HELP! 1994 2.3l ranger stumbles on acceleration

[iank1]

OK here's the story. 1994 Ranger 2.3l manual, 2WD no AC. the engine light has been on for some time. I tried reading the codes, but I got different codes every time and researching what I got led me nowhere. SO I replaced the air filter, fuel filter, PCV, DPFE, TPS, ICM. I Tested the fuel pump, good, tested the MAS, good, tested the crank sensor, good. NOW, the engine light is off, BUT the engine stumbles HARD on acceleration. If I feather the throttle SLOWLY it revs out to red line. IF I open it up fast it pulses like a rev limiter (WAH WAH WAH WAH WAH). I tried putting the old ICM back in and the truck runs fine but on 6 of 8 plugs and the engine light comes back on. why would a new ICM cause this? could it be the bad ICM was not responding to a faulty O2 sensor? ARG! I need the truck for work and I need it to pass smog! I think I need a hug too....

 

[HAPPY+RANGER+GUY]

Did you do a hard reset on the computer? Let it sit several minutes with battery disconnected and see if still behaves same way.

 

[used to be a chevy man]

Hi. I'm a 93 ford ranger owner. If your truck only does this when its hot then you probably have the same problem I'm having. I noticed it likes to stumble an die in traffic but rarely driving down the road. Feathering the throttle works too. Anyways. I am led to believe we both have a CPS that is going out. To know for sure check not for fuel pressure but correct injector response when it starts acting up. All you need is a test light. If you get a bad injector response it's definitely not the icm. Like you I have replaced about every electronic under the hood including the computer and it just keeps getting worse. I also replaced my timing belt which wasnt even bad but im not about to swap it again. If you replace your CPS and it does not help you may want to replace your head gasket because you may have cylinder to cylinder bleeding. Check compression first to be sure.

I hope this helps and god bless.

 

[used to be a chevy man]

By the way a CPS on its way out will test good so it is futile to test it unless your vehicle is currently having the stumbling problem

 

[iank1]

UPDATE: I replaced the cheap aftermarket ICM with a motorcraft one from a wreck. Now the engine light went out, but smog test showed it as a gross polluter. So I went driving around and the engine light came back on. The code was 172 (lack of oxygen sensor signal/ lean bank #2) . So I've been letting it run with some of that 104 golden juice in the tank hoping to burn the CAT clean enough to pass, and lo and behold, the engine light went off. Plus the lean condition seems to have drastically improved as the exhaust is no longer eye burning. No idea if it will pass yet. We'll see.

 

[tomw]

A dirty or un-responsive MAF will caust stumble on acceleration. Low fuel pressure or volume can also affect the injector ability to flow a bit more juice on acceleration causing stumble.
The P0172 code is from the 'downstream' O2 sensor. It is monitoring the catalytic converter efficiency, and does not 'flip' like the upstream sensor does. If it is low, either it is gone, the wires are chafed/shorted etc, or there is a problem. Lean means there are O2 molecules in the exhaust, such that they were not all consumed by the fuel, so it must be lean to have extra Oxygen .. or there is a leak adding oxygen, or the wires are as noted, etc.
tom

 

[bmerr98]

I had a diaphragm go bad in an egr valve a while back. It let enough extra air (unfiltered at that) into the sysrem to throw a lean code and the CEL but I don't recall much else for symptoms.