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HPtuners Longshot

454Sub

454Sub

5/8 ton status
Joined
Apr 11, 2012
Posts
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Location
Southern Illinois
Does anyone happen to have or even know factory 8.1 truck injector pulse width numbers? And the minimum width.

I'm using it to do a hodge podge of a 5.3 build. Right now it runs decent ish with the KPA injector table set to 29.9 across the board. But technically an 8.1 injector I believe pushes 35-38lbs at 58 psi. So knowing these numbers are obviously not correct and my VE table being strange has led me to believe that it's my injectors and their info that is not jiving with what I currently am running.

Anybody know of anyone who would happen to of opened a factory 8.1 03- truck and would have the injector data?
 
454Sub said:
Does anyone happen to have or even know factory 8.1 truck injector pulse width numbers? And the minimum width.

I'm using it to do a hodge podge of a 5.3 build. Right now it runs decent ish with the KPA injector table set to 29.9 across the board. But technically an 8.1 injector I believe pushes 35-38lbs at 58 psi. So knowing these numbers are obviously not correct and my VE table being strange has led me to believe that it's my injectors and their info that is not jiving with what I currently am running.

Anybody know of anyone who would happen to of opened a factory 8.1 03- truck and would have the injector data?
Click to expand...

Are you returnless on the 5.3? The HP tuner forum has a few 8.1 tunes but you need to get the right numbers for the style of fuel system you are using. Systems with vacuum referenced regulators use a constant number (30 across the table w/8.1 injectors) where returnless systems will vary around 10% from one end of the table to the other.
 
It is return, and I set it to 29.9.


I guess I need to research it more.

It fires up and runs good from an all night sitting, but it stumbles on the initial tip in, once it's wound up it's fine.
 
454Sub said:
It is return, and I set it to 29.9.


I guess I need to research it more.

It fires up and runs good from an all night sitting, but it stumbles on the initial tip in, once it's wound up it's fine.
Click to expand...

What do your fuel trims look like? What air box/intake tube/MAF are you using? If you want to post a couple of pictures of your setup and some data logs I can help you sort this out.
 
Yeah, I don’t have fuel injector data but my Burb had the same stumble after the engine swap where I did a fuel trim reset and it clear it right up. I used a GM Tech II to do the reset but I had to call it a 6.0L as it the tech II didn’t give me an option to a fuel trim reset on an 8.1L. It is crazy as the engine smoothened right out the minute the trim reset was complete and the tip-in bleep was gone.

There is a VIN in the Resource Thread for a 2001 3500-HD that would have return type fuel system. Maybe someone can pull data from that VIN
 
bigblock72 said:
The HP tuner forum has a few 8.1 tunes but you need to get the right numbers for the style of fuel system you are using. Systems with vacuum referenced regulators use a constant number (30 across the table w/8.1 injectors)
Click to expand...

I'm also looking for this info. Does 30 across the table apply only to 8.1 injectors? Would it change if the engine is a 6.0, 5.3, or 4.8?
Thanks
 
Lol. Ironically I remembered I actually have all the 8.1 data.


And the IFR table is set to 29.9 across the board, but the differences go into the actual pulse and duration of it and so on. I updated it, and it runs smooth now. I'm getting it as close as I can until the wideband shows up to finish it.
 
454Sub said:
Lol. Ironically I remembered I actually have all the 8.1 data.


And the IFR table is set to 29.9 across the board, but the differences go into the actual pulse and duration of it and so on. I updated it, and it runs smooth now. I'm getting it as close as I can until the wideband shows up to finish it.
Click to expand...


What is wideband?
 
Narrow band is what the LS PCM uses to read the exhaust. Basically it's sort of accurate real close in either direction of 14.7:1 but not very accurate at all as it swings one way or the other.

Wideband is accurate all the time, and is the only "correct" way of tuning. I just don't have one on hand, so I'm guesstimating my way through it with a vac gauge, and how it smells on startip and so on. Making very small changes. I will get one for it here soon but want to do some part throttle tuning for now.
 
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