99ranger misfire #4 need help

[ExplorerDMB]

So your saying there wasn't a lot of carbon build up? That is odd, you said you did a compression test on #4 correct? what about a leakdown test

-Drew

 

[fat freddy]

how do i do that and what will need

 

[ExplorerDMB]

a leakdown test is basically a gauge that hooks up to the spark plug hole (just like a compression check), but you put compressed air into the system and see if any of the valves are open, rings warn, or worst of all - holes through pistons. With you saying that #4 had no sign of carbon build up, confirms that you have a misfire there.

-Drew

here is the one we have a work (atleast looks like it)

 

[fat freddy]

I had the compression checked again after running it awhile
the#4 had 95 the others around 120 the man said the rings
was not the problem it was the valves on that cylender
maybe burnt or not seating what do you think

fat freddy
99 ranger 3.0
flex fuel

 

[ExplorerDMB]

The leakdown test will tell you for sure. Usually you go with your highest compression cylinder and compare that with your lowest. If it is around 30 or less...there is an issue (mechanically). I would look into possibly pulling the head off or doing the leakdown test. The leakdown test is easy to do...make sure its at TDC on the compression stroke (both valves closed) and then listen at your Throttle body (with the butterfly open), your oil filler cap (with the cap off), and at your exhaust tip. You will have to listen hard but if you hear a hissing, that is where your problem is. Intake/Throttle Body, Exhaust/Exhaust Tip, Rings/Hole in piston/Oil Filler

Hope that helps

-Drew