OBD II LT1 Engine Swap Gotchas???

[Roger Heflin]

On Tue, 2 Feb 1999, Joe Gervais wrote:

> I've been quiet on this list for a while. I swapped a 93 LT1 into my early
> Corvette, and thanks to this list and others, have enjoyed that swap and am
> about to do a similar swap into a 69 Camaro with a 97 Z28 motor that I couldn't
> pass up.
> 
> I know some of the high horsepower guys I know have swapped from OBD II to OBD
> I PCMs due to difficulties of squeezing 600 HP out of an OBD II controlled
> motor. For a stock, smog exempt OBD II swap, are there any pitfalls that I
> should look out for? Anyone else on the list already done such a swap?
> 
> Joe
> 

If you are swapping in the standard stock unmodified engine you will
only need to fake out the sensors that you aren't using, such as the
additional O2 sensors behind the cats.  Also I believe there are some
things that detect a loose gas cap, this will need to be faked out
also, and probably several other sensors of the same sort.   That is I
believe why they generally put a 95 pcm in, they don't have to worry
about it.   The 96 + pcm does have some nice features, it will count
misfires, but this is supposed to get rather confused if you put a cam
that is too big in the car, and count alot of misfires and set SES
lights and such.   

If the engine is being modified then the misfire detection seems to be
the most troublesome thing, if you are staying in the same car.

There are supposed to be "O2" sensors to properly fake out the behind
the cat sensors inputs so the computer does not notice.  I think it
takes the front O2 sensor and makes up the rear signal based on that.

And I guess the other problem is not many companies know how to
program the 96+ cars, so that is really a problem.

			Roger