure AFR.

 

well I adjusted my idle to 13.1-13.4 (went to inj map and through the map tracer i just lowered the block which my idle is at) . No big differnce. I does sound alittle smoother but that could be in my head. Still pretty jittery at lower RPMs. Again, im going to schedule a street tune and ill let u guys know what we change.