It starts, but it doesn't continue to run.

[SportEX95]

Okay, 95 Explorer Sport. 4 Liter OHV engine. Starts but won't keep running with throttle closed. Will run for 3-5 min. throttle open at least half way then slowly dies. Will start again hours later. After cools down plugs wet with gas & carbon fouled. Has low vacuum when running. 40 PSI at fuel rail, stays around 38PSI, 30 min. after key off. Starts easily, almost wants to idle. After running catalytic converter glows red...Disconnected muffler but had no effect on symptoms.

New: Catalytic converter,intake air control valve, coil pack, plug wires, plugs, upper intake manifold gasket, cleaned MAF sensor & Intake air temp. sensor. Have two PCM's both same symptoms. New air filter, oil and filter, new fuel filter.
EGR valve blocked by temporary blocking plate, so not a factor, vacuum line disconnected & plugged as well.

HELLLLP MR. WIZARD!!!!!

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the stock 95-01 section. Do you have a check engine light with codes?

 

[SportEX95]

got parts for LED to check codes last night. Will check codes tonight by connecting jumper to under hood connector and will use 12V LED instead of analog voltmeter. My Explorer has a test port under the hood and under the dash. My OBDII reader gives communicatiuon error when I connect. My connector under the dash fits the OBD II reader but it has fewer pins populated than the OBD II port in my 99 Yukon. Thanks!

 

[2000StreetRod]

too rich

It sounds like your fuel mixture is very rich which is why it only runs when cold and the catalytic converter is overheating. Is there black smoke in the exhaust?

Are your pre-cat O2 sensors connected? The PCM will increase the richness until it sees an overrich condition reported by the O2 sensors.

Have you tested your TPS? TPS Test Procedure

Have you cleaned and then tested your MAF sensor? MAF Sensor Test Procedure

 

[SportEX95]

Thanks for your response. You've given me some very usefull leads to follow, and some much needed specs.! No black smoke that I've seen, but I'm usually working on it at night...Will keep my eye open for it. The O2 sensors are connected, one is new because someone prev. to me had dented the casing and I wanted to eliminate poss. prob. with it. This year only has Pre. Conv. O2 sensors.

 

[imp]

Leaking injector/injectors. Might be worth investing in a new set, after all the other work/$$ spent, easy job. WARNING: I could be all wet! imp

 

[SportEX95]

Thanks Imp! The fuel pressure remains around 40PSI with key off for at least 30-40 min. This should mean no leaky injectors...I haven't checked it any later than that so it may stay at that range longer.

 

[imp]

Thanks Imp! The fuel pressure remains around 40PSI with key off for at least 30-40 min. This should mean no leaky injectors...I haven't checked it any later than that so it may stay at that range longer.

Sorry, we struck out on the injectors.........but pressure holding up this long rules out other problem areas, too, so now.....I'm stuck......Others' ideas?? imp

 

[SportEX95]

So, I think I have eliminated any possible vacuum leaks. Eliminated EGR(installed blocking plate on flange side, disconnected and plugged vacuum hose to diaphragm), car still starts, runs if I keep foot on gas and will run around 3000RPM or above at command from throttle for a couple minutes, I can hear buildup of fuel accumulate in exhaust manifold(I think) and then it slowly dies...It will start again in a few minutes, but with diminishing return each successive time. Tried disconnecting MAF(got backprobe reading of 2V KOEO) but it ran worse and lasted shorter time. One O2 sensor is new. If the old one is bad, will the PCM command too much fuel if readings conflict? Cannot get this thing to idle.

 

[2000StreetRod]

TPS test results?

Did you test the TPS?

Carefully check the hose/tube that connects to the IAC valve for breaks/leaks.

Do you have any trouble codes?

 

[2000StreetRod]

MAF sensor

When you test the MAF sensor it should remain connected to the PCM. The PCM provides the power for it to function.

 

[budwich]

back up a bit.... you indicated a "low vacuum when running"... is that with the throttle cracked or just during the initial start? I don't think that sounds quite right, shouldn't it have high vacuum with little or no throttle? You might do a compression check on a few cylinders to see if the mechanicals are sane.

Further IF your have vacuum issues, then you likely have fuel regulation issues cause they are tied together... based on your "fuel splash out the back", I would say you have no regulation... maybe.... kind of what you see is what you get.

 

[SportEX95]

When you test the MAF sensor it should remain connected to the PCM. The PCM provides the power for it to function.

In response to your posts I followed your procedures from an earlier post of yours on 12/8 and tested the TPS and the MAF. TPS checked good both for resistance and KOEO voltage backprobe. The IAC is new, will check plumbing. MAF read 2V KOEO(connected). I bought an analog voltmeter last night, will check codes in a bit.

 

[SportEX95]

back up a bit.... you indicated a "low vacuum when running"... is that with the throttle cracked or just during the initial start? I don't think that sounds quite right, shouldn't it have high vacuum with little or no throttle? You might do a compression check on a few cylinders to see if the mechanicals are sane.

Further IF your have vacuum issues, then you likely have fuel regulation issues cause they are tied together... based on your "fuel splash out the back", I would say you have no regulation... maybe.... kind of what you see is what you get.

When I did the vacuum test the engine was running at around 3000RPM so throttle open however much that required. Maybe 1/3 open. Had to do that to keep it running. Fuel press. held steady around 40PSI. After cool down, pulled plugs and they were wet with fuel...

 

[budwich]

ok... but when you are cranking the engine, no gas, what is your vacuum reading? Further is your vacuum "responding" to your pedal movements? Of course, the compression test might help if one is possible. Lastly, monitor your injectors for "pulses" to see if you are getting any (should).... just to see if your cam sensor is "functioning".

 

[SportEX95]

I am not getting any codes at all. I get Batt. voltage from pin 4 of the test connector with no jumper, or with when key is on.

 

[SportEX95]

So it was the transmission!!!

Weeeelllll, would you believe the transmission was the problem? There was a catastrophic failure in the transmission that caused a short in the wiring harness which allows the Trans. to talk to the computer. This is why there were no trouble codes and it kept the computer from working properly which caused the engine to run way too rich. This is why I was seeing Batt voltage at the readout pin of the test connector.

Anybody got a good deal on a Transmission in working condition? In the Seattle area?

 

[BrooklynBay]

Thanks for the update! How did you make this discovery?

 

[SportEX95]

After all the good advice from you guys and testing everything on the engine and finding no hard failures, I finally bought an analog voltmeter and discovered that the computer wasn't generating any codes at all. I was getting steady battery voltage at the signal out pin of the test connector under the hood with the jumper installed. Both key on /engine off as well as key off. This made me decide enough was enough! I took it in to a Ford dealership for diagniosis. They pulled their hair out for a day and called to tell me it was a short in the Transmission wiring harness that talks to the computer. This caused the computer to lock up or lie and made the mixture extremely rich. They said when they disconnected the connector from the tranny the engine ran great!

When they pulled the pan to replace the harness they found one of the belts hanging loose, a bolt in the pan, some torn gasket material and metal filings scattered around...

The tranny had been rebuilt a few months before failure(prev. owner)

 

[SportEX95]

Hey! check out the final story on this! It's at the end of my post...