Hello Im new to the forums, let me start by saying i appreciate any advice you can give, thanks.




I have a 1998 Ford ranger with the 2.5 L 4 cylinder SOHC engine ~120k miles

as of lately i have been having some engine issues, a piston 3 misfire and the truck would get really shaky and sometimes stall when coming to a stop/idle.

I knew it was time to replace my spark plugs, I also changed the ignition coils (both) the spark plug wires and the spark plugs, they worked as i drove the truck around for awhile but was still having the same misfire etc.


after some more research I decided to do a compression test, so i went and got the tester, read up on what i need to do to perform the test, and did so.

This was performed last night I started when my engine was hot, I pulled the fuel pump relay, the wires going to both ignition coils and had taken out all the primary plugs, I was able to do the test and got results, I did a dry and wet test on each cylinder, (using about a tablespoon of new oil in each cylinder) I put everything back together and called it a night, but did not actually start the truck.


This morning i got up rechecked that all wires are correct, and i didn't miss anything last night, relays plugged back in, coil packs plugged in, etc.

I went to start it and it would barely turn over once, after 2 tries all it does is click now, not once but just continuously as long as i have the ignition turned, (didn't do so for long as i don't want to ruin anything else)

I pulled the spark plugs out all seems fine, from what i could tell there was some gas on them I got a faint smell of fuel on one, and i decided to see if I could do a compression test again too see if id get results since i was sure the spark plugs are working, and the fuel pump and injectors are working. after getting it set up again to try the test (this time the engines cold) I turn the ignition and all i get is continuous clicks. cant even do the test.


so my question is what suggestions do you have? what could have went wrong, did i screw up by not running the engine after i put some oil in it when doing the wet compression test?

I don't think my battery is dead, usually that will just click once or ill hear a turnover and then that's it.

are the pistons perhaps stuck, or is that not a possibility, any help would be appreciated thanks.


*edit I am charging the battery now as it was showing as low on the dash, i really hope this is the issue

 

Welcome to the forum

Your battery is low or cables are loose
It is possible the starter motor got overheated from doing compression test, and is now going bad
Starter motor is usually only used for a few seconds at a time and only a few times a day, so compression tests are hard on them, no way around it through, but if starter was near end of life then that can put it over the edge.

This also wears down the battery ALOT
Battery is also only used a few seconds and a few times a day
After engine starts the alternator takes over and provides ALL THE POWER for the vehicle, battery is only used for starting the engine, after that it gets a trickle charge from alternator to keep it topped up for the next time it is needed

Check battery voltage, 12.3v to 12.8 volts is OK
12.2v or under is a dead battery
Try recharging it

If battery voltage is OK then check battery cables at BOTH ENDS of each larger cable
If connections are clean and dry then starter motor is probably drawing too many AMPS

Post compression test results
2.5l runs 9.1:1 ratio so you should expect 160-170psi, dry-wet

Both Spark Plugs in each cylinder fire at the same time, common misinformation is that they alternate, they don't
So a Spark misfire is fairly rare because both spark plugs would have to misfire for the cylinder to not fire.
You can unhook either coil pack and engine will still start and run, a little less power but still run OK, and this is also a way to test if a spark plug or wire or coil pack has a problem, i.e. engine runs fine with only Exhaust spark plugs on, and misses with only intake side spark plugs on, so intake side spark plugs or wires or coil pack has a problem

Dual spark plugs are more efficient and give better performance.
Why don't more engines use that?
Because its very hard to add a 2nd spark plug in a head, no room for it, lol.
And with newer swirl design heads and 4 valves the 2nd spark plug doesn't help that much any more

 

Thank you so much for all the information, that really will help me a lot, It did end up starting after i got it on a charger, still ran as bad as it has been.

Im going to make a seperate post relating to the issues i have been dealing with, so far I am starting to think that my piston rings are worn.

The test results were as follows DRY: Cyl 1 = 100 Cyl 2 = 80 Cyl 3 = 70 Cyl 4 = 100 WET: Cyl 1 = 160 Cyl 2 = 110 Cyl 3 = 100 Cyl 4 = 150
there is one thing I must do before i can trust these results the only thing i didn't do when running these tests was open the throttle, I understand that could affect the results?
I was going to rerun the test one more time or at least the dry one to see if there is any change.

I might as well ask while Im at it, if I were to be correct and lets say the piston rings are worn, if i take the engine apart and have a machine shop resurface and sleeve or bore (i dont know all the terms or things that can be done, still doing my research) is there a chance i would only have to have that done to the cylinder head and not the lower half of the engine?

 

Yes, test results do point to bad rings

Best way to do compression test on fuel injected engines
Cold engine
Remove all spark plugs, in your case(dual spark plugs) remove 1 spark plug from each cylinder, doesn't matter which one, with spark plugs removed crank will have better cranking speed for more accurate test results, and even, i.e. if a few cylinders have good compression they will slow down the crank effecting test results, with no compression on any cylinder except the cylinder being tested the results will be equal testing.

Install compression gauge
In the cab, press gas pedal down to the floor and hold it down, this turns OFF the fuel injectors while cranking and opens throttle plate all the way for good air flow
Crank engine until you hear 5 or 6 "hits" of the compression stroke on cylinder being tested
Turn key off
Check gauge, write it down
You can do WET test in the same cylinder now or move to next cylinder, doesn't matter

Before doing a compression test I would test engine vacuum if it is running, vacuum gauge is $20-$25 and can tell you ALOT about any gasoline engine
Good read here on testing: https://www.gregsengine.com/using-a-vacuum-gauge.html

A plugged exhaust will have low vacuum and compression readings

Your big increase WET would indicate a ring issue, BUT...................all 4 cylinders?????? that would be very rare with 120k miles, even at 400k miles, 1 or 2 maybe not all 4