blown motor

[mansopoor]

i have a 97 4x4 blazer with a 4.3 vortec, i blown the motor as a result of a blown intake gasket, also discoverd the tranny is starting to slip, some people would say get rid of the truck but i have to much money put into the truck to stop now. the motor in need for this truck is so costly and hard to get where i live. i want to put an older style 4.3 with tranny in the turck cause there cheaper to get, but here is the thing, i have push button 4x4, and i dont know if the computer runs the tranny and the 4x4. if the computer dosnt run the tranny and the 4x4 i thought of putting in a tbi 4.3 with tranny, i dont know what to do at this point, i dont have the money to buy something eles, and i know what i have with the blazer (new brakes, rad, front end, tires, great body). if someone has some ideas for me and what i can do to swap out the motor and tranny and the problem im going to run into please let me know. thanks

[blazes9395]

To be honest with you, the only way to make this dependable and work properly in general is to replace the engine and/or tranny with a comparable part. The older engine/transmissions are not compatable with the wiring/engine computer etc. Although you can modify the truck to accept older engine transmission, in my opinion, you'll probably spend more money and tons of time trying to install older electronics in a newer truck. It will most likely be much easier and cost you alot less to find a good used engine and transmission combo and go that route. Or(this is what I would do and have done many times before) pull your engine and tranmission and rebuild them yourself. Either way, if you have questions, ask away!

[mansopoor]

i have a person down here that has a 4.3 and it in a 96 astro van, i asked him if its got TBI or spyder injection and he didnt know, from i what i know, if its a 96 then it would have to be spyder injection, but i could be wrong, would you be able to tell me if a 96 comes any other way then spyder injection. thanks

[old_master]

The 4.3L 1996 Astro was CMFI.

[mansopoor]

what is CMFI and is it the same as in my blazer. thanks

[old_master]

Central Multiport Fuel Injection (CMFI) has a single injector with the "spider" to distribute the fuel to each intake port. Throttle Body Injection (TBI) has two injectors in a "carburetor-like" housing. Central Sequential Fuel Injection (CSFI) has 6 mini injectors in one housing under the plenum and fuel is distributed through a "spider" to each intake port. I'm not certain which system you have on your 97 (CMFI or CSFI) but there is a GM technical service bulletin that involves modifying CSFI to CMFI, so it CAN be done. The TSB # is: 00-06-04-003B.

[blazee]

The 4.3 engines with the vin "w" single central maxi injector (most commonly known as "CPI") ended in 1995. All the 1996+ VIN "W" have the CSFI injection which consists of six centrally located injectors, that activate sequentially, sending fuel through the spider before being injected into each cylinder through spring loaded poppet valves. The Astros and Blazers have the same CSFI injection, they are the "L35" Vortec 4300.

TSB 00-06-04-003b covers replacing the CSFI with the new MFI system. The new MFI system is not like the old CPI. The MFI resolves the problems associated with the CSFI's poppet valves. The poppet valves are eliminated and 6 mini injectors are moved to the end of the fuel lines to take their place. All the wiring and sequential firing order is the same so no upgrades to the vehicle harness or computer are necessary.