Poor starts, dying at idle: IACV, Mass Air ??

[Explorer Lee]

I have an '02 Explorer 4.6 Limited with 50,000 miles and about three weeks ago on very hot days it would be a little hesitant to start, catch and run. Then it started to die when I'd let it idle really regularly but normally I could keep it running by feathering the throttle above idle. It was never had a Check Engine light illuminate. Now it has gotten progressively worse regardless of the temp and no it is hard to start and make it catch and run evenly.

I have read a number of threads that sound like the Idle Air Control or the Mass Air sensor could be out. It is a third car with the worst mileage so it has sat in the garage for a few weeks but I need it reliable to tow the racecar next weekend. My wife drove it regulalry last and it seems to get worse and do it most of the time now.

The other day after sitting a week, I drove it to Autozone to get them to read the codes and it started and ran just fine. Since the CEL light was not on, they refused to check the codes but offered to sell my a reader for $279. It really burned me up as the next guy in line behind me they happily read his codes for free and he explained exactly the same "dying at idle" situation I have. The counter guy was adamant that "no CEL = no read" even if I promised to buy whatever part the car said it needed on the spot.

I drove home and it ran great. I put it in the garage and went to move it once each of the next two days and it doesn't want to start easily or really run at all plus it clatters and the exhaust smells super rich. No doubt something is very wrong. I've done a bunch of searching here but am still stumped as to which if either it might be.

Can someone give me some insight? This is my first ever Ford and I'd rather not spend nearly $300 on a code reader plus buy the parts. Does a bad IACV give codes but not CEL and make hard starting? Does this sound more like the Mass Air sensor even though I have no CEL? The IACV is a $90 part and no one near here stocks it. The Mass Air is about $150. I'll do what I need to get it running but I'd rather not buy both (probably wouldn't be able to return an unused one) as a shot in the dark. Have been lovin' my 'Sploder until now.

 

[Explorer Lee]

Any thoughts? I don't have enough posts to put this in the 911 category but it is nearly an emergency as I don't go racing next weekend if I can't make the tow vehicle run. That would suck if the racecar is ready and the tow car isn't.

 

[spindlecone]

Try Cleaning the IAC and the MAF

 

[TPLYNCH]

IAC will not throw codes. How long was the truck sitting? If a long time, did you put any gas stabilizer in the tank. You may have h2o in the tank. Also check air intake and filter and make sure no furry creature made himself a bed. Cleaning IAC and MAF won't hurt either.

 

[Explorer Lee]

It has sat for a week or two since this problem began but normally it gets used once or twice per week so it is not a dead fuel issue. It made a 1300 mile trip in early July.

The Mass Air Sensor is clean as a whistle, looks pretty perfect and new and definitely nothing that should be cleaned. The IAS looks generally alright as well but internally had a light coating of carbon or dark dust on the inner works. I shot some brake cleaner in and swished it around but I doubt it really did anything. Certainly nothing that looked like it would be considered "dirty" or had gotten to the point that it would not work.

I did see that the paper air filter was quite dirty, time to get the K&N that I have planned on but had yet to do. Although it was pretty nasty, I don't think it was blocked enough to cause a running problem. As clean as the other parts were, the filter was obviously doing its job.

I'm a bit stumped but I'll go get a new air filter and then see if I can limp it to anotehr Autozone and see if they will check for codes.

 

[spindlecone]

Lee
you cannot see a dirty Maf, takes a miniscule amount of contaminantes to foul it, clean it,JMO

 

[Explorer Lee]

I'll go head and clean the Mass Air Sensor as well. Will a good solvent like brake clean and air be sufficient?

Just for grins in case it was a totally plugged air filter (the dream easy fix), I left the filter element out and took it for about a 1/4 mile test drive and it died probably ten times near idle (once while actually in gear and driving) and was poor starting back up.

Since there is still no CEL, looks like tomorrow I'll get a K&N and an IACV and hope that's the trick.

 

[spindlecone]

No, use electrical contact cleaner and DO NOT hit the contacts with compressed air
Nough said, good luck

 

[Explorer Lee]

Great, thanks for the input. Much appreciated.

 

[Explorer Lee]

Solved it. Although I put in a new K&N filter and washed the Mass Air Sensor with electric cleaner, I replaced the IACV and I am sure that is what did the trick. I found a Motorcraft part from a local parts store for $47 and my truck runs nicely just like it used to.

Thanks again for the input.

 

[Skibum1989]

If you have starting/idling problems in the future, use Seafoam in your engine and in your gas tank. It is available at most part stores and gets rid of the crap built up in your engine, as well as water in the tank. Fixed my idle and hard starts like magic.