Thanks again for help everyone .
No white smoke . No coolant leak, coolant level is fine and has been for long time .Oil as well. He said he took the coil out of 5 put it in another and it didn't give off any message. SO he tested that he said . The Psi reading was done 2 times and each time it showed compression loss .2nd time he said was lower or worse. Other was all fine . That has been good while since it was done . 1 thing I noticed I forgot to mention at times the engine light goes off. Soemtimes a day. Sometimes for 30 seconds but comes back on and stays on .
And blinks when acting up . The jeep runs very good normal when not doing this . I will get other stuff asked when possible . Looks like I might need a second opinion they may be missing something .Never had a issue with scam me .But something seems off as you guys said because we are driving it fine. Only car we have and have very ill family member . So thank you for all help .
That's hardly a conclusive test of the ignition coil; what if when moved to another cylinder just happens to be one of the times that it "self-corrects" for a bit.. you'd learn nothing. There are specific tests with a multi-meter that can and should be done with an ignition coil, primarily testing resistance across the primary and secondary windings.
To your points below, related to this one about a compression test: it should be done dry and wet- which means putting a bit of engine oil into the cylinder and re-testing. That checks whether the compression loss is from the rings or otherwise, and just how severe.
What really needs to be done is a cylinder leak down test.. that pressurizes the cylinder and holds it... you then see where the pressurized air is leaking.. is it down into the crankcase? Piston rings are shot.. is it into the cooling system, bubbles forming in the radiator or overflow tank? Blown head gasket between the cylinder seal and coolant galleys. Up and into the valve cover? Valves are not sealing for one or more of a half dozen reasons.
You can see just from what we are all posting here, the tests that can and should be done are intensive, specific, and numerous. It sounds like your mechanic is a little old school in that he just does the down and dirty quick tests that worked fine back in the 80s and earlier.
Also, the check engine light blinks when the misfire becomes persistent and severe. All modern vehicles do this as a warning to stop driving the vehicle as the problem has gotten bad enough that damage could occur; as opposed to a random cylinder misfire detected (code P0305), which means that the vehicle detected that sometimes, but not always, cyl 5 has a misfire.
Ty cowboy .The light stays on .Its lost compression. Im far from a mechanic . I appreciate all the help.Im taking your advice sir and going to get another look at it as you said . Last thing I forgot to mention . He said may be gas clog up it up .And to try pure gasoline . What would regular gasoline cause ? Also to the person said use correct coil what is the best to use ? .What brand Thank you very much again
This line about the gas clogging something up sounds like grasping for straws total horse crap. "Pure" gas? I assume he means gasoline without ethanol.. most fuel nowadays is 10% ethanol, an alcohol. Which is also a solvent.. so what the hell is in the gas that is supposed to be clogging only ONE cylinder? it would have to have selected just cylinder 5 fuel injector to clog.. and not the other 5.. what!? why?! how!? No! It's going to clog more than one if you had some containment in the fuel. And it would not necessarily go away for a bit..
Mopar coils are the best to use, as the Jeep prefers and is designed around the factory specified parts. Others have gotten fine results with some specific brands, I don't know which, they'll have to post here or you can search our forum threads- there are posts all about it.
I keep a drawer of 8 mopar coils pulled from a same-year Durango for mine... uncle seized the engine running it without oil and a bad head gasket.. so I snagged the coils since they are the same on the 4.7 as on the 3.7.
I put a post on a you tube Mechanic Scotty.He said
Have someone Test the engines wet and dry compression tests in all cylinders. And if 5 is bad . Engine needs rebuilding ?
Pretty much. If the compression test shows higher compression after performing it wet, with oil added to the cylinder, it indicates, as I previousl said, the piston rings are worn or damaged. This will necessitate a basic lower end rebuild at minimum. New rings, hone the cylinders, probably good time to toss in new crank and rod bearings too, but then you'd want the crankshaft turned. But if the bearings are fine with no signs of abnormal wear, I'd be inclined to just re-ring it and toss it back together.
Scotty Kilmer on you tube said do wet and dry compression tests and if shows 5 is bad engine needs rebulding ? Is this because of carbon on valves or what ?
It's because of worn piston rings. Carbon on valves can be cleaned off, but would not be affected by adding engine oil to the cylinder during a compression test.
During a cylinder leakdown test, however, carbon build up on the valves that is bad enough to keep them from closing properly (and holy hell that would be A LOT of carbon build up) would be evident as the cylinder leaked up and out through those valves.
I feel like this is either an intermittent failure on the fuel injector, or a problem with one of the valve lifters in the head. All/each of those can be replaced on their own provided that there is no further damage.
