[Paul]

Injector slopes or MAF ?

When I did mine I took a different approach. After chasing my tail for months with the flowsheet that came wth my MAF I decided to try something. I took the stock A9L curve and enriched the entire curve to reflect a 24# MAF. That alone worked MUCH better than the flowsheet Pro-M sent. Then I never touched the MAF it again.

I used my LC-1's in NB emulation and MOST of my hunting at idle issues went away, longtubes... gotta love 'em

I used the wideband / dataq aproach to tune the injector slopes and it's pretty much dead on. Moved on to injector timing, revisted the slopes.

A few WOT pulls from 900 - 5000 rpm in 3rd and viola LOAD was done.

So after all that and not getting any better than "close" by tweaking the MAF and finally nailing it by dealing with injector slopes, I wanted to give alittle something back to the site that has helped me greatly. Hopefully the above approach helps someone else and thanks for all the help fella's

[JuiceSC]

"When I did mine I took a different approach. After chasing my tail for months with the flowsheet that came wth my MAF I decided to try something. I took the stock A9L curve and enriched the entire curve to reflect a 24# MAF. That alone worked MUCH better than the flowsheet Pro-M sent."

Do I understand this correctly, you didn't change the voltage figures on the maf transfer, but used caledit to "richen" the curve? If so, this is exactly what I've been saying that even if two curves are identical in flow values, the eec seems to work much better if you leave the volts alone. (A9* eecs, not sure about later ecms)

As for which is better, here is the way I see it. For low pw/part throttle operation I tune by maf. Slopes have more of an impact on high pw operation.

As for idle issues, I still belive the key is in the maf transfer. How you convert your maf flow sheet also makes a huge difference. To put it simply, DON'T use CALEDIT, period. Use an excel sheet or EA. Anyone who has a good working tune dialed in, I'm pretty sure you would see an improvement in drivability by redoing the maf transfer using the ford factory voltage values and changing Kg/hr values ONLY.

[Chris Mureen]

Keep in mind that you should be running a FPR. The regulator changes fuel pressure based on vacuum. Geetign low slope set reasonably good is important for this reason too. I have played quite a bit with slopes and MAF curves. I even once had my slopes set identically.

I have found that if you get the high and low slopes close to correct (maybe 10% to 20% difference between) and then tune the MAF function, it works best. Don't forget the impact that the inj comp batt voltages plays also.

Chris

[Paul]

Keep in mind that you should be running a FPR. The regulator changes fuel pressure based on vacuum. Geetign low slope set reasonably good is important for this reason too. I have played quite a bit with slopes and MAF curves. I even once had my slopes set identically.

I have found that if you get the high and low slopes close to correct (maybe 10% to 20% difference between) and then tune the MAF function, it works best. Don't forget the impact that the inj comp batt voltages plays also.

Chris

Keep in mind that was not an all inclusive on how this car to the point it is now but a vague roadmap that worked for me. All of the EFI cars i've ever seen have an FPR ;) and yes the battery voltages were taken into consideration.

Juice, I did not change voltage values only richened the flow data. I believe i saw that idea in one of your posts so i decided to give it shot.

[Chris Mureen]

Sorry, Paul, I didn't read your first post very well and I see how my response might have sounded condescending. That wasn't my intent.

Your points are dead on. I was only trying to add that many folks forget what the FPR does (sort of like a bandaid) and the challenge tuning around it can cause. In addition, the other variables can really cause a nice headache.

Chris

[fireguy50]

many folks forget what the FPR does (sort of like a bandaid) and the challenge tuning around it can cause.

The regulator is NOT a bandaid, it equlizes the fuel pressure in relation to manifold vacuum. It makes tuning MUCH easier.

[Chris Mureen]

I certainly realize what the FPR does. But it also suffers from some of the same temperature, atmospheric, and linearity issues as an FMU. I would much rather have a FPDM that is controlled by the EEC than a FPR.

My option, WMMV.

[JuiceSC]

[quote="Paul]Juice, I did not change voltage values only richened the flow data. I believe i saw that idea in one of your posts so i decided to give it shot.[/quote]

I can't take the credit for this, it is Clints recommendation to do this. Once I tried entering the maf this way, I was sold on it. And about this time was when I realized that the maf is not really measuring idle airflow. The values in the first 5 points are used by the eec.