New here; need help with a low idle issue

[frenchqtrchef]

Hello everyone. I just joined; I am having a problem with my truck and I'm looking for some opinions. I have a 2000 Exp 5.4L engine. When I start the truck, the RPMs immediately go down to around 400. I have to rev the engine up around 2000 RPMs for a few minutes, or else when I let off the gas it will die. When I come to a stop, if the truck is in 1st gear, I have to let off the gas very gradually and apply the brake very slowly - if I take my foot off the gas pedal suddenly, and apply the brake quickly, it will stall. It seems as though the longer I drive, the less chance there is of stalling, but the RPMs never go higher than 500. The engine light goes off and on randomly, as does the oil pressure light.

In addition, this is an intermittent problem. It comes and goes every two weeks or so, and lasts a few days. I never know when it's going to happen, and I never know when it's going to return to normal. When it does return to normal, it's as if the engine will finally "catch". I don't know any other way to describe it, and yes I am a woman. Sometimes when it does "catch", I'll hear the automatic door lock mechanism. Yesterday morning when I left my house, it started up and ran like normal. When I got in it to leave for lunch, the low idle problem began again. I haven't noticed anything that triggers the problem; i.e., wet weather, hot temperatures, etc. The last time this happened, for a few days it would do the idling low thing after being started, and then the RPMs would immediately go back up to normal (around 1000 for my truck). It did this every time it was started, for about a week, and then everything returned to normal. The time before that, it had been happening for a few days, and then one day it rained hard and I had to use my wipers on the highest speed, and as soon as I did this, the engine went back to normal. It's the strangest thing.

I have been using the same mechanic for years, and I feel like he really knows his stuff, but even HE hasn't been able to figure out the problem. I believe he said the code he got from the engine had to do with a coil, but that it didn't need to be replaced yet, and I believe he said the coil wouldn't be the cause of these symptoms. My husband has replaced the idle control valve and the fuel filter, and that hasn't helped. Any ideas?? Any suggestions? I don't want to put a lot of money into the truck, as my husband is pushing me to get something new at the beginning of the year, but I do need the truck to get me from point A to point B until then, and preferably without leaving me stranded somewhere.

**Another symptom I just thought of - the interior lights and the headlights will flicker and get brighter/dimmer with the revolutions of the engine. Also, the battery light will come on and will blink, but it blinks in such a way that makes it seem like there is some kind of short. The oil pressure gauge light that comes on randomly was checked and the mechanic said there was nothing wrong with the oil pressure at all, so maybe this is an electrical problem? The alternator was replaced in February of 2008; I was driving on the interstate when it went out and these symptoms are not the same at all.

***Well, yet another symptom I just thought of - when this problem is occurring, the headlights are very, very dim, until you press down on the gas pedal. Also - the A/C does not blow cold unless you're pressing down on the gas pedal. As soon as I take my foot off the gas, the lights go dim again and the air isn't cold.

 

[huklebuk]

Try cleaning the throttle body, or it could be the idle air control valve. Mine was the throttle body dirty. But I just read on another thread that the idle air control valve can also cause problems.

 

[frenchqtrchef]

My husband replaced the IAC, but there was no improvement. I will tell him about the throttle body cleaning.

 

[huklebuk]

Also if there is a coil pack going bad, it is going to go bad and will misfire at the worst possible time. I know this from personal experience. The only real solution is to replace them all. They tend to go bad around the same time, and replace all the plugs as well. There is a chance that the electrical issues could be caused by weak coils misfiring. Use only motorcraft standard plugs, I tried using another plug and it blew the plug out. Hope this helps some.

 

[Expeditionary]

easy to say replace all the coils... i have an engine miss but I live with it. Its not that bad and the truck has never stalled. However I cant tow my boat far because of it.

Coil packs run $50 each... $50 x 8 = $400!!!

 

[huklebuk]

easy to say replace all the coils... i have an engine miss but I live with it. Its not that bad and the truck has never stalled. However I cant tow my boat far because of it.

Coil packs run $50 each... $50 x 8 = $400!!!

Oh I know its not cheap thats for sure. However I am going with personal experience replacing the coils all at once. I had 3 coil packs go bad at different times within 3 months. Once I was able to get home and do the repair myself. The other two I was out of town, once had to have it towed the sound was so bad. After that I just changed them all to prevent any further issues. They are good for about 100k so its not like you have to do it often. The one time I had to have it towed it cost me 175 for the tow and another 300 for the repair. I'm all about the ounce of prevention versus a pound of cure.

 

[frenchqtrchef]

Unfortunately, cleaning the throttle body didn't work. My husband has mentioned bad coils, but says that half of them are hard to get to, and it's hard to tell which one(s) are bad? Seems like the mechanic would have been able to tell if that was the problem, though. Maybe I just need to bring it back in. Usually the problem has stopped by now, but this time it's still stalling and idling very low.

 

[Nas1]

Have you had your alternator checked? It could be the voltage regulator going bad on the back of it or it could be the alternator itself. To me it sound like that would be the issue.

 

[huklebuk]

As a last resort you can take it to the dealership and have them run diagnostics. Thats the only way you will know for sure which (if any) coils are going bad and what other problems there are.

Edit: Thats a good call on the alternator Nas1, with the electrical issues that could be the cause.

 

[frenchqtrchef]

Had the alternator replaced in Feb of 2009; how long are they supposed to last? I'm not having the same symptoms I did when it went out the last time, but I'm sure that doesn't mean anything. My husband agreed that the alternator could be the problem. It just stumps me why the mechanic wouldn't have found that.

True to form, last Wednesday everything went back to normal. I stopped to pick something up on the way home from work and when I got back in the truck it fired right up with no issues, and it's been running normal ever since.

I did notice yesterday and especially today, when I first start the truck up, the engine doesn't want to turn over at first, and then once it does, all gauges max out and stay there for a few seconds, and then return to normal. Isn't that something that can happen when the battery is going bad - which could also involve the alternator?

 

[huklebuk]

Yes the battery could be going bad and causing those symptoms. Its a crapshoot on replacement alternators. I had one go bad on another vehicle after only 5 months so it really depends. Arent Expeditions fun?

 

[frenchqtrchef]

5 months?? That's crazy! Husband replaced the battery, but it's still acting up. Now he thinks its the starter. Of course, that won't fix the low idle issue. I really love my Expedition, but there are so many little things that are starting to come up lately that it's probably time to get rid of it. I have to say, though, for a truck that's almost 12 years old, and with almost 135K miles on it, I feel like we got way more than our money's worth. The problems only began in the last year or so. It has been such a reliable vehicle. Husband wants to get something different, but I am pushing for another Expedition!

 

[callee11]

My thoughts on this is im thinking its the alternator as someone already stated.... A regulator going bad inside the alt can give you very irratic and intermittent problems.... your mechanic may have checked it out but if the regulator wasnt acting up when he checked it, it would have looked like everything was fine.... something like this is difficult to diagnose cause seems like every time you want to do some checks then the problem goes away (dont fix what aint broken)... but if it were me... I would change the alt out and go from there

 

[markanthony]

Just a side thought. There is a little rubber hose and a 90 angle off the valve cover. I would try there. the other one I can think of is to clean the mass air flow sensor, the intake air temp sensor, the throttle position sensor, and replace the pcv valve.

yes the coils are hard to get to. if you pull the fuel rail bolts, and move to the side. You do not have to really unplug or pull the injectors apart. I found that my local auto store had a set of accell coils for around 300 bucks. they were cheaper then oem and MUCH cheaper then dealer...

I would also think about a cat going bad. If it is getting plugged it would not allow the exhaust to flow and "stall " the engine. I got an laser therm checker and use it to see what my cats temp was. before the cats should be preaty hot. the cats themselves should be really hot then the after the cat should be a little cooler then both. I am not sure what temps the should be. but if there is not heat temp difference in any of it. I would think a cat is not working. If the cat is not burning off the extra fuel. The 02 sensors before and after the cat will show it to have to much fuel and cut it back. This may cause it to run this way as well.

 

[huklebuk]

I would think its got to be throwing codes at this point. I would take it to autozone and borrow their code reader. If the check engine light is going on and off its got to have a code. If the cats are clogged this should also show up on code.

 

[05Bandit]

My 05 had the same problem you are describing but through a low idle code everytime. I replaced the throttle position sensor that didn't work. I sprayed some throttle body cleaner in the throttle body and that didn't work. So i finally pulled off the throttle body and there was so much build up of carbon and other stuff that the butterfly was completly sealed when it was closed. When i cleaned out all the carbon i could see that fuel/air could now pass through the sides of the butterfly at idle... This fixed my idle problem and took about thirty minutes..

05Bandit

 

[frenchqtrchef]

Callee11 - you are so right - every single time I bring it to the mechanic, it stops acting up. Every time. I had an appointment with him a couple of weeks ago and the night before, it started running right. It's very frustrating.

markanthony - I will show my husband your reply.

huklebuk - I took it to Autozone on Thursday of last week. The not so helpful clerk tried to get the codes for me but said there was a fuse blown in my truck and she wouldn't be able to read the codes. I asked her to check the battery as well, and she said she couldn't get a reading on it either. She said it was either so low or there was too much corrosion (I did see what I thought was a lot of corrosion). I went ahead and bought a battery, but the next day the problem stopped. This morning I got in the truck and when I turned the key there was a clicking noise, and the engine wouldn't turn over. I assume this is the starter?

 

[frenchqtrchef]

Wow, 05Bandit - that sounds like a simple and easy fix. I'm going to show this thread to my husband so he can try this if he hasn't already.

 

[callee11]

The clicking noise is most likley the battery/corrosion on the cables.... pull the batt clean the cables with a wire brush and install your new battery if it still does it after all that then i would say its the starter but change batt and clean cables first

 

[huklebuk]

I've never heard of a fuse blown not being able to pull codes but ok I guess it could happen... I use coke to clean my batteries and cables in a pinch, the soda neutralizes all the battery acid and stuff that builds up from time to time. Check to make sure the connections are all tight on the connectors as well, they work loose sometimes. I would go back to autozone and ask for someone who is more helpful. Sounds to me like they didnt know what they were doing. In order to test the battery they have a cart they usually roll out. Sounds to me like the person you got was new. The codes are easy to get, the instructions are generally with the code reader and dont involve much more than 1) turn on reader,insert plug into obd II port 2) turn key to on position and read the codes. Its a pretty straight forward process.