Some history. I'm the original owner of an 89 Formula, LB9 motor, ALL stock except a SLP 3" cat back. 70000 miles. factory options =dual cats, performance rear with posi.

Multitec injectors shorted out, so I installed Accel 19 lb injectors. can ran fine most of the time, except above 4000 RPM it was starving for fuel, felt like a hiccup, or sputter. When cold, open loop, the motor was surging. definately lean symptoms. BLM's were 140-150 with the new 19lb injectors. this was with the factory prom & factory fuel pressure which is 47 psi.

I started questioning the 19lb injector law for 305's, and found a few sources who said 1989 and up 305's also got 21 lb, like the 350. I found 2 sources who swear 305's of certain years got the bigger injectors.

So I installed ACCEL 21 lb injectors, and the car runs much better. runs perfect when cold. runs above 4000 rpm's no problem. pulls hard the entire RPM range. The BLM's are lower, but still 130-140 !! (with 1 exception below) This is factory prom. I'm pretty happy with how she's running. but the BLM's are still high.. I could have gotten away with 22 lb injectors. This is all with the stock fuel pressure regulator.

So I am convinved without any doubt, 1989, LB9, N10 dual cats, performance rear, etc, etc. got big injectors. plain and simple. I know guys will flame me till no end, but I'm convinced. Don't go by the 19 lb rule.

This is another strange problem. I installed bigger injectors as said above, all cells, BLM's came down except cell ZERO, which is the idle cell. cell 0 BLM's went up with bigger injectors.
19 lb injectors, BLM Cell 0, idling, BLM 140.
21 lb Injectors, BLM cell 0, idling, BLM 150.
nothing else has changed to cause this, so I have no explanation.

All my other cells came down 10 points, except cell 0 which went up 10 points...

I can't explain this. But anyway. don't get hung up with the 19 lb injector theory.

and I have a set of 19lb injectors for sale. only 1400 miles on them. like new, $200.

Larry

 

Good info.

Wouldn't shock me that later 305s with the "high performance" factory options like dual cats and such might have gotten bigger injectors. The highest HP rating on a 350 TPI in an F-body was 245. The highest HP rating on a 305 TPI was 230 in the last couple years of production- only 15 HP shy of the bigger 350 motors.

I believe 350s used 22 lb. injectors, however, not 21. That might explain why you only dropped to 140 instead of down into the low 130 range in the BLMs.

If the computer is trying to fatten up the mix the most at idle, even with bigger injectors, my first guess would be that you introduced a vacuum leak somewhere in the process of changing out the injectors. No shortage of gaskets in a TPI system, that's for sure! Or maybe you just have a vacuum line that's split or not connected somewhere. Vacuum leaks typically show their biggest effect at idle where there is almost no air going into the motor past the TB- even a modest vacuum leak makes for a big change in how much air the engine is consuming.

 

THIS MIGHT SOUND STUPID BUT I HAD THE SAME PROBLEM,, HERES WHAT I DID. YOU HAVE TO RESET THE ECM.. BUT YOU HAVE TO ELIMINATE ALL RESIDUAL VOLTAGE IN THE CAR.. BELIEVE IT OR NOT, ALL THE CAPACITORS IN THE RADIO HOLD ENOUGH MILIVOLTS TO KEEP THE ECM ALIVE,, JUST DISCONECTING THE BATTERY DOES NOT KILL THE MEMORY. SO AFTER THE BATT IS UNHOOKED PULL THE HEADLIGHT SWITCH AND DRAIN ALL RESIDUAL VOLTAGE FOR A GOOD 1O MINUTES.. THEN HOOK BACK UP THE BATTERY. THE ENGINE MUST BE COLD TO DO THIS. START IT UP AND LET IDLE FOR 15MIN. DO NOT REV OR NOTHING THEN CHECK YOU BLM'S.. TRY IT MINE WENT FROM 145 TP 128 PERFECT STOICH

 

Get the 4 digit broadcast code from your ECM or Memcal and I will tell you what the factory size on your injectors was. I will give you a hint, I have NEVER seen a factory 305 calibration (1985-1992) that had anything other than 19 lb/hr programmed in it. I have never seen a factory stock TPI 305 have anything other than 19# injectors in it.

The most likely problem is either an intake tract leak before the maf, or a dirty or failing MAF. The larger injectors have bandaided the MAF problem.

ACCEL injectors = JUNK so the problem could also lie within the injectors themselves.

 

The prom is ANYX.
old ACCEL's are junk. They were Yellow.
The new and improved ACCEL's are made by standard and are just fine. They are silver in color. People cant get over the fact ACCEL solved their problems.

Explain to us how my LB9 motor with dual cats, the big cam, T5 and 3:45 gears take the same injectors as a peanut cam motor, without any preformance options.

 

My factory bin ACYD 1139.bin has 20.82 lbs. programmed in it's PROM.

This is a 1987 305 LB9 TPI 5-Speed with 3.45 gears, single CAT, California car.

 

I still won't touch ACCEL injectors, even the new ones. I trust RP and Motorcraft more, they are tried and proven. Hundreds of thousands of vehicles can't be wrong.

Its in the tuning. The peanut cammed engines with their TBI exhaust just don't inhale as much airflow. The MAF reads the air going into the engine and injects the corresponding amount of fuel.

8 x 19# injectors (rated @ 43.5 PSI), running @ 47 PSI, running a BSFC of .50 and 85% DC will feed 275 Flywheel HP.
----------
ANYX had 19.45 in both single and doublefire constants. I was unable to locate a copy of ACYD.

 

I couldn't find ACYD online either. I have it only because I pulled it off of my car's PROM.