I have a 93 f250 w/5.8 L. was running fine when i parked it, two days later started it up and won't idle, have to keep on the gas to keep it running. So bad i am afraid to drive it anywhere. After starting it a couple of times, now it won't even start. Pulled codes with key on engine off and got 114(Air Charge Temperature sensor-signal voltage higher or lower than expected) and 636(Transmission oil Temp sensor high or low voltage). 172 was in memory which is Heated Exhaust Gas Oxygen sensor rich Bank 1 which i assume is a vacuum leak somewhere. Would any of these cause it to run that bad or not start??

 

Codes 114 and 636 are expected when you run the KOEO test on a cold engine. You are supposed to warm it up first. Naturally, you can't because it won't start.

Code 172 means the oxygen sensor is dead or the engine really is too rich. Reasons could include a failed fuel pressure regulator (dumping fuel through the vacuum line), leaking fuel injector (peeing fuel when it should be shut off), incorrect fuel pressure (causing excessive fuel for a given injector on time), blocked fuel return line.

This may not be the reason for your no start, unless there is so much fuel it is practically running out the tailpipe.

On a no start, you first need to make sure you have spark. If you have a tach, you can verify spark by looking to see if you see 200 to 300 RPM during crank. Another test is to listen for the fuel pump. It should come on with the key, shut off after two seconds, turn on during crank, and shut off 1 to 2 seconds after you release the key from crank. If there is no PIP signal from the TFI, the fuel pump will not run during crank, the PCM will not turn on the injectors, and there will be no spark.

Or you could check for spark the old fashioned way -- use a timing light, an old spark plug, or hold one plug wire close to a good ground.

If there is spark, your next check is whether there is no fuel or too much fuel. Ideally, you have a fuel pressure guage and can check pressure at the rail. If you don't have a guage, at least push in the stem with your finger and see if there is any pressure at all. If it looks like there is fuel pressure present, try flooring the accellerator during crank. This should put the engine into "clear flood" mode, and if it starts will confirm the possibility of "too much fuel".

If she still won't start, pull one spark plug and see if it is dry or wet with gas.

 

Thanks for the reply. i think it wouldn't start cause i had cranked on it a lot and was only about 18 degrees out. I charged it over night. Today started right up, had to keep my foot on the gas to keep it running. Ran rough until it got warm, almost to the normal on gauge. Tried to test with it running, wouldn't give codes. Tried again with engine off. 111, no problems. In memory 332,172,173 which is insufficient egr flow, too rich, too lean. Haven't had a chance to drive it. seems better whens it's warm it just won't idle until it's warmed up and almost sounds like a miss even warm.

 

Check your fuel pressure, check for vacuum leaks, check the oxygen sensors.