Sorry, a few more tbi swap questions...

[ugly_blazer]

I will be swapping an 89 tbi into my K20. I am going soon to get new exhaust, and the truck already has new headers. The exhaust shop has the boss to weld to the collector for the O2 sensor. Is the placement of the sensor critical? Also, my donor engine has a 1 wire sensor in the exhaust manifold. It has been brought to my attention that I will need a 3 wire sensor. Does anyone know what vehicle I should have the parts store look up so I can get a 3 wire sensor?

 

[dyeager535]

You would want the boss as close to where the tubes come together as possible.

Mine is actually in the exhaust pipe, not the header, as I didn't want to screw up the coating anymore than necessary.

It doesn't appear that I will need the 3 wire O2 sensor, as I go closed loop no problem, and seem to stay there. I've still got a lot of tuning to do, so I can't say that the O2 situation is ideal, just that it works now.

My headers are coated on the outside, and I can say without a doubt that coating makes a HUGE difference in the amount of heat shed or contained. This may be the reason some people "need" the 3 wire sensors with headers and some do not. Coated inside would probably be the best header to have in this situation, but a 3 wire sensor is probably more cost effective. Plain steel headers will shed more heat before the sensor, so that is something to consider as well.

In any case, I'd try it with the 1 wire first, and watch it with a scanner. If it goes closed loop and stays, I'd leave it as is. Running a 195* t-stat can't hurt either.

 

[ugly_blazer]

I guess I could always try the 1 wire that I have and see if it works. I bought the non-coated cheap $87.00 headers /forums/images/graemlins/crazy.gif