After you get you car AFR tuned for power at boost, work on the cruise and transition areas.

Above idle in cruise up to 90MPH, I run about 16AFR. Better mileage and cleaner exhaust. From those P rows (about P6) up to 0PSI boost/vacuum(P10), I adjust to about 14.7AFR. When you hit the gas, boost goes above 0 PSI boost almost instantly, thus I consider anything below 0 boost as cruise or light acceleration.

Now here is something most people never mention or tune: the area from 0 PSI boost to your first tuned boost row.

My lowest fully tuned row is P17 (12PSI). Here I run 11.5AFR. I never run below 12PSI boost. At 0 boost which is P10, I am at 14.7 AFR.

I make mediumthrottle runs starting from cruise at 3K, 4k, and 5K up until I hit P17. Then I adjust P11 - P16 so tha AFRs lineraly increase from 14.7 to 11.5. The results is something like this.

P10 0 boost, AFR = 14.7
P11 AFR = 14.5
P12 AFR = 14
P13 AFR = 13.5
P14 AFR = 13
P15 AFR = 12.5
P16 AFR = 12
P17 12PSI boost, AFR = 11.5
This gives good mileage and very smooth transition.

Then I am somewhat of a perfectionist and do not mind spending a lot of time on my car!

 

nice work, do you have it set up to compensate for cold weather too? (using the intake air temp sensor or something?)

 

First off; I have moved my ATS from the UIM to my IC outlet to increase accuracy in measuring the true air temp. Here it also heat soaks less.

The PFC has too wide a range of "AIR vs INJ" points in that map for my likening and you only can change the correction values but not the points. The temperature points are in C; 80, 50, 30, 10, -10, and -20.

Tune much as possible of you fuel map and rec-calc under the same temperature conditions. Then do not do any more tuning until the temperature changes enough to pass the adjacent point, then retest. Adjust the next point so the AFRs match the previous test.

Example. I tune when my air temps are very close to 30C /86F and keep my last test. Then when my air temps drop to 10C/50F; I repeat the saved test. But this time only adjust the 10/50 point to correct the AFR back to the 30C level.
This way the AIR vs INJ map is keeping balance for temp changes.

Do the same for the other points around the original 30C , Now you see why I say the spread is too large. Here in Houston, my highest air temp is about 45C and my lowest about -1. Thus I am only using about 46% of the map.

Note: when changing a value by x%, the AFR will also change by that amount for my PFC. Thus if at 10C I need to increase fuel by 3%, I increase the correction value by 3%.

 

Chuck,

This is great information - I wish I had a datalogit and wide-band, I'd be out there right now dialing my car in....

Couple of questions for you....

Now you have your car dialed in this way, what kind of mileage are you getting on average with your car? Are you concerned at all about running so lean under no load?

What mods do you have - specifically fuel, injectors and Turbo?

Russ.

 

I am not running lean under load, only under cruise. I have been running these for over two years and the only high knock readings I ever had were when on strong boost, and it was due to timing being too advance for the fuel/weather conditions.

My closet tunning buddy also runs about 16AFR for cruise.

You tune you car as I said, but also look at knock levels which is a topic I have not mentioned.

 

Do you remember what you plugged the hole with under the intake when you moved the Air temp sensor ? What threads did it take in the Elbow ?

Tom

 

I just recently picked up a new battery for my laptop and as soon as I have time, I'll start tuning my car. I can't wait. One thing I must say is that the datalogit does take a little time to get use to. I'm one of those guys who does'nt read the manual until after he's played with it.

Chuck, what size of injectors are you running in your car? I'm running a 850/1300 setup and can't seem to lean my idle out more than about 11.5 a/f. Its just like the car does'nt respond/injectors are to big. CJ

 

I am at work now so I do not have the info, but: It is the same thread as our bolts with a 12mm head. Probably 1.25 by 9 or 10 mm. I use a short bolt to fil the hole.

 

I run 550/1200 with stock non-seq, at 347RWHP at 15PSI boost my ING duty cycle was about 84%.

To tune your 850 prijaries, you might also have to give it a negative lag to lean it out more.

 

i can't thank you enough for your contributions to this forum cewrx7r1.

 

Great thread. Thanks, Chuck.

 

Thanks Chuck. I'll give that a try when the rain stops coming down. CJ

 

"i can't thank you enough for your contributions to this forum cewrx7r1."

I also agree with you about Cewrx7r1 - Chuck. You will notice that he doesn't have anything smart *** to say, no negatives upon someone's car constantly, or bashing about. That makes for a good Forum, just polite good to use data that can help someone enjoy the work on an Rx7. I appreciate his answers to my questions. This is how we learn.This forum needs more chuck's.

Tom

 

Chuck,

Great info. What lag setting and other injector settings are you using for your 1200's. Thanks for all your input on the forum.

Ken

 

Did you check your TPS? If it is out of range, then the PFC goes to a default and you will not be able to adjust your idle mixture. You can make it idle just fine with 850's.

 

.10 lag.

 

ok, i have the apexi turbo timer and with it it comes with a a/f ratio display. nad it shows that i have a ratio of 2.6... what do i do to adjust the a/f ratio. and are we talking abotu the same numbers

 

No, you can't use the Turbo timer a/f readings....you must have a true wideband o2 sensor setup like the Techedge or FJO.

You adjust the AFR by adjusting the fuel maps in a standalone, programmable ecu like the Apexi PFC or Haltech.

 

Ok so I just got a wideband sensor and I'm currently running a M2-stage 3 but am thinking of getting a power FC so I can run 12 psi. Do you think I need a datalogger or do you think the base mod map would be close enough to just tune-by-eye over time and normal driving...