1998 Ford Explorer timing chain

OK if you would do a compression test on the engine. To do this you get a compression tester and then you remove all the spark plugs and unplug the coil pack. Now put the compression tester in a spark plug hole make sure it is tight and crank it over at least 3 times do this on all cylinders and write the compression down as you go. Now I need you to put a swirt of oil in the cylinders (not all at once) as you check them and not the difference in compression and get back to me with the what you find on the dry and wet test. Is this the OHV 4.0 or the SOHC 4.0 engine? Is there any ticking noise as it is running that sounds like rocker or lifter noise? Get back to me and we will go from there.

OK I have never seen a timing chain cause 1 cylinder to drop. I am not saying that the timing isn't bad it might be but either way will not cause one cylinder to drop. Now a compression test on number 5 cylinder is very important and really should be done so we can see what it is doing and then check compression on another cylinder or 2 to compare it to. Now with that as for pulling the wire and it running the same could be compression, bad plug, bad plug wire, or bad injector. So if you like we can run a couple of tests but you will need a digital mulit meter at one point. Now first when you pull the plug wire is there spark? Have you pulled the plug and checked it? I would not pull the engine as that is not required to check out the basic things that can cause this kind of problem. You only would need to pull the engine to rebuild it. Let me know what you can and if you have a digital multi meter and we will do some tests on the plug wire and the injector.

Ok if you would ohm the spark plug wire and get back to me with the ohm reading and the length of the wire. Also if you would pull number 5 spark plug and see what it looks like, if needed take a pic of it and include and I will look at it for you. I also need you to ohm the injector for that number 5 cylinder. Just simply unplug the injector and ohm across the the terminals of the injector itselft. Get back to me with the informantion and we will see what that tell us.