8.1L injector values

[sinr98]

Hey guys I have an issue I was hoping someone can help me with. I am doing a cam swap in my 04 Silverado SS, and I have some 8.1L truck injectors GM part # 12574927. They are brand new. I was looking for the stock injector values in Holden crazy and found 3 different vehicles from the years that these injectors work on, but all 3 values from the stock tune are different. One is an 03 Avalanche, one is a 02 Silverado 2500, and one is a 04 Sierra. All have the 8.1L engines but with different OS. When I cross referenced the injectors they said that they will fit 02-06 vehicles. I already swapped the values from the 04 Sierra in my current tune, but when I looked at the other 2 tunes they are quite different and I want to make sure that I get the right values. I know I might have to play with the values but I would like to be close to begin with. If anyone can help me out on this I would really appreciate it.
Thank you

[Steve Bryant]

sinr98,
The injectors will fit all of the year models you mentioned as far as I know. I am running them myself on my 2000 Yukon XL (6.0L K2500 4X4) which has a return (constant fuel pressure system) with the IFR shown in the attachment.

I'm pretty sure that your truck has a returnless fuel system and the rate will not be a straight line, but will vary according to MAP. Pull one of those tunes out of HoldenCrazy.com.

What OS does your truck have? I'll be glad to give you some more help.

Steve

[sinr98]

Here are my files. Yes my truck has a returnless fuel system. Thanks for your help. I did use a 04 Sierra 8.1l for the injector values.

[Steve Bryant]

sinr98,
It looks like you're running stoic at most throttle positions/RPMs but I can't tell what it's doing at WOT without a WB. It looks like you're doing pretty well overall.

Give me a shout if you want to talk things over some more.

Steve

[joecar]

Unrelated: set D0961, D0962 to 100% to avoid strange shift table conflicts.

[sinr98]

What will setting the D0961 and the D0962 do exactally? And should I set Normal, Performance, and Cruise all to 100? I wouldn't mind my tow haul mode to be a performance mode if it can be. Thank you for the help. I appreciate all the help everyone has given me.

[joecar]

See here: showthread.php?t=3336

[sinr98]

Joecar. I honestly am just starting out on tuning, and that file is my first tune I have ever done. As for the trans tuning, I know even less on that than I know about the engine tuning. In the thread you posted it seems like you were telling the OP that his up and down shifts and pt shifts were not jiving. Is that what you saw on mine? I was going to try and make a excel file to do what you did with his settings to see what mine looked like that way but I haven't had the chance. I thought I had 50% tm taken out of the trans but I can't find that I did. I would like to get my tune close now since I will be putting a cam, headers, and a TB stall in it in the next few months. I just don't want to blow or mess anything up. I really appreciate the info. I just hope I can gather half as much info that others have. Thanks again.

[joecar]

sinr98,

I'm saying that your part throttle shifts may be occurring at different points than what is specified by the PT upshift tables D0901, D0902, D0903 and PT downshift tables D0906, D0907, D0908...

[ enter those table id's in uppercase in the Search box in the tunetool, that will take you right to the table ]

Most people don't notice... but some people run into this when they try to change the PT shift tables, they find that it doesn't shift at the points specified by the tables... or maybe that a large throttle downshift fails to occur.

this happens mainly because the kickdown ("downshift") tables dip down into the upshift portion of the PT upshift table... that is the shaded area shown in that other thread... the PCM is placed in a situation where two tables are specifying conflicting shift commands... either of the two tables may win (not necessarily the kickdown table)... this leaves the tuner wondering why the PT shift table is not being followed, or only being followed sometimes.

[ the throttle kickdown table is another form of PT downshift table... but it was supposed to be intended to be used at 100% throttle as the name of it implies ]