I have dialed in my fuel map to my desired AFR's (11.2) from 3-7300 RPM. My question is this. If I add fuel at a certain RPM is it neccesary to add it in all of the load sites are just up top? As of now, when I added fuel I did it from 10-100 load sites. It seems like overkill to me. Should I back off slowly at the low load sites until AFR's change or is there another trick to this? Sorry for the convoluted question.

 

You should only be making changes to the load sites you are traveling through. If you are changing values without valid merit it's not called tuning

Thanks,
Jermaine

 

If this is the correct way to do it than it means that fuel corrections should happen at 2 load sites at most, per any given RPM. I have not seen many fuel maps that look like that. I may be confused

 

Well, I think he meant that the tuning part of it means you try runs at different loads and speeds and gears so you get valid entries to enter into the fuel/timing maps..

Its funny because a third gear run you may get 60-70-80-90% but in fourth gear, you may go through 40-50-60 etc.. so after a few tuning runs, you will have enough information to fill the cells to be appropriate to the different curves you go through..

Or something like that..

 

Duh I was only thinking about one gear. I seem to have forgotten that we have 4 others. One more Question. Does a map sensor allow for better representation of load sites? I do not have one yet and I was just wondering?

 

Ok.. that is a bit up in the air.. using MAF will represent the actual air demand of the engine.. HOWEVER the maf is easily fooled by intake changes and other weird things.. so using the MAP results in a smoother predictable ramp where your not jumping back and forth between load sites as MAF jumps due to turbulence.

If you have a MAF reading that is very stable and fairly smooth, then you are better off using MAF.. For most of us, using MAP will result in a smoother curve (Plus WAY more consistent)

Please be aware that just using MAP and TPS instead of MAF removes the advantage of using MAF which is being aware of the true air density.. But in practice it doesn't seem to make much of a difference unless you are dealing with serious changes in altitude or air pressure.

 

A map sensor will allow you to travel through load sites is a smooth almost linear fashion. I like tuning map vs. rpm than maf vs. rpm but both ways are effective.

Thanks,

Jermaine~
www.turboxs.com

 

Since switching back to my stock air box, the MAF frequencies are stable and smooth. So I guess I will hold off on the the MAP sensor for now.

 

I have seen a lot of maps with fuel corrections in the 10% and 20% load sites at high RPM's (6-7K) So are you saying that this is pointless since you will never be in the load sites at those RPM's. I understand the logic, but since there have been many Maps posted here that looked like that, I thought that this info may benefit a lot of people.

 

Actually you will occasionally hit those load sites at high RPMs.. especially in road racing or running through the gears..

 

Some places in the map are nearly impossible to get to like the 100 percent load column at 1500 rpms. So you can have a value there but I wouldn't say that area is tuned.

Also high rpm low load site areas are traveled through, alot more than you think. When you are tuning you are typically driving a way that you don't normally drive so it's hard to see what load sites you are really traveling through.

Thanks,
Jermaine~

 

Yep, thats why you need to log alot of driving data after you get your base curves set for the different gears and make refinements.. I generally log my entire drive home so I can get a few different load references and load sites... a few high load part throttle runs, a few WOT runs through the gears, etc... I don't attempt that until I get a rough map that is safe enough to not cause damage (conservative timing and rich mixture) and then fine-tune over the next day or two..

 

I would not know where to begin with part throttle tuning. What AFR's do you target for part throttle tuning?

 

Depends on the engine load and boost levels.. you can target 11.5 afr's if its comfortable.. This is the kind of part throttle driving where you will get fairly high boost, and your in open loop fuel control.. so its not a fuel economy thing.. you really just want to get AFR's in line with the timing and engine loads you will see..