Down grade to 24lbs injectors??
- Thread starter deepsea1969
- Start date
S_Charged306LX
Founding Member
i am running 19lb injectors on almost exactly the same combo except for that i have TF heads. on the dyno my car did not look like it was going lean any time
soon, maybe you are overkilling it a bit switch down might not be a bad idea cause i thought of puting 24lb ers on mine.
soon, maybe you are overkilling it a bit switch down might not be a bad idea cause i thought of puting 24lb ers on mine.
S_Charged306LX
Founding Member
well, it seemed to run like it wasn't getting enough fuel, so I pulled the spark plugs and they were white. Indicating a lean condition. Checked fuel pressure it was at 39. Plus my gas mileage was around 11mpg and I didn't drive it hard. That was city. Increased fuel pressure and seemed to fix the prob. a bit. So I was thinking maybe the computer was having a hard time and thus causing it to be lean.
gt40_2003wes
I did sound a wee bit gay there.
Michael Yount
Mustang Master
I run 19's as well with a mild h/c/i combo. You can't rely on plug reads to tell you much meaningful on the newer efi cars. The computer is DESIGNED to run them as lean as it can get away with to save fuel. The egr system allows the computer to pull fuel (lean) and add timing - to save fuel and improve emissions. An efi engine in perfect working order will almost always show bone-white plugs. I did a guilt plug change on my wife's Bimmer at about 65K miles -- except for grime in the threads, I could barely tell the 7 year old/65k plug from the new one.
If you're wondering about a/f ratio - get some dyno runs with a wide band. That'll tell you much more about your a/f ratio than plug reads will. Plug reads are fine for leaded racing fuel and carbs -- but even many of those guys use a/f meters to tune with.
30's are way more than you'd ever need with your combo. 24's are plenty; 19's are probably just fine.
If you're wondering about a/f ratio - get some dyno runs with a wide band. That'll tell you much more about your a/f ratio than plug reads will. Plug reads are fine for leaded racing fuel and carbs -- but even many of those guys use a/f meters to tune with.
30's are way more than you'd ever need with your combo. 24's are plenty; 19's are probably just fine.
Michael Yount
Mustang Master
You and I are running an almost identical combo - you have stock cam, I have a mild custom. I run a ProM 73 mm maf set up for 19's. Mine actually ran a bit rich on the dyno - we had to use the chip to take out a bit of fuel. 24's are plenty; 30's are big time overkill; 19's will likely be fine. Your biggest challenge is getting an accurate maf signal with that C&L maf. Keep your fuel pressure stock.
Michael Yount
Mustang Master
If you're gonna keep modding, put the 24's in. By the way, if it's running ok, and the a/f is ok, why not just stick with the 30's since they're already in there?
I wish I would have went with 24's instead of listening to the bigger is better crowd. I have 30's on a more "steppedup" setup than you and they run rich but I get good gas mileage. It causes hot start problems due to too much cranking fuel. Also a nice rich idle...
One guy actually swapped from 30's to 24lb injectors (swapped sample tubes I believe) and gained some at the track. It was a small amount...that could have been changed from anything but the overall leaner condition could help that. My car would run happier with 24's. I know that.
One guy actually swapped from 30's to 24lb injectors (swapped sample tubes I believe) and gained some at the track. It was a small amount...that could have been changed from anything but the overall leaner condition could help that. My car would run happier with 24's. I know that.
Michael Yount
Mustang Master
87 - if it's a dry shot, I'd run the 30's.
Stang619 - I think a lot of it has to do with how the car is gonna be used. If it's a street car - 95% of your run time is spent with the injectors barely being tasked at all. I'd go with 24's in that case on a combo like yours. If it's a dedicated racer where almost all time is spent at w.o.t. between 4000-6500 rpm, then I'd probably put the 30's in it so the injectors aren't working so close to their max limit.
Stang619 - I think a lot of it has to do with how the car is gonna be used. If it's a street car - 95% of your run time is spent with the injectors barely being tasked at all. I'd go with 24's in that case on a combo like yours. If it's a dedicated racer where almost all time is spent at w.o.t. between 4000-6500 rpm, then I'd probably put the 30's in it so the injectors aren't working so close to their max limit.
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