[Sitting Bull]

I have a 1999 Ford Ranger with a 4 Cyl. and in Cyl. 3 it has Low Compression 124 PSI, I would like to know what would be the cause of this?

I have changed my oil every 3,000 miles and Ford Garage told me that the engine is as clean as a new one. They could not gave me a reason why this CYL is low. It has 105,400 miles on it.

When I get up to 37 miles per hour you can notice that it wants to run rough, but than when you get up to 50 it seems as if it goes away.

[Henry Highrise]

This is the Introduction forum....It would be best to ask your question over in the Engine forum...that way the folks with the answers will see it.

[SSedan64]

Usually a valve or compression ring leaking. It can happen no matter how well maintaned is has been.
Sounds like fuel or ignition on the rough running. Tuneup/fuel filter

[Sitting Bull]

Originally Posted by SSedan64

Usually a valve or compression ring leaking. It can happen no matter how well maintaned is has been.
Sounds like fuel or ignition on the rough running. Tuneup/fuel filter

I had a TUNE-UP and a NEW FUEL FILTER and TIMING BELT put on a month ago.

Do you think Engine Restorer would help?? How can you tell if it would be a valve? Hope it is not a ring.

[poncho62]

moving it........

[Henry Highrise]

What are the readings on the other cyls.?

[oldbogie]

Originally Posted by Sitting Bull

I have a 1999 Ford Ranger with a 4 Cyl. and in Cyl. 3 it has Low Compression 124 PSI, I would like to know what would be the cause of this?

I have changed my oil every 3,000 miles and Ford Garage told me that the engine is as clean as a new one. They could not gave me a reason why this CYL is low. It has 105,400 miles on it.

When I get up to 37 miles per hour you can notice that it wants to run rough, but than when you get up to 50 it seems as if it goes away.

Low compared to what? The other cylinders or the book? Do you have a compression history so you know what it's doing over time?

Bogie

[F&J]

Have a "leak down" test done. It will tell.

[machine shop tom]

Your engine is notorious for having preignition and detonation damage, whether is it the 2.0 or 2.3. Most of the time this is caused by an improperly or non-functioning EGR valve, although just overloading (towing a trailer for example) while using 87 octane fuel can cause it as well.

Perform a leakdown test on it. If the valves are not the problem, it's likely that you have piston and ring damage.

tom

[Hippie]

Originally Posted by machine shop tom

Your engine is notorious for having preignition and detonation damage, whether is it the 2.0 or 2.3. Most of the time this is caused by an improperly or non-functioning EGR valve, although just overloading (towing a trailer for example) while using 87 octane fuel can cause it as well.

Perform a leakdown test on it. If the valves are not the problem, it's likely that you have piston and ring damage.

tom

2nd that and my past experience with them has been that they will often burn a hole in number 3 piston .............

[coldknock]

Most of the Ford-Bangers I see have a chunk of the ring land gone on #3 or one of the exhaust valves is toast.

If you don't have the proper gauges for a leak down test you could simply wet the cylinder with some oil and do another compression test. If the pressure goes up then you have a busted piston/ring. If the pressure stays the same then it's time for a valve job.



Larry

[Sitting Bull]

What Am I Talking In Cost To Fix The Problem?

[Hippie]

Originally Posted by Sitting Bull

What Am I Talking In Cost To Fix The Problem?

You need to determine what the exact problem is first. You've been given some good diagnostic tips here, try those first and let us know what happens.

[Sitting Bull]

Originally Posted by Hippie

You need to determine what the exact problem is first. You've been given some good diagnostic tips here, try those first and let us know what happens.

I know Ford told me that compared with the other CYLS. NO. 3 had 124 psi I really don't know what the other one was, they could have told me and when I hear 124 it stayed with me. What is the compression supposed to be?

I know they wanted me to order a long block for it and it would cost $4,000.00 and I said no. the way I see it you would have $6,000.00 in it.

[Dale T.]

125# compression is NOT bad compression. Bad compression is 75-0# compression. Have you checked out the other cylinder compression or just the one? What is the compression in the other cylinders?
You can have up to a 25% difference between cylinders and still be considered "normal". A cyl. needs 50-75 minimum to fire, you may have a vacuum leak in a vacuum hose ar Fords were notorious for the upper intake plenum gasket sucking in and causing a vac leak. The EGR valve would also wear and start sucking air around the shaft.
Spray some carb spray around the base of the upper plenum and the EGR valve and see if your miss goes away. BE CAREFUL carb spray is very flammable and if your spark plug wires are borderline cause a spark you have a fire on your hands, have a fire extinguisher close by.
The other thing do you have any fuel getting to the cylinder? Do you have a plugged fuel injector,are you getting an electrical pulse to the injector, how about spark? swap plug wires and then plugs between cyl.#3 and another cyl. that you know runs, does the miss change cyls. also?
This is a good start, if problem continues you may want to brig it to a mechanic for further tests. Have fun, Dale