Having to add 35% fuel trim

Chappy · Post by **Chappy** » Wed Aug 05, 2009 1:40 pm

Hey everyone, I have a B18C1 JRSC running 6psi and I just got the s300 ecu and rc 440cc injectors.

After installing everything and loading up the map for a B18C with 12 ohm 440s the car wouldn't idle at all. Some of this was due to needing to invert the purge valve which I did. After that it idled very like like 500s and would die after stabbing the throttle.
While running in closed loop I saw that the s. trim was maxed at 47% and so I went ahead and tried adding some overall fuel trim to the map and ended up with 35% overall fuel trim to get the car driving well in open loop.
The car doesn't smell rich at all at 35% fuel trim (I don't have a wideband) but it seems like I shouldn't have to add that much extra fuel.

As far as things I have eliminated from being the problem:
-New FPR
-New Gas Cap
-New injectors
-New fuel filter
-less than 1 year old 255 fuel pump
-no vacuum leaks
-not improperly connected pcv or evap
-ECU is set up to run 440cc and knows stock is 240
-stock fuel rail but that should be enough for 440's I think

I just got a fuel pressure gauge and this is what I saw.
With 0% fuel trim the fuel pressure at idle is 43psi (which to my understanding is about the correct fuel pressure).
Once I up the fuel trim to around 30-35% and the fuel pressure is steady around 50psi (which to my knowledge is a little high for idle) and the car idles like stock.

I am thoroughly stumped on this one and I am hoping its something I'm doing wrong with the computer.

Thanks in advance for any input!

Post by **Spunkster** » Wed Aug 05, 2009 2:14 pm

you have not posted a datalog and the calibration you are using.

Are you sure you have 12ohm injectors?

Chappy · Post by **Chappy** » Wed Aug 05, 2009 3:08 pm

Sorry I was at work when I posted it...and I just got back. Here is the calibraiton and it wont let me upload the datalog right now I dont know why I will try again after dinner.

I have tried both the 16 and 12ohm versions and both had to be trimmed the same.
The injectors are the ones that came with the Jackson racing reprogrammed ECU kit.

I think the datalog I have is too big I will make another shorter one tomorrow and post it tomorrow morning.