LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Upgrading fuel injectors. What do I tweak in my tune?

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Old Oct 6, 2008 | 11:17 AM
  #1  
wrd1972's Avatar
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Upgrading fuel injectors. What do I tweak in my tune?

Replacing my 30# injectors running at 90% DC with 37# injectors this weekend.

I know there is a parameter in the tune that must be changed to account for this. I have the ability to tweak my tune until I can get it to the dyno and get a good dyno tune..

What is this parameter and what should i set it to to get me by in the short run?
Old Oct 6, 2008 | 11:52 AM
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Just the injector flow rate needs changed, nothing else.
Old Oct 6, 2008 | 11:52 AM
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You need to change the "injector flow rate". If the new injectors are rated for the same fuel pressure as stock, set the flow rate to 37.
Old Oct 7, 2008 | 07:55 PM
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What is "display injector flow rate"?
Old Oct 8, 2008 | 11:27 AM
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Originally Posted by wrd1972
What is "display injector flow rate"?
It's for the "DIC" fuel mileage readings in the Y-bodies.
Old Oct 8, 2008 | 02:45 PM
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Originally Posted by Stl94LT1
It's for the "DIC" fuel mileage readings in the Y-bodies.
Therefore it does not get touched.
Correct?
Old Oct 8, 2008 | 02:55 PM
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Thats right.
Old Nov 16, 2008 | 09:03 PM
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Okay. Injectors are in and flow rate has been adjusted. However I am lean at WOT according to datamaster. Used to get WOT O2 readings in the mid 800's, now I am getting readings in the upper 700's.

Which way do I need to tweak the flow rate to richen or to get the readings closer to where they were? up or down?
Old Nov 16, 2008 | 09:15 PM
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Have you applied the blm locker yet? How is the fueling outside of wot.

If the fueling outside of wot is looking good. Adjust your wot % enrichment to fatten the whole wot fuel curve assuming it was pretty flat.

If the regular blms are showing mostly lean too tell the pcm the injectors are smaller and this will fatten wot as well.
Old Nov 17, 2008 | 08:14 AM
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Originally Posted by WS6T3RROR
Have you applied the blm locker yet? How is the fueling outside of wot.

If the fueling outside of wot is looking good. Adjust your wot % enrichment to fatten the whole wot fuel curve assuming it was pretty flat.

If the regular blms are showing mostly lean too tell the pcm the injectors are smaller and this will fatten wot as well.
Yes the BLM locker is applied.

Non WOT seems fine, the numbers are within bounds.

What is the exact name of the parameter for WOT % enrichment in tunercat? Would the number increase or decrease to fatten it?
Old Nov 17, 2008 | 12:41 PM
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Make the numbers bigger and it will be fatter. Its based on percentage. It adds with the rpm table to decide what air fuel ratio to provide.

pretty much its 14.7(1 - (coolant + rpm)) is how it calculates what to give you. Your trouble is going to be figuring out how much to add everywhere because narrow band o2's are not linear, I would think 1-1.5 would be a good start. Wont hurt anything going a little rich at first and leaning it out from there as needed. Usually 880-900 is pretty good for lt1's. Your dyno and your real world a/f wont correlate very well also dyno tunes are generally lean down the racetrack.
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