Hi guys,
My engine works fine the first five minutes, after it warms up it feels like running with four cylinders. no power at all.
oil/filter ok,fuel filter ok, air filter ok, spark plugs/wires ok, distributor cap/rotor ok, fuel pressure regulator ok, all replaced in the last six months.
Recently I replaced the idler control sensor, O2 sensors, coil and that is it.
what else can I do?
94 ranger 3.0 5 spd

 

Welcome and thanks for joining us at FTE!

 

Welcome to FTE. How's she running when you rev it up? Sounds like the problem is occuring just as she goes into closed loop. In open loop, the computer ignores the O2 sensors. She might be going into limp home mode, but hard to tell so far.

She must be setting codes. Have them read or buy a cheap code reader and get back to us with what you find. Did this start right after you replaced the parts you mentioned?

On Edit: Come to think of it, open loop only lasts for the first minute or so. Check your ECT(engine coolant) sensor. The computer may think the truck is still cold when she warms up.

Fred

 

If you have the stock plastic intake tube that runs from the MAF to the throttle body check it for cracks and splits. My 91 had cracks in the folds and was letting air in after the MAF. Taped up the cracks for awhile until I made my own out of mandrel bent tubing.

 

based on the parts that you have been replacing i assume that you have been fighting a lean condition? Have you done a compression test? you may want to have the heads checked. A crack in a head would not be as noticable until the engine warmed up thus expanding the crack. Are you getting misfire under load? or at all?

 

The timing of the problem would be a key peice of information as well as codes the computer throws. Has this problem just happened suddenly? Has it been happening ever since you replaced everything?

When I went through my plugs/wires/cap last year I reversed cylinders #2 and #3 on the cap when it was all said and done with. It wasnt entirely noticabe as far idle quality, but when driving it felt like something was just a little off the norm. So you might check your firing order next chance you get, its simple enough and will eliminate that possibility.

My thoughts are contrary to cddz. When heating up metal does expand, however it expands in all directions. It wouldnt pull apart a crack. Thats why when an exhaust manifold cracks its loud upon startup, but quiets down once heated up.