93 Explorer dies when I press accelerator

[HP Hatecraft]

Greetings helpful people! (I've been here before)

My 93 Explorer is acting oddly and I'm hoping someone here can point me in the right direction. Here are the symptoms:

It runs fine, if you able to get it out of the driveway. What happens is that the truck starts, then struggles to idle, and dies immediately if I press the accelerator.

4 times out of 5 it will idle on its own for about 15 seconds and then die. 1 time out of 5 it will remain idling and I can try to coax it out of the driveway, without touching the accelerator.

So what I have to do is let it struggle to idle, hope that it will keep running, and then after a few minutes I can very gently touch the accelerator and it will very, very slowly creep out of my driveway and down the street--if I more than brush the accelerator for the first half mile or so, she dies.

After that, she responds normally.

I've been told it may be the mass airflow sensor or the throttle position sensor...and since those are expensive, I'd like to find out how to troubleshoot this problem so I can buy the right part the first time.

If you will, please tell me what you would check first and how you would go about checking it...I realize that I will have to buy an electrical device (don't know the name) to check voltage output (?) so if you can be specific about the tools needed, I'd appreciate it.

 

[Roadrunner777]

Hi,
do you have a check engine light on? Also, do you have the skills to measure voltage and resistance?

 

[HP Hatecraft]

Hi,
do you have a check engine light on? Also, do you have the skills to measure voltage and resistance?

Thanks for the quick response.

No, the check engine light does not come on while it is (barely) idling and no, I do not have any automotive skills whatsoever...but I can follow instructions, so I'm hoping someone can tell me what I need to buy to check voltage and resistance...and then tell me how to do it or point me toward directions for a novice.

 

[Roadrunner777]

I took a hard second read at your original post, based on the no check engine light. So, we are not going electrical to start, we are going to fuel. The shortcut to the end is that I am suggesting the fuel pressure test (follow link in my signature) or if you feel lucky, you could pre-emptively replace the fuel filter. If you have not changed the fuel filter yet, it would not be money wasted to do so. But, if you prefer a more methodical approach, do the fuel pressure test, and post your results here.

Good Luck!

 

[HP Hatecraft]

I took a hard second read at your original post, based on the no check engine light. So, we are not going electrical to start, we are going to fuel. The shortcut to the end is that I am suggesting the fuel pressure test (follow link in my signature) or if you feel lucky, you could pre-emptively replace the fuel filter. If you have not changed the fuel filter yet, it would not be money wasted to do so. But, if you prefer a more methodical approach, do the fuel pressure test, and post your results here.

Good Luck!

Thanks, I will do the fuel pressure test and report the results. The fuel pump was replaced recently, and I bought a new filter but the guy forgot to replace it.

The idle problem existed prior to the fuel pump change, but not to this degree. (and was different in that I HAD to pump the accelerator furiously to keep it running...not lightly tap it or it would die)

I just went out and started it, and what happens now is this:

I start it and it idles at around 1200 rpm's for about 15 seconds, then dies.

I restart it, and just as the rpm's start to drop from 1200, I very lightly touch the accelerator and it jumps back up to 12-1500 rpm's and remains running. I did that (lightly tap the accelerator every 15 seconds or so) for about 4 minutes, then took my foot completely away from the accelerator and it died within 30 seconds.

If I do anything more than lightly tap the accelerator, it dies.

 

[Roadrunner777]

Ok, I'm still going with fuel issue until we know we have good pressure, and maybe we can get that new filter installed.

 

[HP Hatecraft]

I found someone to put the new fuel filter on in the morning, and I'm going to have him perform the fuel pressure test at that time.


Meanwhile, here is more information that might help someone who knows about these things diagnose it:

I just drove it, and the severe idle problem only occurs when it is first started.

I drove for 15 minutes and then parked it for an hour, then went to restart and it started right up, no (or at least very little) idle problems.

So...it seems to happen only until the engine warms up (I'm in Texas, so it doesn't take long). It is REALLY difficult to keep it idling until it warms up...so if those symptoms ring a bell for anyone, please let me know what you think.

 

[Roadrunner777]

Good deal, please make sure they do the pressure test when the engine is cold and having the problem, of course.

Do you get get a check engine light while turning the key to start, even a blink?

 

[HP Hatecraft]

I feel kind of dumb, but I realized yesterday evening that a lot of my truck's problem(s) would be solved with a new battery.

That's why the problem is worse now than before the truck set up for months...duh, the battery has lost its ability to hold a full charge....so everything electrical is getting juice, but not quite enough juice it appears.

I noticed this after hooking it up to a battery charger and having it start right up. It doesn't solve the idle problem, but it does make it where I only have to crank it once or twice and then lightly tap it to keep it running, instead of trying for 20 minutes to get it started and stay started.

I unplugged the MAF (?) and the check engine light came on.

I plugged that back in and then unplugged the IAC with no appreciable difference in the way it was idling...does this point to the IAC being bad?

Thanks for your help Roadrunner.


ETA Do you get get a check engine light while turning the key to start, even a blink?

The check engine light comes on when I turn the key on, but goes off when it starts.

 

[Roadrunner777]

Yes, it does... It has an electrical part and a mechanical air valve part. It is fairly easily cleaned if you take it off, you can see sort of how it works. I'd take it out, clean up the valve side and make sure the shaft moves freely in and out of the electronic side.

 

[HP Hatecraft]

What should the truck do when I unplug the IAC? Would that normally cause it to idle rougher...or should it completely die?

 

[Roadrunner777]

I just tried it on mine. It won't start unless I give it a little throttle. It won't idle at all. And, no check engine light.

 

[Mr. Squeaky]

Did you ever find a solution to this? Mine started doing this last week.

 

[Roadrunner777]

The original poster has not been here in 9 years, so I'm guessing he won't reply. However, the troubleshooting chain is the same:
1) Do you have a check engine light? If so, work out the code(s) and see where it goes.
2) Remove and clean the MAF and IAC, and while you have the MAF off, check the plastic duct to the throttle body for cracks/damage, particularly underneath.
3) Test the MAF with this website: Part 1 -How to Test the Ford Mass Air Flow (MAF) Sensor

If you have a variation on the original poster's symptoms, I would also verify the vacuum lines and fuel pressure.