Mechanics

TRUCK SEEMS TO MISS A CYLINDER WHEN IDLE

1994 Ford Ranger

Engine Mechanical problem
1994 Ford Ranger 6 cyl Two Wheel Drive Automatic 262000 miles

After a long dedicated 14 years, thhr ranger is beginning to act up. Have replaced fuel pump, fuel filter, spark plugs wires etc. But the engine seems to be missing firing on a cylinder when idling. When under power, it seems that the truck is going to buckle over and shudders very badly. The fuel pressure is good @45psi. The transmission has about 160000 on it. It was running ok till I decided to do some PM on it and has never been like before. Every mechanic has pointed in every different direction. The truck passed emissions with flying colors two weeks ago when the problem was intermittent. Now it is continuous. Compression in cylinder 3 is 75psi(as per the repair shop). What should I do next and what is the problem?
Thanks for your help.
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Kbhatia007
August 27, 2008.



260,000 miles is phenominal.

It may be time for a engine overhaul, sounds like the rings are wearing, how did a wet compression test handle? The pressure go up significantly?

75 is pretty low and will definetely make a missfire very noticble at low speeds.

Blackop555
Aug 27, 2008.
Will be doing a wet test in a couple of days, but everybody wants me to swap the engine out, which I am very hesitant to do. Want to rebuild the head and the valves if that sounds like it will solve the problem. If the pressure comes up with the wet test then only I will swap the engine.(Indicating bad rings). We will know pretty soon.

Tiny
Kbhatia007
Aug 28, 2008.
Rebuilding the heads as you suggest could work if the rings arent worn.

Might be time to checking the bearings also. The rings could be worn, the cylinders are probably worn.

Blackop555
Aug 28, 2008.
Thanks blackop555 : -))
We will know better tomorrow after the wet test. I think that will decide if I need to swap the engine of work the valves and the heads. I really do appreciate your input. Let us wait and seee.

Tiny
Kbhatia007
Aug 28, 2008.
No problem, I hope the best cheapest way for you!

If you need further assistance im here to help!

Blackop555
Aug 28, 2008.
Hello blackop555: This time did the compression test myself and found that all cyls had roughly 170psi after 5 piston strokes.
Too high but seems to me that the mechanic could be wrong. Now does that point to a clogged convertor? Two independent mechanics have already told me that there is metal coming out of the tail pipe. Truck drove smooth after I assembled the plugs back in the cylinder
really confused now.

Tiny
Kbhatia007
Aug 30, 2008.
Hmm 170psi is a bit high, maybe a camshaft issue wouldnt worry as long as its runnign good now, could be that a spark plug wire was loose on the plug or damaged and when you were moving them around it made the wire complete connection again.

Would like you to check on that one cylinder momentarly see if when the engine runs rough if the compression drops back down.

Blackop555
Aug 30, 2008.
I realy appreciate you hanging in there for me and geting me through this, blackop555.
It is back to where we started. I will run over the truck to a muffler place to make sure the converter is not clogged. There are two holes on the side and I can feel the exhaust coming out of there. It has not run bad on idle and city driving like before, but definitely feels as if it is missing. The same vibrations on park and idle and same when the transmission is engaged with brakes on. The worst part is tat it is not displaying any codes. Says everything is good.

Tiny
Kbhatia007
Aug 30, 2008.
Thats what im here for.

Chances all that would show up is a missfire code. But since pre obd2 didnt have missfire detection. It wont show up.

Blackop555
Aug 31, 2008.
Interesting observation. The truck has been running fine today(when it is a lot cooler here in Atlanta), but yesterday when it was hot, it acted up after running a few miles and being turned off in a parking lot. Hmm. What can it be?
There was no sign of a skip and the acceleration seemed normal. Idle rpm was higher. Is it a bad fuel pump out of the box? Not being able to keep the prime?. Or is it the ecm not geting fed back properly rom one of the sensors (the brake light does not come on when I engage the parking brake). Btw, in summer time in georgia, the ethanol content can go upto as high as 10%.
So here you go blackop555, does any of it make sense?
Thanks again

Tiny
Kbhatia007
Sep 1, 2008.
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