Strange Acceleration Problem

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I have an Explorer 2000 4.0 SOHC with no mods.

Yesterday, I was drinving for about an hour without any problems. I stopped on the side of the road, reversed back to read a tourist sign and had it idling for about 5 to 10 minutes. It was a hot day.

When I pulled away, just as it went to change up, the acceleration died. Initially I thought the Tranny had gone but...

I found that if I pushed the accelertor down very slowly, it would slowly get up to speed but if I tried to floor it, it looses all power.

I thought that maybe the idling in hot weather had caused an atomization problem so I stopped, let it cool, disconnected the battery to reset everything.

This did nothing. The strange thing is, in park it will rev up without any problems. It also is idling a little rough now.

I managed to get home by using the cruise control and using tha accelrate button to ease up the speed slowly, when I did this It drove OK. The idea being that it can accelerate more gradule than my size 12 boots can. But on a hill, because Cruise control would try to accelerate, it would start to die again.

So the bottom line is, so long as I accelertae gradually, it is OK. The last thing I noticed was that I had used a lot more gas than usual. 3/4 of a tank on a 45 mile drive.

THe strange thing is that the problem happend very suddenly. I would be a little less suprised if it had started a problem that slowly got worse but this was just sudden. I started to think that stopping, reversing and then idling has caused a problem, which would be odd but may be a clue I guess? or totally unrelated. It just seems strange that after no problems and then stopping it would suddenly occur??

I would appreciate all help as I live in the middle of nowhere, and this comes at a time when my second vehicle is out of commission too.

 

[aldive]

Have you cleaned the MAF, throttle body and the IAC? Also, have you checked the O2 sensors function?

 

[AZoutdoorsman]

im no expert but it sounds like your injectors cant keep up you know what i mean it sounds like its starving the same thing happend to me with a quad (still havent fixed )

hope this helps and it bumps it so good luck

 

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I'm handy but...

I have rebuilt a few engines in the past (pre computer days). I'm very handy but I'm out of date. So..

The O2 Sensor, I think that is in the exhaust manifold right? How do I test that?

The throttle body, I can find ;-) but where are the other sensors? Actually I think the MAF is on top of the TPS? (Is that Mass Air Flow?)

A little extra info please or point me to a good thread thanks..

 

[Nocturnall]

MAF is right after the air filter, it's a part of the tube for the air filter. O2 sensors you have 4. Pre cat which are in both manifolds for the exhaust and post cat which is after the cats obviously. IAC is on the upper intake manifold driver side after the throttle body. Sounds like the engine is flooding or something with that amount of fuel consumption. Check the wiring on the o2 sensors and make sure it's not melted or anything, other then that the only thing to check would be output voltage I would think on those, if you search the site I"m sure somewhere it says what the voltage out of them should be. the MAF check connections, clean with some carb cleaner I beleive and that should take care of that, though that's supposed to clean itself I read.

 

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More Info

I just test drove it again and the key number is around 2.5 to 3k rpm. once it hits that level it starts to die. I also sat and reved it up and when it starts to die, the exhaust gets very black (lean mixture?) so the flooding, or too much gas idea is on the right track. I'll check the O2 wires and look for a voltage thread, I have a multimeter so I can do that, I'll also check the vacume hoses. I'll report back but keep the suggestions coming. You guys are helping a lot.

 

[aldive]

The way to test the O2 sensors is via an OBD II scanner.

 

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Problem Solved - I cannot believe it!

Before you think I'm an idiot, I would like to point out I changed the air filter only a couple of months ago. What I forgot to take account of, is I just moved onto a farm. And I now drive 4 miles on a dusty gravel road every day.

I removed the air cleaner to get access to the MAF and the air cleaner was bulged upwards in the middle, as the engine had literally tried to suck it in. I removed it and sprayed the MAF sensor and bingo. Everything back to normal.

So I guess the answer in may case is a filter change every month!

or a better filter? any suggestions?

 

[Nocturnall]

amsoil ea filters are the most recommended and probably best your going to find. Also they are cleanable.