Bad shake/miss at cruising speeds

[oachs83]

Have a 2002 Ranger 3.0 with over 200k miles. I have always had a miss or rough idle since I bought it at 190k miles. Also I get a squeal at start up but on wet or damp days it squeals for a long time like a belt noise? Now I latley had a engine light say cylinder 2 miss, that went away and then had a cylinder 4 miss. Plugs and wires and heads are all new as off 190k and good compression. Now I have no engine light but at cruising speeds I get a violent shake but if I hammer the gas it goes away. First thought of unbalanced tires but it happens at 20mph or 60mph it doesnt seem to matter. Also the truck seems to have a real hard time to even stay at a constant 65mph. Any help would be great. Thank You.

 

[TomB1269]

Check for Syncor shaft failure. Easy test, remove serpintine belt and start engine (only ofr a minute) if you here a squeal the its the syncro shaft, if not its just belt and pulleys. It is also the one unit that can have error codes but not throw a CEL as it Cam position sensor on the syncro shaft is not monitored fro faults or errors above 2500rpm.

 

[oachs83]

A little update: It only shakes/misses real bad at 1800-2100 RPM but does idle pretty rough as well.

 

[Rearanger]

I'd do a fuel pressure check. 50-65psi. Try to see if roughness is one cylinder or all. Disconnect one plug wire at a time to see if one cylinder shows no change. How does it behave going up hill under load?

 

[oachs83]

Ill check fuel pressure. As far as under load yes kind of. If you keep on the gas to try and maintain speed at those R's it really shakes for example if I put it on cruise during the miss it will keep missing. But as soon as I do the slightess accel or decel it instantly stops missing as severe.

 

[Rearanger]

But as soon as I do the slightess accel or decel it instantly stops missing as severe.

I'm wondering if a faulty TPS may be doing this? It wouldn't hurt to check it for smooth resistance/volt readings as you slowly depress/release accelerator. You can try to mimic your pedal movements and see if there is unaccounted for fluctuation.

 

[oachs83]

Checked TPS and it is perfect.

 

[oachs83]

Found that after 5k on new plugs the plug in cylinder 2 wsa destroyed. I replaced it and nothing changed. I have spark but the plug is very wet. I tried swaping with the #6 cylinder and did not seem to make a difference?

 

[twonole]

Double check your firing order and check very carefully for burned wires. Also clean your MAF if you haven't already, it can make a world of difference.

 

[oachs83]

So I did a compression check and it is ZERO. Did not even move the needle, the 1 and three cylinders are around 150. In my experience even a hole in the piston would give some compression so I am hopeing it is a stuck valve or something in the head maybe a bad cam lobe? Funny thing is yesterday on my way home it seemed to accelerate real well the last mile or so from home. I also could not get it to buck like it was and the idle seemed much smoother at a stop light. Once I pulled into the driveway though it was rough again but maybe half as bad. I will see how it goes today but thought that was weird.

 

[Rearanger]

Plugs and wires and heads are all new as off 190k and good compression.

I did a compression check and it is ZERO

Too bad after all that work.