1995 Ford Explorer can't idle, runs rough, when re-starting

ford
engines
explorer

#1

1995 Ford Explorer Limited

4.0L V6, Auto



Problem: Car is running rough and unable to idle after engine is shut off and restarted before completely cooling off (2+hours).

Problem frequency increases as outside temperature increases (above 70F).



It sounds like the car is missing on 1 or 2 cylinders and takes almost 1/3 pedal travel just to keep it running over 1000rpm. After keeping the engine going like this for 5-10 minutes it begins to idle normally.



Car has been to mechanic several times, $$$ spent on tune up and diagnostic. Of course problem never happens when he has it.



My guess would be something has become sensitive to the heat under the hood…either computer related or perhaps the ignition coil?



Any suggestions? Things to check?



Thanks in advance,



Mrsouka




#2

problems with the idle air controller seem to be fairly common in Fords, judging from the postings here.


#3

Any competent mechanic should be able to diagnose an idle air control problem. What you likely have here is a fuel pressure leak down problem. The fuel pressure regulator valve seat can wear on these and cause this problem. This can cause a vapor lock situation because the pump only turns on for 5 seconds until the engine starts. Turning the key to ON about every 10 seconds 4 times before starting the engine can usually clear the bubble. You could invest in a new fuel pressure regulator for about $60 since there is no way to test this item. Disconnect battery after replacement to reset the computer so it learns the new regulator.


#4

would the pressure regulator explain why it takes 5+ minutes for the idle and engine missing to go away?

Also if it were an idle air controller issue, why would the engine run so rough for a few mintues after restarting?


#5

Judging from what you’ve posted here so far, I’m to understand that the vehicle idles/runs fine after it’s been started cold and kept running, correct? So it can’t be ignition problems because these would usually be prevalent across the board (hot/cold/fresh start/restart, etc). Also it’s not something that’s heat sensitive because if the vehicle as been started cold then continues to run fine after it’s been warmed then that can’t be the issue either. You said you’ve paid $$$ for diagnostics, what were the results of these? Have you gotten any second opinions? Are there any DTC’s associated with this problem you are having? I somewhat agree w/ the fuel situation posted above, you need to start by testing the fuel pressure…What you are looking for is a weak fuel pump. My experience has been that w/ these odd/tough to troubleshoot problems like the one you are having, have almost always been electrical. I’d concentrate my efforts on the electrical side of the fuel management system, or the Engine management system.


#6

There are some pretty strange problems that can happen with this regulator. Some of these were made with the spring slightly off center and that causes the seat to wear on just one side. At best this causes a small hole in the seat and a leak down condition. In other cases it will cause the valve to stick open. This can cause near stalling at stoplights when vacuum is the highest or high load like climbing hills. I even had one that would cause the engine to stall on on high speed right turn exit ramps. Another traditional problem is a small leak in the diaphragm. The seat wear problem can even become worse with a new pump with higher flow. In this system about 80% of fuel is bypassed back to the tank when the engine is running. A general health of the fuel system can be checked by measuring fuel pump current at the fuse. Should be about 3.5A and under 2.5A the engine will start to stall. Someone with sharp diagnostic skills can solve this problem, don’t expect it from your mechanic. If you decide to just throw more money at the problem, the FPR would be a good choice. Can you provide any more info on problems when driving?


#7

some vehicles have a cold start injector with a timer that injects fuel for a few seconds when the vehicle first starts. could be the injector timer is staying on to long. i dont know if this truck has it or not but you might check on it.


#8

Before commiting to electrical/computer issues I"m going to focus on fuel supply diagnosis first.

Per info below, I’m going to check the fuel pump current and see if it’s in spec (or about 3.5A per suggestion).

Then I’m borrowing a friends fuel pressure guage and will hook up and test where I can…and will see if its in spec.

Will check ign.on, engine idle, engine at 2k RPM, and pressure when goosing the gas.

I’ll keep the guage in my Explorer…and when the problem happens I should be able to attach it to the fuel rail and check the pressure…I suspect pressure will be sub-par…

I’ll update my findings later when I get data


#9

Great advice Opera House.

I have 1995 Ford Ranger with 3.0L 6 Cylinder engine. Manual transmission.

When the engine is warm and the temperature outside is hot, the engine over-idles. That is when come up to a red light the engine is idling high enough to start off up-hill without giving it gas. I turn the air-conditioner off and back on, and it drops to normal for a
short while.

I have also observed that the engine never starts when I first hit the key, but if I turn the key, stop and try again, the second time is a charm. I just read about the fuel pressure regulator valve, and tried the Turning the “key to ON about every 10 seconds 4 times before starting the engine” trick and by golly that worked.

This problem has lasted about 3 years. It has been in the shop dozens of times. They don’t charge me to look at it. We are all looking for a solution. I can go all winter without seeing the problem, so it is heat-related. This is Texas and when the temperature goes
over 90, the problem will be there.

We replaced vacuum lines, ECM computer twice, oxygen sensor, ECR valves, plugs, wires, throttle clean.

My question is could the fuel pressure regulator valve have a heat-related problem?