im helping my friend do his b20 swap in a 91 ls there is two sensors beside the oil filter one has a green plug the other has a rubber boot ( not the oil sending switch) what r these sensors also where do they go on the b20
i think the one with the green plug is the thermostat cooling switch


please help im in the middle of the swap right now that is all we have to do before putting it in please hel

 

green plug is knock sensor and the other with boot is coolant temp. switch

 

(which is used to turn on the radiator fan)

 

The green plug is NOT a knock sensor. It's a oil pressure driven switch that works in conjunction with the speed sensiitive power steering that the 90-93 'tegs use. I've never hooked it up, never throws a code or causes a problem, just ignore it.

 

then there should be three plugs back there. right ?

 

Right, you should have these:

A 1 prong oil pressure sensor
A 2 two prong coolant temp sensor
A Green plug for the other thing(don't worry about this one)