Question i want to replace the engine(4.3 liter) to a 350 engine in an 1989 gmc 1/2 ton 4x4,what kinds of problems will i have with the computer system. I was told that all I need to do is replace the chip is this true ,and where exactly is the computer on my truck.Both engines are TBI .
AnswerWhoever told you that ALL YOU HAD TO DO WAS REPLACE THE CHIP IS 100% incorrect.
Here are only a FEW problems you are going to run into.
(1) The ECM'S (computers) for a v-6 and v-8 are DIFFERENT.
(2) All of the electrical harnesses for a v-6 and v-8 are
DIFFERENT.
(3) The exhaust systems are DIFFERENT.
(4) If your state has mandated EMISSIONS INSPECTIONS your
conversion will NOT pass as they will program the
emissions settings according to the 8th digit of your
vehicles VIN # of which will be for the v-6 engine.
Back in the early 1970's and backwards BEFORE computerization came to be, You could swap from a v-6 to a v-8 without to much hassle, But with the introduction of computers in the late 70's your in for a VERY COSTLY and time consuming REGRETFUL event trying this swap.
Yes, I know, The electrical connectors at the computers LOOK THE SAME. Your RIGHT, They LOOK THE SAME, But the individual wires are located in different areas of the connectors. As an example lets say that your BLACK plug has a green wire in slot A1 for your v-6 engine. For the v-8 engine slot A1 may have a yellow wire and this holds true for each and every wire in each and every electrical connector.
I can't make this decision for you but I have done 2 and ONLY 2 of this type of conversion and I have over 20 years of expertise and would never do it again. It is just not worth the vast amount of MONEY, TIME and DIFFICULTY.
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