Please tell me why I am lean.

[Staytuned]

Here are my mods:

Turbonetics rebuilt balanced and ported T25, ported and polished o2 housing and exhaust manifold, Buschur Racing upper I/C with 1G crushed BOV, 1G 60mm throttle body, Greddy 24R FMIC, Buschur Racing full SS 3 inch turbo back exhaust, Magnecor plug wires, K&N FIPK.

Super AFC, -6 SS braided fuel lines with Earl's fittings, AEM fuel rail, AEM AFPR, Aeromotive fuel filter, Turbonetics manual boost controller, Blitz FATT DC 2 turbo timer, 255 lph fuel pump and stock 450cc injectors.

I have the set at 17 psi which of course tappers off at the top end. Base fuel pressure set at 43 psi with vacuum line removed. For some reason my fuel trims are +3-4% short term and +10-12% long term. My plugs look white almost and my EGT's at WOT where hitting 950 Celsius. I did some runs and logged my timing and I was getting very low timing from 3000 to 5000 rpm ( 2-3 degrees ) so I have had to add fuel to my Hi settings on the AFC. I added 4% from 3000 to 5000 rpm range and 2% from there to 7000 rpm. That seemed to help. But why am I lean in the first place?

Any idea's people?

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[99gst_racer]

Are you only lean at high RPM's?? It might have something to do with 17lbs of boost on stock injectors. I'm only at 14 lbs. and my injector duty cycle is almost 100%. If you are maxing yours out, it could cause you to run lean.

BTW - Your car looks bad-ass.

 

[Staytuned]

This the first year I have had this problem. I ran last year with no lean problems at all. This winter I did the fuel upgrades and the FMIC and Bam it is running lean. Why would any of those mods put me at a lean state like this? Fuel pressure rises like it supposed to and no CEL's to point to anything obvious.

 

[94TalonKid]

Did you check your injectors to make sure one or more are not clogged? Use your datalogger to do this, or pull off one injector connector at a time and it should effect the idle a good amount.

If that isn't the problem, then you just have to add more fuel like you did. I don't see why this is a bad thing. I have up to +13% in the top end on my SAFC with 550s, stock fuel pressure, and a 255 pump.

Dan

 

[Staytuned]

Yes but stock injectors, stock ECU, stock turbo should not yield a lean mixture with very high EGT's. All four injectors look exactly the same not just the one I showed in the picture. Like I said this condition did not occur last year with stock fuel lines and stock fuel rail, stock side mount IC and stock 2G throttle body. These mods surely can't be causing this problem.