2000 K3500 7.4 help injectors too big

[SS540CORVAIR]

I recently installed a new set of Accel 26# injectors in my 2000 K3500 7.4 crew cab dually. I should have researched better on what size the original ones were. It runs and drives but it is running extremely rich through the entire range. It seems to be less noticable at 70 mph than 35 or less. What I need is options to lean it out and tune it up for a free flowing exhaust (full 3" with dual FlowMasters all the way to the bumper). Thanks for any help you can share.

[joecar]

Do these flow 26 lb/hr at 43.5 psi...?

What are the specs of the original ones...?

[SS540CORVAIR]

Yes the 26# is at 43.5 and from what I found out so far the fuel pump in the truck is 55# and I was told the original ones are 19#.

[joecar]

You mean the rail pressure is 55 psi...?

Does the fuel pressure regulator have a manifold vacuum reference hose...?
If it does, then rail pressure has to be measured with the reference hose temporarily disconnected from the FPR while engine is idling.

Say rail pressure measures 55 psi (with reference hose disconnected), then:

calculate IFR = 26*sqrt(55/43.5) <-- this gives injector flow rate in lb/hr; to convert to g/s, multiply by 0.126.

paste the calculated IFR into all cells of your IFR table (IFR table should have come with same value in all cells, right...?).


[ remember to reconnect the hose when done measuring ]

[SS540CORVAIR]

joecar yes the 55 psi is with the vacuum disconnected and I follow the calc but I need to know if I can reprogram my ECM or do I need to find a different one. I have worked with Accel DFI and some others so I some what capable of making the changes. I don't have much knowledge in the factory ECM's and what it take to make the changes I need to correct the injector size problem. Thanks for the help

[joecar]

Connect to vehicle, start the EFILive tunetool, and then:
- key on,
- read PCM (select PCM type first), and save to file,
- key off,
- search for B4001 (Injector Flow Rate),
- edit all cells of B4001 to the caculated IFR value,
- save file,
- key on,
- flash calibration only (not the operating system),
- key off
- wait 15 seconds.

Make sure vehicle starts.

[joecar]

If your PCM is not supported, then you won't be able to read the PCM.