Howdy!

[justatech]

Hey there! Thanks for adding me to the forum. I am fixing up a 93 Chevy k2500 with a 5.7 TBI. I am getting it pretty close to good but it hasn't run right since the PO swapped in a crate motor and put headers on the truck. They also seem to have deleted the EGR and there is no cat. I'm thinking that the lack of the post cat o2 sensor and EGR are contributing to this so I'm looking at getting a chip burner and modifying the tune to get thus thing running right. Looking forward to learning from you all!

[steveo]

assuming you still have the original ECM for the truck?

a 1993 engine like that shouldn't have ever had a post cat o2 sensor so that's nothing to do with it

the lack of an EGR could cause a bit of pinging in the mid cruising range, basically when it 'thinks' the egr is active it adds timing advance

that thing is speed density so really you need to create a new VE table to match the VE of the crate motor and it's peripherals (intake and exhaust)

[justatech]

The truck does still have the original ECM. I'm glad to hear that the EGR and O2 shouldn't be an issue. Thanks for steering me in the right direction. I should be getting the cables and parts I need to tune it in the next week or so and I am happy to have some direction on getting this thing dialed.

[steveo]

with a speed density ecm you have a map that describes load vs rpm vs airflow for your particular engine

that changes when anything regarding airflow changes

that's definitely the first thing to tune