Instrument Cluster...and an interesting observation
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Senior Member
Joined: May 2004
Posts: 577
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From: Longmont, CO
Instrument Cluster...and an interesting observation
I have a 98' Expy with a 5.4 literthat I'm going to change the non P.I. heads out to the 99' and up P.I. ones. I know the computer is gonna need tweaking, so instead of getting a program burnt, and since I really hate the 98' instrument cluster....could I use a 99' and up engine/tranny wiring harness, computer, instrument cluster, and that wiring harness without changing all the wiring, e.g. the power windows, sunroof, etc. I'm under the impression that the computer and its wiring harness only deals with the engine, tranny, and instrument cluster, and has nothing to do with the other interior features. Am I right, has anyone ever done the instrument cluster change?
My observation: I recently drove an 02 Expy and my buddy's 02 FX4, both with the 5.4 liter. The FX4 has dual exhaust, cold air intake with K/N filter, while the 02 Expy was bone stock. The Expy has more pep off line than the FX4!!!! The Expy has 3.73 gears and a 4R100 tranny, while the FX4 has 3.55 gears and a 4R70W trans. I realize rear gearing helps the Expy out, but it is heavier than the truck, and the truck has all these bolt on mods but is a tad slower than the Expy off the line? What gives? Is it the tranny gearing? To further test this out, I drove my other buddy's truck, a bone stock 99 F150 with a 5.4 and 4R70W with a non posi 3.55 rear. It too isn't as peppy as the Expy. I went one extra step and actually raced my buddy's in an abandoned parking lot (what a site, 2 Expy's and 2 F150's duking it out, hahaha) and the 02 Expy got all of us off the line, and as a matter of fact, my 98 with non P.I. heads, 3.73 posi rear, 4R100 tranny, kept up with the trucks, but the 02 Expy got all of us off the line, the FX4 eventually pulled away from us. Does anybody know why this is? Any input on either of these subjects is greatly appreciated!!
My observation: I recently drove an 02 Expy and my buddy's 02 FX4, both with the 5.4 liter. The FX4 has dual exhaust, cold air intake with K/N filter, while the 02 Expy was bone stock. The Expy has more pep off line than the FX4!!!! The Expy has 3.73 gears and a 4R100 tranny, while the FX4 has 3.55 gears and a 4R70W trans. I realize rear gearing helps the Expy out, but it is heavier than the truck, and the truck has all these bolt on mods but is a tad slower than the Expy off the line? What gives? Is it the tranny gearing? To further test this out, I drove my other buddy's truck, a bone stock 99 F150 with a 5.4 and 4R70W with a non posi 3.55 rear. It too isn't as peppy as the Expy. I went one extra step and actually raced my buddy's in an abandoned parking lot (what a site, 2 Expy's and 2 F150's duking it out, hahaha) and the 02 Expy got all of us off the line, and as a matter of fact, my 98 with non P.I. heads, 3.73 posi rear, 4R100 tranny, kept up with the trucks, but the 02 Expy got all of us off the line, the FX4 eventually pulled away from us. Does anybody know why this is? Any input on either of these subjects is greatly appreciated!!
Thread Starter
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Senior Member
Joined: May 2004
Posts: 577
Likes: 1
From: Longmont, CO
Can someone please respond........hehe I would like to start this project soon, and just want some feed back to see if this is a do able project, maybe some insite into what I'm getting myself into...I'll do it alone, but thought someone may have tried this before............again this site is really helpful, I'm hoping it can help me again!!
Technical Article Contributor
Joined: Dec 1997
Posts: 9,417
Likes: 11
From: Windsor,Ontario,Canada
You will have to deal with 10.5:1 compression ratio created by this swap. Using a new computer will not cure this. The Pi engines use a different piston that has a deeper dish to lower the CR back to there it was. So both PCMs most likely have simular calibrations. Your best bet is to talk to mike Troyer over in the Chips section about burning a chip for the new heads.
Regards
Jean Marc Chartier
Regards
Jean Marc Chartier