1991 C1500 TURBO 5.3/4L80E

[RDF1]

Thanks! Glad your enjoying it.

I did alot of reading and bunch of guys were using a fbody throttle cable so I found one on amazon for cheap.
Get it in and nothing fits... so I made do.

Made an adjustable bracket to figure out how it needs to be.

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[gnrl]

Cool build! For the computer, are you doing the tune or having it done? I have the equipment to flash 512k and 1M PCMs, but had to rely on people for help to make the actual binaries.

 

[RDF1]

I'm using EFI Live and doing it all myself. Attempted the COS 5 but going back to COS 3.



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[RDF1]

Borrowed some stock 25# injectors from a buddy and flashed in stock injector data. It fired up and ran great. Then started sputtering and died. Checked everything I could think of. Then it dawned on me that I only put a few gallons of gas in the tank. It was empty. Put 5 gallons in it and never could get the pressure up. Most I seen was 25psi. Turned on 2nd pump (dual walbro 255s) and still nothing.
Spun the filter off and got a lot of air.

Took the Schrader valve out of the fuel rail and ran a hose back to the filler neck.. ran it for a few minutes and had horrible flow.

Going to find another filter tomorrow and see what happens.

But did manage to put the air filter on....

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[Christian Steffen]

I'm using EFI Live and doing it all myself. Attempted the COS 5 but going back to COS 3.



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What's the difference between OS 5 and 3? Just kinda curious. I assume you're going to run speed density?

 

[RDF1]

What's the difference between OS 5 and 3? Just kinda curious. I assume you're going to run speed density?

Yep Open Loop Speed Density.
I took all the wires out of the harness for the MAF and all the oxygen sensors.
All i run is the IAT sensor and wideband.

COS5 has TPS VE table for Throttle position fueling option, Additional timing and fuel modifiers for nitrous and such.
I wanted to use the COS5 incase i need to manually pull some timing, for bad gas or something weird like that. I like options.
Or if i just wanted to spray a small shot of nitrous to help spool the turbo i can adjust the timing and fuel for that.

 

[Christian Steffen]

Yep Open Loop Speed Density.
I took all the wires out of the harness for the MAF and all the oxygen sensors.
All i run is the IAT sensor and wideband.

COS5 has TPS VE table for Throttle position fueling option, Additional timing and fuel modifiers for nitrous and such.
I wanted to use the COS5 incase i need to manually pull some timing, for bad gas or something weird like that. I like options.
Or if i just wanted to spray a small shot of nitrous to help spool the turbo i can adjust the timing and fuel for that.

That'll keep it nice and easy.

I understand wanting to have all the options possible too.

EFILive has some nice custom OS options, as far as I know there isn't anything in the HP tuners custom OS specifically for nitrous, though there are way to accomplish the timing reduction. The only cool custom thing HPT has is the real time tuning option, not sure if EFILive has anything like that built in.

 

[RDF1]

Yea i do like EFI alot better than HPT. But each has their own good and bad things.
Ive got HPT from a buddy to tune his Twin turbo 5.3 in a old Nova and dont like how anything is laid out in the scanner or editor.

You can go to the scan tool and manually add or subtract timing and such with EFI, build a map so you get your final timing and use that to adjust the timing table in the tune.
HPT just has a cool name for it, it doesnt adjust the tune but you can use the BI-DI controls to manipulate the tune.

Ive thought about the IAT resistor trick too tho. I doubt ill ever see -40* down here...

 

[Christian Steffen]

Yea i do like EFI alot better than HPT. But each has their own good and bad things.
Ive got HPT from a buddy to tune his Twin turbo 5.3 in a old Nova and dont like how anything is laid out in the scanner or editor.

You can go to the scan tool and manually add or subtract timing and such with EFI, build a map so you get your final timing and use that to adjust the timing table in the tune.
HPT just has a cool name for it, it doesnt adjust the tune but you can use the BI-DI controls to manipulate the tune.

Ive thought about the IAT resistor trick too tho. I doubt ill ever see -40* down here...

Yeah its kinda nice being able to edit the table values, but ultimately the same can be done without the tables being loaded into the scanner.

And yeah I think the IAT table would be the best way to pull timing for nitrous if there isn't a provision in the tune. If you ever do see -40* down there, I think how your truck runs will be the least of our worries. haha

 

[RDF1]

Woops.. IAT table only goes down to 14*. Ill try it both ways and see what happens.