I've got a 2005 mustang gt that I just installed the on3 70mm turbo kit onto and am have a few question about tunging the fuel curve to address my lean condition under load. I have installed 60lb seimens deka injectors, mafia and 340lph aem stealth fuel pump as supporting mods
I have set the injectors up using specs from ford racing 60's as no one seems to agree or even have all the specs for the SD's so that may be a portion of my problem but I had to start somewhere.
I have not done anything to account for the new fuel pump. I haven't noticed any tables that seemed appropriate to update due to the high flowing pump. It flows 340@43psi and I believe the mustang is suppose to have 39psi stock. If anything this should be giving me a richer fuel mixture but I would like this to be correct if it needs to be addressed.
I suspect my issue lies in the MAF. I am using the stock MAF with the help of the mafia range extender set on 3. The correction multiplier I've listed below comes straight from diablo but multiplying mag maf value by .59 seemed like it would lean out the mixture even further. The stock setting at 5volts is something like 303g/. what I did to scale the table is multiplied it by 1.41 to bring the max value (5 volts) to 427g/ so it would register more airflow at each voltage level. Did I do that correctly?
Setting Correction Factor Range Notes
0 No tuning required Stock Stock/No Change
1 No tuning required Stock minus 5% Leans Signal
2 24% or multiply by .76 5.5v – 5v or .90 Tuning Required
3 41% or multiply by .59 6v-5v or .83 Tuning Required
4 53% or multiply by .47 6.5v-5v or .77 Tuning Required
5 62% or multiply by .38 7v -5v or .71 Tuning Required
6 70% or multiply by .30 7.5v – 5v or .67 Tuning Required
7 No tuning required Stock plus 5% Richens Signal
To make matters worse, the charge pipe that I have the maf installed in is 3" diameter and I suspect the stock intake piping was larger which is further throwing my maf calculations off. Once I find someone who will let me measure the stock diameter I plan to use an "area of a circle" calculation to find the difference between the 2 and multiply my maf files accordingly.
I have only done a couple miles of street driving to figure out what areas need tuning it seemed that as the engine warmed up the lean condition worsened. At idle I had 11.8-12.2 which although rich I though was at least a safe place to start. I was only able to accelerate under very light load (not even enough to get to drive speed limit) where my wideband was showing 14-15 afr. Any harder and afr would jump to 18.
I have read else where it is a good idea to tune in open loop before enabling closed loop. Is this a good strategy? From what I can see (newbie tuner), the main table for influencing the fuel curve are the "maf airflow vs voltage", and the "injector offset" (I'm at work and going off memory). I know there are multipliers and tip in's but are these the 2 main areas to get it to at least stay under 18 afr?
Can someone also please explain "Load with failed MAF"? I don't like to change things unless I have at least a rough understanding of what I'm doing. Throttle % and rpm are the 2 axis but I cant figure out what the values are that make up that table.
thanks,