engine compression test for backfire

[nothinbutroad]

my 1991 explorer has been backfiring, so on the advice and the good people on here i did a compession test, the results are as follows
c1=130
c2=130
c3=145
c4=150
c5=140
c6=140
20psi difference between high and low and i didnt see the needle lose pressure so i dont think i have a leak, is that acceptable?

also the neighbor seen me workin on my truck and took a look, he said the map sensor should have a hose on the nipple, the old 1 didnt have a hose on it, and everything i looked up online shows no hose attached to it, just the wiring. should it have a vacuum line or just be open like i have had it?

 

[arco777]

There would only be a hose on the MAP sensor if it was a Speed Density setup. The Explorer is Mass Air so no hose required - reference is atmosphere.

Sounds like your compression numbers are fine.