i just bought an 85 ranger, 2.3, 5 speed manual, 130,000 miles, 2WD. the truck had a rough idle when i bought it, so i went through and replaced many of the tuneup parts including the air filter, plugs, wires, cap, rotor, and fuel filter. for a few weeks after this tuneup the truck ran just great, but then it began to hesitate sometimes while i was driving it as if it was not getting enough gas, or missing a cylinder. when i stepped harder on the gas it would seem to come out of the problem, but once i resumed normal gas provisions it would have the same problem. i checked the fuel system, replaced the frame mounted fuel pump, and added fuel injector cleaner. this seemed to help, but the problem would still occur from time to time, so i pulled out the plugs to find them all in good order.

soon after this i developed a miss that would occur whenever i accelerated. also, the overheating light on the dash flashes to the tune of the miss, and the gas gauge now has a tendency to jump around oddly. the truck idles just fine, but when i try to go anywhere the miss is there, i have a definite lack of power, and a noticeable smell of gas fills my garage. i pulled the codes, which indicated a problem with the egr solenoid. i replaced this part, and cleaned the egr valve really well. one thing that i noticed while doing this cleaning was that the tube that connects the egr valve to the exhaust manifold, and the inlet off the egr valve into the throttle body were quite full of carbon gunk, which i did my best to clean out, though im not sure i got it all. after cleaning all this, i re-ran the codes, and there were no error codes this time. still, the truck runs with the same miss, and im running out of patience and ideas. any ideas would be helpful and appreciated.

thanks

 

 

If the lights on the dash are a-flashing, I'd bet you have a loose ground wire somewhere, or a loose connection. Look around under the black box cover on the pass side under the hood, where the egr vacuum valves are located. You might also have a perforated plastic tube, flopping in the breeze in time to the engine miss, causing a lean condition to occur. A miss that comes and goes is harder to find.
The TPS can have a bad spot that will NOT throw a code. Use an analog volt/ohm meter to check for dropouts and bumps in the TPS. I'd also clean the IAC, and check the PVC. Last but not least are the TFI and internal pickup in the dist, but they generally do not cause poor idle and miss, they just die. Also, the MAP sensor will cause a rambling idle, but not a miss, per se.
Can you push in the EGR mechanically at idle(behind the vacuum diaphragm). If so, and the idle gets worse, the EGR is working. If the idle does not get worse, the EGR may not be going fully closed (dirty valve seat, whatever), or the passage to the intake is plugged.
tom

 

i checked all that you said, and found nothing out of the ordinary. i checked the compression in each of the cylinders, 1,2,and 3 were at about 120 lbs/in (?) but the 4th cylinder went up to about 150 lbs/in. i dont know what this indicates. the plugs, which were replaced about 1000 miles ago (bosch platinum) were pretty carbon covered. i replaced them with motorcraft plugs, and the miss went away for a day or two. now it is starting to miss again, and i have noticed that my gas mileage is terrible. i am assuming that the new plugs are just becoming fouled again, but i dont know what is causing it. please help.