Diagnosis, too lean?

[Tom Sawyer]

I've been doing this long enough to know the basics, I just want someone to help me understand the warning signs of being too lean. I have an EGT, S-AFC, and Pocketlogger to tune my OBDII car w/mods in profile. Right now I'm maxing at 1200F at the top of 3rd and getting a smooth timing curve to 18 degrees. This probably means low to no knock and I'm at -17% across the board on the hi-end of my AFC. Similar setups have run well at -25% and -30% so I set mine at -15% to start and went down 2% from there. I'm thinking I've got a fair amount more to lean out but the car runs good now with no problems beside the somewhat sorry gas mileage. If I can keep it reliable and squeeze out a few more ponies, let me know how I know when to stop pulling fuel. Thanks!

Tom

 

[candela]

if you want a nice tune then use a wideband.... if not then go by o2 voltage, EGT's and seat of the pants...sounds like you could lean it out a lil' more though...

 

[1LE]

If you notice that the timing flatlines instead of going upwards with rpms, you took out a little too much fuel. If timing goes DOWN as rpms go up, you took out WAY too much fuel and you might have to stop and pick up engine parts off the road if you don't shut it down ASAP!!!

 

[jdmawd]

Originally posted by Tom Sawyer
I've been doing this long enough to know the basics, I just want someone to help me understand the warning signs of being too lean. I have an EGT, S-AFC, and Pocketlogger to tune my OBDII car w/mods in profile. Right now I'm maxing at 1200F at the top of 3rd and getting a smooth timing curve to 18 degrees. This probably means low to no knock and I'm at -17% across the board on the hi-end of my AFC. Similar setups have run well at -25% and -30% so I set mine at -15% to start and went down 2% from there. I'm thinking I've got a fair amount more to lean out but the car runs good now with no problems beside the somewhat sorry gas mileage. If I can keep it reliable and squeeze out a few more ponies, let me know how I know when to stop pulling fuel. Thanks!

Tom

As long as timing is not being pulled and you are not getting excessive amounts of knock, screw EGT's. at the top of 3rd recent logs show 24* of advance zero knock and the egt gauge is pegged at 1600(thats as far as the gauge goes)

 

[paul s]

I running 21psi on 50trim and 94 octane, the timing is 15deg at 7000 rpm in 4th gear and the egts are at 1630f.