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1989 Chevy K2500 TBI Setup - What's Your Problem?

Here's where it gets tricky. The GM TBI is a speed-density system, which assumes the engine ingests a given amount of air at wide-open throttle (WOT). Mass airflow systems measure the air entering the engine, but speed density systems like those used on these TBI engines do not. Instead, they assume a stock airflow value based on throttle position and manifold absolute pressure (MAP) sensor readings. The fuel requirements at part- and full-throttle are established by the factory based on the engine's air and fuel demands. Increasing airflow with a better intake, heads, camshaft, and/or exhaust increases the airflow through the engine and demands a change to the stock computer base fuel and spark maps. These TBI injection systems are controlled by GM computers equipped with chips that are burned or electronically imprinted with the necessary information. Later GM computers use erasable EE-PROMS that can easily be reprogrammed while still in the vehicle. However, the chips in the TBI trucks and cars have to be removed and a new chip is burned with the new information. This can get time consuming and pricey if you have to make multiple changes to improve driveability. If you plan to do this, call one of the companies such as JET or CFM Technologies to find out about a complete package it offers. These companies can supply the parts and a compatible chip as a package that has a much better chance to be correct on the first try. These systems cost a little more than what you could put together on your own, but that's because you're paying for their experience and tuning expertise. Trust us, it's worth the investment.

More Info
Airaid Filters
Phoenix, AZ
888/876-8984
airaid.com

CFM Technologies
Moultonboro, NH
603/238-6721
cfm-tech.com

Edelbrock
Torrance, CA
310/781-2222
edelbrock.com

Hypertech
Barlett, TN
901/382-8888
hypertech-inc.com

JET Performance Products
Huntington Beach, CA
800/535-1161
jetchip.com

Scoggin-Dickey Parts Center
Lubbock, TX
800/456-0211
sdparts.com

Summit Racing
Akron, OH
800/230-3030
summitracing.com

Trans-Dapt
Whittier, CA
562/921-0404
tdperformance.com

Turbo City
Orange, CA
714/639-4933
turbocity.com

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