basicly what it says.what realist gains on burning a chip on a stock 305 TBI?gas milage,horse power,and torque gains.I am wanting to look into this because in the future I will upgraiding to a 350 soon.

 

Well on my 350 TBI truck that I tuned it was like 2 MPG, 15 FWHP, 20 ft/lbs of torque, over a baseline that included headers, full 3" dual exhaust, Ultimate TBI mods, and a L69 dual snorkel air cleaner. I converted my truck to a 9C1 TBI 350 with the TBI setup from the Caprice. My numbers are over the HO 350 tune from the 9C1. Similar gains would be expected from a 305.

I love my truck but, my TBI van will blow its doors off .

 

is there a highway mode in the prom?

 

In the 8746 caprice ECM I am using in that truck there is. You have to remember that my 1980 C10 has a 3.08 gear, 3 spd column shift transmisson (NO OD), and weighs 4,000+ lbs. It regularly gets 22 MPG with a 350 TBI and NO OD. The engine is turning about 2,200 RPM at 60 and about 2,500 @ 70. The load on the 350 engine is pretty low at that speed and the engine tolerates leaner mixtures and more timing easier than my 305 van does running at 1,800 and 2,100 respectfully. The truck uses the highway mode alot more than the van.

Carbed the truck would get 15 MPG with a Dual Jet on it (Front half of a Quadrajet and had crap for HP), with the TBI conversion it would get 20 MPG, a custom tune for the truck brough it to the 22 MPG highway. Pretty good for a truck with NO OD if you ask me. I found over 40 RWHP with the tuned TBI vs. the same carbed 350 when it originally went in.

 

It varies so much that it'd be difficult to even guess what gains you might see.

What you can do, it get rid of that *too high* cold idle, and make the car smoother to drive. MPG well that's got alot to do with driving style. Once you get the car running nicer, it's all to easy to use WOT much more, and that's a MPG killer..

 

Yep, especially that cold start flare on TBI due to the IAC park position. You didn't say if it was an automatic or standard but if auto you can change torque converter lockup/unlock points, tps, etc. If it is a standard you can delay the pesky upshift light.

Last time I heard, Grumpy does not use highway mode, but rather runs his engine a little rich with less timing and still gets relatively good mileage. His is not naturally aspirated though, think 80s GM muscle car with a Turbo V6.

You can also change when you car goes into Power Enrichment mode. I typically run lower % TPS at lower engine speeds than factory. The engine responds better and pulls smoother from a stop, then once you get to cruising speed it is back out of PE mode due to the higher RPMs.

My timing just dumps as the MAP decreases to keep my 10.3:1 iron headed 305 from pinging itself to-death.