Hello to all. Once again I find myself in need of some smart fellers. Have a 99 Ranger, 3.0 flex fuel, distributorless ignition,150,000 miles. 4x4, 410 gears. I am getting an occasional miss while going down the road. usually hits when I am cruising along 55 to 60 mph. Will start to shudder like one of more cylinders are dead. may last a minute, may last a few seconds. May do it two days in a row, may do it two weeks apart. not noticable on hard acceleration or deceleration. may happen while idling, but never develops when idling, but disappears when engine gets over 2500 rpms. Untill I get to cruising speed again. Actually it seems to mimick my son's 99 f 150 when one of the cops went bad. Can the coil pack (square box with six plug wires attached) on the distributorless ignition do the same thing as a bad cop? Or do I need to look some other direction? I have replaced four of the six injectors at different times, but they were always a dead miss. Not throwing any cel codes that my cheap little tool can retrieve. What do y'all think?

 

Without more definitive clues, it's hard to narrow it down to a better guess.

If it seems to happen more on damp days, maybe suspect a cracked spark plug ceramic insulator, flashover from dirty plug insulators, damaged plug wire insulation, or a breakdown in the coilpack.

Most autoparts stores can bench check the coilpack at no cost, but with the problem being intermittent, it's hard to say if a bench test would spot anything.

If the problem occurs when it's damp underhood, I suppose you could try a ignition system "wet down" test, with a spray bottle of water & see if you an get it to act out.

If it seems only to happen after the engine is warm, you could try using a hair dryer, or heat gun to warm the coil pack & see if it'll act out, you could do this during the bench test too.

BUT on the otherhand if it were missing that bad & for that long, it seems to me the computer would have turned the CEL on, or at least set a trouble code of some sort in CM. Is the CEL ok, does it light up during the self test period????

If so & seeing as how we don't know which code reader you have, maybe consider having the computer rescanned at your favorite autoparts store, to see if there are any codes in CM, in case your code reader can't/didn't scan for that.

Post ALL codes found, as they could provide good clues to narrow things down some.

Seeing as how you've had previous fuel injector problems, I suppose you could have another intermittent acting out fuel injector, if so & you suspect they may be dirty/sticking, maybe try a good fuel system cleaner, at the on container specified oz/gal treat rate, at the pump before filling up, like "Techron Concentrate Plus", in a tank of Chevron, Texaco, or CalTex gas, & see what happens.

I see Advance Auto now has 12oz Techron at a "two for one" deal, AutoZone has recently also.

A bunch of thoughts for pondering, let us know how it goes.