maxed out injectors?

Ive had a bad stumbling problem around 4K and found the problem has to do with adjusting the boost at the gillis valve. I screwed the valve out(lowering boost) from 15psi and the hesitition is gone. Its now at 11psi and is pulling great. Fuel pressure adjustments did nothing for the problem. Considering my mods listed below, does it sound like Im maxing out the stock injectors?

It could be ignition related. Make sure the wires are motorcraft and the plugs should be autolite 103s at .028. Other than that it could be compressor surge depending on the trim of the turbo. My 57 trim would surge right around 4k at high boost and full throttle. It sounded like a rattle snake sorta. Also check the couplers for rips or tares.

i would say no. possibly compressor surge. what trim is the turbo ? or maybe the bov is leaking. check for boost leaks. maybe eliminate the bov and retest. just some thoughts. good luck Andy

I'll pull the plugs later and check the gap. They are Autolites but I dont remember the number. The wires are motorcraft and are a year of so old, but dont have many miles on them. As for the BOV leaking...is there a universal procedure for setting the spring tension?

I would take the bov right out to eliminate it and see what it does. do you have a w/b 02? could be going really fat at that rpm also. does this problem clear up with more rpm or is it from 4k rpm and up ?

You have a wideband so if it was lean before (progressively lean, not just all the sudden spikes to 15:1 or higher) and isn't now at lower boost then it's out of injector. If it spikes lean and seems erratic, it's spark blowout from weak ignition components or too much gap.

The problem starts at about 4K and continues up to 5K. Youre correct Shannon, it would never spike to a lean condition. It was always progressive. I havent went past that point(5Krpm) when its leaning out. Yeah, with the gillis set at 15psi, it was leaning out as far as 12.5 or so. Any more than 11psi(where its set right now), it will lean out and hesitate and such. Is my turbo(Turbonetics T3/T04B) capable or maxing out a 35lb injector at only 12psi? Must be huh? I'll pull the plugs asap and check the gap and condition. Thanks for the help!

I doubt u are maxing out the injector at 12psi with that turbo. If it is fuel related it could be the regulator, pump, or a tiny chance its the fuel filter blocked up. I still think boost leak, compressor surge, or spark blowing out.

Originally posted by longbedGTs:
Youre correct Shannon, it would never spike to a lean condition. It was always progressive. I havent went past that point(5Krpm) when its leaning out. Yeah, with the gillis set at 15psi, it was leaning out as far as 12.5 or so. Any more than 11psi(where its set right now), it will lean out and hesitate and such. Is my turbo(Turbonetics T3/T04B) capable or maxing out a 35lb injector at only 12psi? Must be huh? I'll pull the plugs asap and check the gap and condition. Thanks for the help!

12.5 isn't lean, that's near the top of the "safe" range though.

IF you are running short of fuel flow (barely) then a little more fuel pressure should fix it.

Well, I just pulled the plugs and they look normal but were at .050! Is it a pretty safe bet that the spark was blowing out? Im setting them to .028 as bangforthebuck suggested. I also went one full turn to tighten the spring on the BOV. I took it for a drive at 11psi and it was fine so I upped the boost in small incriments. It is now back at 15psi and there are no signs of hesitation...however, with the FP set to 41 lbs, the afr reads in the high 11s. At 15psi, is that a safe ratio or should I raise the FP until it reads full rich? Whats the ideal afr at 15psi?