Expert: Mike Evans - 5/2/2010

Question
I bought a 99 Sonoma for my son with engine issues to tinker with...It has the 4.3 vortec "x" engine code in the vin...can i replace with a 4.3 vortec "w" engine without too much trouble ? from what i ahve read they are identical other than the "w" has 10 more horsepower.thanks in advance

Answer
    There are a lot of little differences between these engines.  But, none of them are truly important.  What you WILL have to do is get the computer reflashed to work with the engine you choose.  This is not a big deal and costs a couple of hundred dollars.  If you can find a mechanic who has invested in the equipment needed to do the programming himself, it would be better.  The computer needs to know the correct axle ratio, tire size, etc.  It would be a lot simpler for you if you could get the same type of engine from the same year vehicle, then no reflashing would be needed and it would just be a mechanical project instead of an adventure in programming.  Of course, taking the time to learn this programming procedure might be fun for you.