98 ford explorer stalling, error 171 174

[hsd]

1998 Ford Explorer Sport 2 Dr sohc
~175k km on it

Well here is the situation. For the past month, the first time I use the truck each day, it'll start up, then immediately die. So I need to keep my foot on the accelerator anywhere from a few minutes to 10+ minutes. Problem does seem to go away once the engine has warmed up. Also the idling on the truck seems low, almost to the point of stalling out, or it does stall out if the truck hasn't warmed up enough. Idles under 1k rpm, usually around 600rpm. Getting error 171 and 174. I've looked up the codes and they list several possible issues. Get no other errors codes other than these two.

I had this issue last year, but it wasn't nearly as severe.

Other work I've had done on the truck in the past two years, spark plugs and hoses replaced, thermostat, alternator, and muffler. As well as regular oil changes, using 10w40 for past two years. The truck is in good condition overall, have always kept up with any issues that came up.

Thoughts?

[shorod]

Welcome to the forum!

Why are you using 10W40? Do you otherwise have significant oil leaks?

When you have your foot on the throttle to keep the vehicle running, does the engine run roughly (assuming you are keeping the engine speed around 1000 rpms) or smooth?

The P0171 and P0174 could easily be due to unmetered air entering the intake. Unmetered air would be any air entering after the Mass Air Flow (MAF) sensor. This could be due to intake air tubing that is not properly connected, a bad vacuum hose, or other vacuum leak.

The idle issue could also be due to the unmetered air, especially if the leak is sufficient enough to cause a rough idle. If the engine is smooth when running, then I'd suspect you also have a bad Idle Air Control (IAC) servo. These are pretty common to fail and cause hard starting and idle issues on cold engines with no other symptoms when off idle.

-Rod

[hsd]

Originally Posted by shorod

Welcome to the forum!

Why are you using 10W40? Do you otherwise have significant oil leaks?

No leaks been keeping an eye on the oil level, was having issues with truck running a bit rough, was told to try a thicker oil. It did seem to run smoother afterwards. So I kept on using it. Think I should try going back down to 10w30?

Originally Posted by shorod

When you have your foot on the throttle to keep the vehicle running, does the engine run roughly (assuming you are keeping the engine speed around 1000 rpms) or smooth?

Hard to describe, I wouldn't say it is rough, but I usually keep the foot on it to get it between 1000-2000 rpm. Today for instance the first time I used the truck was 3pm, it was around 10C (about 50 fahrenheit), w/o the foot on the accelerator it got going, then slowly the rpm went down, help out at around 500rpm and then died. Didn't take long to run smooth after with foot on accelerator.

I tried looking for air leaks, by was unable to spot anything. Though then again I probably don't really know what I'm looking for. Read somewhere I may be able to hear the air leak in some parts.

By idle air control servo, is that the same as the idle air control valve?

Thanks for the advice, and haven't had to deal with any local mechanics, wanted to get a bit informed before trying to find a place to get it worked on, or perhaps do the work myself. Any ballpark figure on repair cost? The idle air control valve seems to be around $100 at various part shops here. Seems like an easy fix I can do myself, if that is where the problem is. If not then the harder job will be to find a mechanic I can trust.

[hsd]

Hmm just found something on cleaning the iac, will give that a try tomorrow. I believe I have some carb cleaner spray, that should work? If that fails I'll replace the part, failing that will take it to a mechanic.

http://www.ford-trucks.com/article/i...r_IAC_Fix.html
that is another link I found, I've got a multimeter somewhere and will try that as well.

Gotta love how auto problems happen right after you've paid tuition/rent, bleh.

[shorod]

Yeah, carb cleaner spray should be fine for cleaning the IAC. You'll want to spray out the passages for the IAC as well, which is the same as the idle air control valve.

As for the oil, I'd suggest you use what the manufacturer recommends, either 5W30 or possibly 10W30. It should be listed in the owner's manual. For your location 10W30 may be fine. If nothing else it should improve fuel economy slightly. If the engine runs roughly with 10W30, something else is wrong, it's not the oil. That "something else" could be part of what's causing the stalling.

-Rod

[hsd]

Originally Posted by shorod

Yeah, carb cleaner spray should be fine for cleaning the IAC. You'll want to spray out the passages for the IAC as well, which is the same as the idle air control valve.

As for the oil, I'd suggest you use what the manufacturer recommends, either 5W30 or possibly 10W30. It should be listed in the owner's manual. For your location 10W30 may be fine. If nothing else it should improve fuel economy slightly. If the engine runs roughly with 10W30, something else is wrong, it's not the oil. That "something else" could be part of what's causing the stalling.

-Rod

Ok here is what I did today. I cleaned the iac, also took a multimeter to it. according to the info I found the resistance should be between 7-13 ohms, it's at 10.5, so iac doesn't need to be replaced. Went ahead and cleaned the maf as well and tested with multimeter.

Temp today was 15c (60F), after holding foot on accelerator a minute or so, put the truck into drive and was ok. At first didn't feel like it had the power, then it took off.

Will be doing an oil change tomorrow, 5w30 is indicated by the manual, by probably will go with 10w30. Filters were nice and clean.

Thanks again for the advice, will see what news tomorrow brings. Mentioned the problem to a friend, turns out he did car work for a living for a while, he'll take a look at it on sunday. But at this point I gotta see if I can get it fixed myself for my own satisfaction

[hsd]

Just a quick wrapup, truck works like a champ now. Seems the only issue was it needed a good cleaning, and increasing the idle. Did an oil change as well. Cleared the codes, will give it a few days and hope for the best.

[danielsatur]

Also consider a good Smoke test, see www.youtube.com/watch?v=FfiQ7qWiG-M

[hsd]

Originally Posted by danielsatur

Also consider a good Smoke test, see www.youtube.com/watch?v=FfiQ7qWiG-M

Will mention this to my friend, perhaps he can borrow one from his workplace. After watching that video, I'm sure I'll find some leaks in mine as well heh. Truck has been running well last 2 days, so we'll see.