I have been trying to figure out this for about 1 month. The story goes my dad had a 94 explorer EB sitting in his back yard with a blown head gasket. He told me to come and get it out of his yard. I put 2 new head gaskets on last month and it ran fine for about a week. Fuel pump sparaticly came on when u started it but ran fine after it started. replaced the fuel pump and fixed that problem. After that it got to where when u started it u had to pump the gas like it had a carb. when it did start it idled @2500 to 3000 rpm. I also noticed i lost my overdrive. I cleaned the MASS air and installed a new filter (air). Also intalled a new idle air valve. Still same problem. Went and got a new computer, still same problem. I did notice when i changed out the ecm it started correctly and idled fine and my overdrive worked, but when i got home and went to crank it same problems were back. Now it will turn over fine, just no start. I reset the computer yesterday and got it to crank but this morning no start. Could this be the Mass air sensor? I have a service manual and checked it like the manual stated, it has power and voltage is right. Also whatever is causing my idle to be so high is also causing me to lose my overdrive. I also was thinking a vacuum leak so i have replaced the hoses and
put another intake gasket on (thinking I made a mistake the first time around.). I have also put a new vacuum modulator valve on. It was sucking trans fluid up to my throttle body. Sorry to be so long winded but I am running out of options. Any help would be appreciated.
Thanks,
Kevin

 

Kind of hard to follow. If I understood correctly, I would start with the most pressing problem 1st: namely the no-start. No starts on these (assuming the starter is doing it's part) are either 1) no fuel to the engine or 2) no spark or both. 1st things I would check:

1) Fuel pump coming on?
2) Correct fuel pressure at fuel rail?
3) Spark plugs firing?
4) Any codes in the computer (some no starts leave clues in the computer)?

 

Your first problem is calling your Explorer and exploder. What kind of respect do you think your rig will have for you if you call it a bomb?

Why did you change the PCM? And what PCM did you put in it? These are not like your run of the mill Intel Pentium 4's that will run all the old and new Windows programs. (I know - I work at Intel and your EEC-IV has an Intel processor.) Ford has dozens of PCM's with different calibratiuon codes and different wiring pinnouts. I think, not sure, but I think all 94 Explorers came with sequential fuel injection. If you got a 93 or earlier federal PCM, it had mulitport fuel injection - different pinouts for the injectors. And would not even run.

But it seems your rig does run, right. Just it idles high. The PCM is very repeatable. It only goes high idle per the program and given inputs. A cold motor will idle high and then slowly work down to about 650 RPM - about a minute or so. A hot engine will crank up to 1,200 - 1,500 RPM to help emmisions - all at idle. This is how the PCM is programmed.

See here for more info http://www.fordfuelinjection.com/

When you change a PCM, or just disconnect the battery for 5 minutes, you clear the KAM - Keep alive memory. This is the "learned" correction factors that the PCM stores in response to out of condition emission components. If a O2 sensor is going bad, the PCM tries to compensate - for example. So I would venture to guess you have a problem with a sensor or an engine control device. When you clear KAM - all is good but then the PCM learns a new condition and compensates - but the wrong way since there is a device problem giving the wrong data to the PCM.

You must have a CEL light comming on. What computer codes are being thrown? Go to Auto zone or equivalnet to get a computer code reading.

As far as losing overdrive - that's what you get for buying an automatic. - Sorry, I'm biased. But seriously, this is probably related to the other engine control issues. If you have OD once clearing KAM but then it goes away - it is computer related. If you never have OD - it could be the tranny itself - needs a fluid change or new valve body or even just a vacuum modulator.

 

I am assuming "the bomb" has a great sense of humor. At least it hasn't totally craped out on me. Well, all joking aside.

I have narrowed the no start down to the crankshaft sensor. I am going to replace it this afternoon. As for the PCM, I was hoping with all the problems I was having maybe it was the PCM. We match the numbers up and I ordered the same PCM that was in it, but I am still having the high idle and no OD as before I changed the PCM. Actually changing the PCM didn't change a thing. Is anyone having the problems with the high idle. Oh, I can reset the computer and sometimes it will crank and idle fine for a few minutes then back to idling high.
Thanks for input,
Kevin

 

High idle could be due to bad IAC valve if you have no other computer codes. The IAC valve has no feedback to the PCM and thus would not throw a code if bad. Can be cleaned but doesn't always work. May need replacing.

 

i have already put a new IAC valve on.