I have moved up from 19# injectors to 24# injectors,what else do I need to change in the eprom besides the injector size? Do I need to add more MAF?
Thanks
Tom

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86 IROC T5
MSD 6A
Summit cam
Flowmaster
AFPR
Lowered 1.5"
My own prom (finally)

 

Yes. If the pressure remains the same then you only need to change the injector constant. However, those 24lb/hr injectors that you mention ... what brand are they? SVO 24lb injectors really flow 26lb/hr when rated according to GM's Fuel pressures.

Leave the MAF tables alone for an injector swap.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Trax, these injectors are from TPIS. The are supposedly matched.

------------------
86 IROC T5
MSD 6A
Summit cam
Flowmaster
AFPR
Lowered 1.5"
My own prom (finally)

 

I think you are best to do a scan on the engine regardless, to determine what your overall injector flow is. Many people have adjusted their fuel pressure, which has the same effect as putting on different flowing injectors. Even if you haven't put on an AFPR, there can be a variation in fuel pressure just from car to car.

I found that I had to increase my Injector Flow Constant to 25#, and I only have 22# injectors. This is partially due to my higher fuel pressure (only 46 psi), but also I found the GM chip is overly rich. I suspect this is because GM thought it would be less costly to error on the side of over rich than over lean on its calibrations.

When I was analyzing my engine, I found 25#s got me the closest to the "original" VE tables thought they still required extensive changes to get me optimal. BTW, I tried MANY combinations, and this is the constant that worked the best and got me the closest.