Went to the dyno today...fuel issue FML. need assistance
04-13-2011, 05:14 PM
#1
4th Gear Member
Thread Starter
Join Date: Apr 2008
Location: mi
Posts: 1,087
Went to the dyno today...fuel issue FML. need assistance
went to get the car dynoed and when he started to get on it the a/f tipped in and richned up but then when the rpms got up there it leaned right out to like 16. he tried everything opened the injectors to full and messed with the transfer function and still no fuel nothing...
running dual cobra pumps with dual fpdm's with a 40amp BAP with brand new 60's and a pro m maf calibrated to 60's with the 30 pt transfer function sheet.
i got home and changed the fuel filter(was replaced a year agao but did it neways) and dropped the tank and checked each individeal pump. both prime. put the fuel line that connects into the fuel filter into a bucket and tried both pumps individually both shoot fuel out the same and jets out alot of fuel with both.
hooked up a fuel pressure guage to the shrater valve and was seeing 30psi at idle. i dont know if thats correct or not. (think it should be 55psi driving but not sure about idle.) reved it to 3500rpm at a standstill (no load on the motor) and it maybe hit 35psi.
i dont understand wats going on. it seems like i have checked everything. i dont know why its leaning out im so bummed.
brighter note turbo spooled right up no leaks just the damn fuel issue.
running dual cobra pumps with dual fpdm's with a 40amp BAP with brand new 60's and a pro m maf calibrated to 60's with the 30 pt transfer function sheet.
i got home and changed the fuel filter(was replaced a year agao but did it neways) and dropped the tank and checked each individeal pump. both prime. put the fuel line that connects into the fuel filter into a bucket and tried both pumps individually both shoot fuel out the same and jets out alot of fuel with both.
hooked up a fuel pressure guage to the shrater valve and was seeing 30psi at idle. i dont know if thats correct or not. (think it should be 55psi driving but not sure about idle.) reved it to 3500rpm at a standstill (no load on the motor) and it maybe hit 35psi.
i dont understand wats going on. it seems like i have checked everything. i dont know why its leaning out im so bummed.
brighter note turbo spooled right up no leaks just the damn fuel issue.
04-13-2011, 05:34 PM
#2
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
Are you still running the stock returnless fuel system? If so then 30psi at idle is normal
Monitoring the rail pressure under load at the higher revs will tell you a lot--if the pumps and BAP can't supply enough fuel the pressure will drop as the mix goes lean.
MAFs are not really calibrated to any specific injector capacity, but rather to a specific injector and tune, usually a stock tune, its a kludge left over from the days when tunes could not be changed.
However since you have the transfer function (entered into the tune I assume) that doesn't matter.
I don't know what "opened the injectors to full" means, do you mean that he played with the low and high injector slope scalar values? Making them smaller will richen the mix, as the PCM's thinking they are smaller than they really are will cause it to calculate a longer pulse width to get the amount of fuel it wants--which will be more than it wants as the injectors are really larger than it believes.
One other possibility is that the stock PCM can only read airflow values of less than 1740kg/h (3830lb/h) unless the standard air charge, MAF transfer, and injector slopes are scaled.
This is around 560fwHP, 475 or so at the wheels--you may have hit that limit?
Can you post or send me the MAF sheet?
Monitoring the rail pressure under load at the higher revs will tell you a lot--if the pumps and BAP can't supply enough fuel the pressure will drop as the mix goes lean.
MAFs are not really calibrated to any specific injector capacity, but rather to a specific injector and tune, usually a stock tune, its a kludge left over from the days when tunes could not be changed.
However since you have the transfer function (entered into the tune I assume) that doesn't matter.
I don't know what "opened the injectors to full" means, do you mean that he played with the low and high injector slope scalar values? Making them smaller will richen the mix, as the PCM's thinking they are smaller than they really are will cause it to calculate a longer pulse width to get the amount of fuel it wants--which will be more than it wants as the injectors are really larger than it believes.
One other possibility is that the stock PCM can only read airflow values of less than 1740kg/h (3830lb/h) unless the standard air charge, MAF transfer, and injector slopes are scaled.
This is around 560fwHP, 475 or so at the wheels--you may have hit that limit?
Can you post or send me the MAF sheet?
04-13-2011, 05:59 PM
#4
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
BTW, if anyone has a MAF map of less than 30 points (which is what the EECV tune wants), I have a regression analysis application that can make a 30-point map from one with fewer data points--just give me a yell...
========================================
Blk03' one other thought, when the MAF curve was entered into the tune were the MAF output voltage for each of the 30-steps also entered from the data sheet, if different than the OEM steps. I have seen a couple of tunes where only the flow numbers had been entered, however they were at different voltage steps which really messes things up...
04-13-2011, 06:21 PM
#5
4th Gear Member
Thread Starter
Join Date: Apr 2008
Location: mi
Posts: 1,087
i think i only hit like 230whp cuz he couldnt bring it up becuase of the fuel issue.
the tuner is using sniper delta force to tune if that helps cliffy.
he made it seem like he made the injectors run full out 60lbs to alleviate that as a problem spot.
he was messing around with the transfer function stuff too. let me know any specific questions and il ask him tommarow.
the tuner is using sniper delta force to tune if that helps cliffy.
he made it seem like he made the injectors run full out 60lbs to alleviate that as a problem spot.
he was messing around with the transfer function stuff too. let me know any specific questions and il ask him tommarow.
04-13-2011, 06:31 PM
#6
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
i think i only hit like 230whp cuz he couldnt bring it up becuase of the fuel issue.
the tuner is using sniper delta force to tune if that helps cliffy.
he made it seem like he made the injectors run full out 60lbs to alleviate that as a problem spot.
he was messing around with the transfer function stuff too. let me know any specific questions and il ask him tommarow.
the tuner is using sniper delta force to tune if that helps cliffy.
he made it seem like he made the injectors run full out 60lbs to alleviate that as a problem spot.
he was messing around with the transfer function stuff too. let me know any specific questions and il ask him tommarow.
04-13-2011, 07:01 PM
#7
4th Gear Member
Thread Starter
Join Date: Apr 2008
Location: mi
Posts: 1,087
HOw do I get the tune code and box code? That would be awsome because I really think the issue is in the tune. Im scanning my transfer function sheet now. They tune alot of ls motors. The guy is really knowledgable they had a few million $ boats they were tuning and a tt viper. I just for some reason think its in the tune
04-13-2011, 07:06 PM
#8
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
HOw do I get the tune code and box code? That would be awsome because I really think the issue is in the tune. Im scanning my transfer function sheet now. They tune alot of ls motors. The guy is really knowledgable they had a few million $ boats they were tuning and a tt viper. I just for some reason think its in the tune
