K1500 5.7 Tuning Help

Looking for a little guidance on my truck that I've been restoring and driving over the past couple of years. Truck is a 1998 K1500 with the 350 and it has the updated spider injector assembly (Believe it's SPFI, forget the acronym). It's driveability is just okay and I'm looking to improve it after rebuilding most of the drivetrain.

Basics of what I have - engine is rebuilt but still stock bore, cam is 1 bump up (Comp cams), upgraded spider injector, running stock exhaust manifolds into a Flowmaster exhaust system with O2 sensors still installed/operational, transmission is new from Monster (Was told it's a 4L65 now), 14 bolt rear end rebuilt with new tubes and original gears, stock black box computer.

It was tuned recently but I do not like how it was done and I'm looking for other options (Didn't care for how much it cost to what was done and to "Undo it" will cost me more so back to square one). Biggest issue I have is how the shift points were changed making back road driving a little annoying as well as loss of MPG's, 4th gear now does not come into play until 46 MPH. I forget what the original shift points were.

Is it worth making the swap to the 0411 ECM and going through the process of re-pinning everything using LexTech's information and tuning or stick with the black box ECM? Or go the Blackbear tune route? Or find a local tuner but so far that's not proving to be easy. I'm local to MJE Engineering but I have been unsuccessful in getting him on the phone or any email response. This truck is a driver and I enjoy driving it regularly during the warmer months so I'm not looking for anything crazy. Just want to get better mileage (Used to get 18 MPG on the highway) and improved shifts since it takes more gas than I recall to get going from a stop. My guess is this is likely the cause for the lower mileage.

Looking for suggestions on this to help improve the driveability since I enjoy driving this truck more than any other vehicle I've ever owned. Thanks in advance!

98SilveradoK1500 said:

transmission is new from Monster (Was told it's a 4L65 now)

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98SilveradoK1500 said:

Biggest issue I have is how the shift points were changed making back road driving a little annoying as well as loss of MPG's

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So... it's a 4L62.8?

98SilveradoK1500 said:

Believe it's SPFI, forget the acronym

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MPFI

98SilveradoK1500 said:

Or go the Blackbear tune route? Or find a local tuner

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Having heard several other members go the mail-order tune route, I'd go with a local tuner, but I have Able Racing nearby, so I understand that dudes living in Moose Butt, Wyomazona can't. If you're not out in the sticks, ask your friends and co-workers, there's likely several tuners. Hit up the local drag strip on test-n-tune night and ask around.

Yes, a 4L60E variant! It has driven fine for me but it definitely needs some tweaking/tuning. It'll move anything you put in the bed or tow but getting up to speed seems slower than I remember before rebuilding everything. I can check the paperwork later to see exactly what the trans is.

Thank you, MPFI, that's it. Paperwork at home for that as well.

I have a couple of places I've reached out to and it's either we do not work on these or no response. The place I mentioned originally states they specialize in these which is why I was hoping to get in touch with them but that has proven unsuccessful.

Does anyone in the New England or MA area have any input for places that do tuning?

I would repin for the 0411. A dongle and free software and you can tune it yourself. Probably under$100 in tuning stuff. You care more about how it runs than any tuner will so that's the rout i would go. It will take a little time but there are guys here that will help walk you through it and you will end up with a better running truck than any local tuner more than likely and surely better than a mail order tune

I doubt it will want to lug along in 4th under 45 mph and it is very abusive on the transmission to force it into overdrive and lockup much below 50 anyway.