In an effort to thwart the VATS system on my recently transplanted 92 Firebird TPI (going into a Wrangler), I have ordered a non-VATS programmed PROM from Painless Wiring. Unfortunately, I am running into conflicting data in terms of part number charts for them. What I ordered is, according to some parts lists, a 92 350 TPI PROM instead of the 92 305 TPI PROM. Can anyone tell me if it will still work or not prior to me wasting my time installing/ testing/ blowing the damn thing up?

I'm really hoping there's no real difference, and if there is, that it would be an improvement, but the way things have been working, I DOUBT I'll get THAT lucky!

Thanks in advance!

Matt

------------------
90 Wrangler with Firebird Formula TPI 305, Chevy granny low 4 speed tranny and Scout Dana44 axles.

 

There are many many differences between these two chips. Most of the differences are the following:

Fuel cutoff and resume speeds higher on 350
Injector flow rate and cylinder volume constants are higher on 350
EGR off (%TPS) higher on 350
TCC lock and unlock constants are higher on 350
Warm 02 Closed loop delay timer higher on 305
Cold 02 Closed loop delay timer higher on 350
Min Cool for closed loop fuel higher on 350
Min Cool for WOT AFR higher on 305
Main spark advance tables are very different. 305 tables have more spark advance because the 305 heads take longer to propogate the flame.
Start up spark advance higher on 305 for same reasons as above
Closed TPS spark advance higher on 305 for > 2000 RPMS for same reasons as above
WOT spark advance higher on 305 for same reasons as above
Maximum knock retard vs. RPM in WOT is more for the 305
Volumetric efficiency tables (fueling) are very different. 305 tables use less fuel except when > 4800 RPMs.
TPS threshhold for WOT is greater on 305 (more pedal travel on 305 to reach WOT)
TPS threshhold for WOT (high coolant) is greater on 305
WOT change to AFR vs. coolant greater on 350
WOT change to AFR vs RPM greater on 350 except when > 4800 RPMs.
Pump shot tables are relatively different (more for greater TPS for 305)
Targer idle RPMS different across the board
Open loop change to AFR vs. coolant greater for 305 except at very low temps (-28ceg C)
Open loop change to AFR vs. MAP is greater for 350
Choke vs. Coolant is different across the board
Injector pulse width correction vs. battery voltage is different across the board
TCC lock and unlock tables (all of them) are different across the board. Generally speaking - less throttle unlocks the TC for the 305.

There are more but I'm stoppping here. You get the gist. Go with the correct chip.

 

WOW... there are quite a few differences then.... I guess since I do not really care about getting every last horsey out of it, would it still allow it to run? I mean, I don't race it (I built this Jeep with a Chevy truck transmission that has a 6.55:1 first gear, 2:1 gear reduction in low range and will have 4.27 gears at the diffs, so peak horsepower isn't really as much of an issue as running/not running is. Currently it's NOT running, and I just want to change that status.

Thanks for your quick response!
Matt

------------------
90 Wrangler with Firebird Formula TPI 305, Chevy granny low 4 speed tranny and Scout Dana44 axles.