Hi all,
Just thought I'd post my problem here and see if maybe someone else has run into/heard of a similar issue. Any and all suggestions are appreciated.
My truck is a 2001 Explorer Sport, 4WD, 4.0L 6cyl 5-speed automatic. Fully loaded minus leather seats and engine block heater. Currently it has about 42,000 miles. on it.
My problem cropped up about a month ago, but only happened about 3 times.
I would start my truck, and it would immediately stall after ignition. At first I thought maybe I was letting go of the key too quickly. I would start it again, give the gas pedal a small tap, and it was fine.
About a week or so after that, the problem started happening nearly every time I started the truck. At first, giving it a little gas after ignition would do the trick, but then after a few more days, I'd have to keep my foot on the gas for a minute or two to keep it running. (Maintaining normal idle RPM of about 750-1000)
Then it got worse, and I started having to drive with both feet (using left foot for brake) until after a variable length of time passed, and it would run perfectly normal. (Thankfully my first 12 years driving were spent in 5-speed manual vehicles.)
Now, it never "corrects" itself, and if I take my foot off the gas too abruptly, it stalls. Odd thing is, if I lower the RPM slowly, it doesn't stall, but it idles at almost 500 RPM exactly. This is about 250 RPM lower than normal for my truck.
And just tonight, the CHECK ENGINE light came on for the first time. Of course I've been checking everything since the problem first became common, and everything I can check is fine.
I've followed the maintenance schedule to the letter, all of which has been performed by the dealership. (I know, that could be the problem right there. *sigh*.)
In any event, my first thought was that I needed some fuel injector cleaner. I used two bottles of the STP stuff in the past 3 weeks, which obviously didn't help.
My next thought is maybe the fuel filter needs changing. Who knows, maybe the dealer didn't actually replace it at 36,000 miles, or maybe they put in a bad one. I'll try that over the weekend.
I've also considered fouled plugs, but I've noticed no loss of horsepower (not that my perception is any good rule of measure) nor misfiring. When I'm out on the highway and can maintain RPM above 1000, it picks up when it's supposed to, shifts as smooth as it did the day I drove it home, and sounds completely normal.
My final thought is that something has gone wrong with the sensors or control unit for the fuel system. Maybe it has become corrupted somehow, and has adjusted the fuel system/idle speed improperly, or has failed completely and isn't doing anything at all.
It's been a long time since I seriously worked on any cars or trucks, but is a Stall Speed Converter still called that, and is it possible that sensors for it have failed? It seems extra odd to me that if I ease down on the gas, it will maintain idle at 500 RPM, but if I just let off the gas completely, the rapidly falling RPM causes a stall.
Anyway, thanks in advance for any suggestions. As I said, I'm going to try the fuel filter first, but I'm not too confident about it fixing the problem.
Thanks again,
Godflesh