I have a 1993 ranger 2.3 l engine. Did a compression check on my engine and every cylinder is widely different. Compression test s are from 186 down to 107. Motor says it has 96, 000 plus miles but I don't know if it was turned over or not. Truck otherwise is in really good shape. Not losing any oil or using any oil and tailpipe is not carboned up or wet. It's dry and carbon free. Runs fairly well but Lacks power especially on the freeway when you want to try and get around a slow driver. Car idles nice and drives nice otherwise. Can't understand the wides spread in compression. Can't understand how it rides so nice with that widely varying compression. No problems in the radiator acting like a compressor tank. What can I do to try and maybe clean the inside of the engine and even out the compression?

 

Welcome to the forum

Compression test needs to start with all cylinders at 0 compression, 4cyl, V6 or V8
So in the case of the dual spark plug 2.3l Lima engine you remove 1 spark plug from each cylinder, doesn't matter which one
Now engine will crank at the same speed for each cylinder being tested
Test a cylinder by hearing 5 "hits" at least, you will know what a "hit" is
Write down results
Test the next cylinder

Widely varying results can be from cranking speed, so good battery is a must, also why spark plug must all be out, higher compression cylinders SLOW DOWN the crank so throw of results in cylinder being tested
Compression is a temporary thing, metal on metal is NOT a good air tight seal, lol
Running compression is only about 70% of static compression, so 150psi static = 105psi running compression
Adjacent cylinders can share a blown head gasket, so just lower compression, no other issues at that time
If #2 and #3 were both lower than #1 and #4 then that could be the case
Or #1 and #2 were lower than #3 and #4

Post current results
#1
#2
#3
#4

 

[QUOTE=RonD;2223884]Welcome to the forum

Compression test needs to start with all cylinders at 0 compression, 4cyl, V6 or V8
So in the case of the dual spark plug 2.3l Lima engine you remove 1 spark plug from each cylinder, doesn't matter which one
Now engine will crank at the same speed for each cylinder being tested
Test a cylinder by hearing 5 "hits" at least, you will know what a "hit" is
Write down results
Test the next cylinder

Widely varying results can be from cranking speed, so good battery is a must, also why spark plug must all be out, higher compression cylinders SLOW DOWN the crank so throw of results in cylinder being tested
Compression is a temporary thing, metal on metal is NOT a good air tight seal, lol
Running compression is only about 70% of static compression, so 150psi static = 105psi running compression
Adjacent cylinders can share a blown head gasket, so just lower compression, no other issues at that time
If #2 and #3 were both lower than #1 and #4 then that could be the case
Or #1 and #2 were lower than #3 and #4

Post current results
#1- 165
#2- 109
#3- 185
#4- 177
These are averages. Seven cycles each test three times per cylinder. Removed all the plugs from the exhaust side, because it's much easier. Nothing showing a bad head gasket that I understand would be there if two adjoining cylinders we're down on compression, but I don't have that. Spark plug looks nice clean. I'm leaning more towards carbon following maybe on the higher compression cylinders and maybe a sticky valve on the low compression cylinders. I however am not a pro at this stuff but that's just my guess.

 

1990-1993 2.3l runs 9.2 compression ratio(CR). 1994-1997 ran 9.4CR

Common rule of thumb is CR x 18 = expected static compression on a cold engine
9.2 x 18 = 165.6psi
18 comes from air pressure at sea level to 2,000ft, 15psi, then 3 psi for the mechanical compression of that air pressure

So yes you could have some carbon build up in 3 and 4, on regular gas you should get some pinging/knocking on acceleration, do you?
Working EGR system might keep that from happening, so it's not happening, lol

You can added a teaspoon of oil to #2 and retest(WET test), if PSI doesn't come up to say 165 then its a valve that leaking
Wet test will always make PSI go up in any cylinder as it seals the rings better, but not the valves
So if the 109psi only goes up to 120-140 then a valve is leaking

 

Do not have any problems with knocking or pinging. Haven't done a wet test or leak down test yet. Everything runs good except some lack of power. It may just be my feeling because I haven't driver a 4 banger in so long but I still feel like it has more to give than it is. Did seafoam through the throttle body with a hot soak about a month ago but didn't seem to make much difference. It's just confusing to see compression all over the place.

 

The 109 is the only one out of the 10% average

Another rule of thumb on compression tests is
Don't use the highest or the lowest numbers, and add up the others then divide by that number of cylinders
In your 4 cyl 177 + 165 = 342 for 2 cylinders
Then divide by 2, 342 / 2 = 171psi average

Expected differences can be up to 10% and still considered "normal"
17psi is 10%
171 + 17(10%) = 188psi
171 - 17(10%) = 154psi
So expected range will be 154 to 188

#3 185psi is within normal range, high side but not a big concern

Any cylinders under 154psi will have an issue, like your #2
Obviously with 6 and 8 cylinders you get a better average


The 1989 thru 1997 2.3l Lima's have dual spark plugs for extra power
But you can't tell if 1 spark plug or even whole coil pack is not working because engine runs fine with 7 spark plugs or 4, lol, 2.3l Lima ran fine from 1974 thru 1988 on just 4 spark plugs

So a test you can do is to have the engine running/idling and unplug the 3 wire connector on one coil pack, so engine is only running on the OTHER coil pack
Should idle smooth, if you get a misfire then one, or more, of the spark plugs on the working coil pack is bad, or the wire

Then reverse it, plug coil pack back in and unplug the other one, to test both coil packs and other 4 spark plugs
Engine should idle smooth on either coil pack and its 4 spark plugs, can even drive it that way, same as 1974 thru 1988, just less power

 

I will try the coil packs as you suggested tomorrow as well as the oil test and I will let you know the results of that.
I may try some seafoam in the crank case as they require, change the oil and filter and see if that may free up a possible sticky valve problem in the next couple days.
Hope you catch those results when I'm done.
Thank you for the info so far, much appreciated!
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Sorry it took so long to post, had a death in the family. Anyway, on the brighter side, I did the coil pack test that you mentioned and everything seems good. I did a two-day soak with some Gumout tune up in the cylinders and I got some good readings. The number two cylinder that was down to 109 PSI ran up to 120 PSI. That's a good improvement and I'm happy with that but I know it may not be the best. I was surprised how that worked out just from a soak. Also put some oil in the cylinder and ran another compression test and it came up to 127 PSI. It leaked down to about 122 and held there for about 5 minutes or better. So there was a bit of a leaf but not too bad and it just stayed at 122 so things must be sealing up okay now. Smoked out the neighborhood burning out the gum out however, haha, but it seemed to help out. So right now I thought I'd try some techtron in the fuel tank and I put the appropriate amount of seafoam in the crankcase to help clean things up. So I'll run about 250 or 300 miles and drain the oil change the filter and see what happens after that. Hopefully that gets rid of some carbon and maybe on the valve still and maybe it'll steal a lot better. I'm hoping for the best.