One recent day, our 98 Explorer (4.0L SOHC) required the gas pedal be pushed to start. After starting it would die if allowed to idle down on its own. The check engine light came on in the driveway during this time as well. (Prior to this day it had been idling a bit rough when sitting in park but it never died.)
I removed the mass air flow sensor and cleaned the wires with MAF sensor aerosol cleaner from the parts store. After cleaning, allowing to dry, and reinstalling, the explorer started right up with no need for the gas pedal. It also settled in at a nice steady idle around 700rmp or so. We ran it for a while. Shut it down and restarted several times and everything seemed to be fine. (I also disconnected & reconnected the battery. The CEL went away.)
Later that same day, it would not start again without the gas pedal being used (significantly). It now also dies immediately when the pedal is not used.
I removed the MAF and cleaned it again. No difference. I also then removed the IAC and cleaned it. No difference. I've looked all over to make sure there are no loose hoses.
Sure could use some help with ideas about what to do next. I'm considering buying a new MAF sensor and replacing it. Is it possible that after cleaning and running properly for a bit, the MAF could have gone bad altogether? (The CEL has not yet re-appeared, even after keeping it running in the driveway long enough to get it completely warmed up.)
Thanks for the replies, Roy & Medic. Here's an update. I figured you were on target about the IAC valve but I was unsure about spending $100+ on the part locally without being sure.
I had cleaned it once (as mentioned in the original post) but after a bit more research I got to thinking I might not have gotten it completely cleaned. What I ended up figuring out was that the moving part inside there was still a bit crusted up and actually stuck. After freeing it up carefully where it would actually move I cleaned it all out again w/ the electronics cleaner. I also removed the small black cap this time and took out the two small felt pads. I shook/tapped those out to get them as clean as I could without wetting them. Put everything back together after the chambers were good and dry and re-installed it on the Explorer.
It started up with nothing but the key turn on the first try. It idled smoothly, drove fine, and re-started multiple times thereafter without any problems. So far so good.
I'm sure the IAC could still stand to be replaced as it could fail again in the future, but this has at least bought me the time to shop around for the part at my convenience.
January, 3, 2013 AT 12:19 AM
IF YOU HAVE AN ADVANCE AUTO PARTS STORE ---THE 2ND LINK I GAVE YOU MAY SAVE YOU SOME $$$
I WAS BORED. SO I DID THIS
THERE WERE 3 --- IACs AVAILABLE----UP TO $103
JUST FOR GIGGLES---I WENT THRU THE PROCESS WITH THE LEAST EXPENSIVE ONE--AND MADE YOU A SCREENSHOT
THE ONE FOR $67, THE NEXT LEAST EXPENSIVE ("WELLS" PART # AC473), IN MY OPINION IS THE "BETTER ONE", IT HAS A LIFETIME WARRANTY. THE OTHER 2 HAVE A 1 YEAR
THEN WHATEVER ITEM YOU WOULD CHOOSE TO GET YOU "OVER $70" (MAXIMIZE THE POWER OF PROMO CODE A124)----WOULD ONLY HAVE TO BE $3 OR SO.
ONCE YOU PUT YOUR ZIP CODE IN--YOUR REGIONAL PRICES MAY VARY FROM MINE----ADJUST AS NEEDED TO GET OVER $70. OR WHATEVER ELSE YOU NEED ( A124
$10 off orders over $30, $25 off orders over $70, $40 off orders over $110. Online only. )
DO AS YOU WISH AS FAR AS WHAT YOU WANT
--- CHOOSE PICK IT UP AT THE STORE / PAY ONLINE/ PICK UP IN AN HOUR
PROMOS SOMETIMES EXPIRE----THE ADVANCE SITE WILL TELL YOU WHETHER THEY ARE GOOD OR NOT, WHEN YOU HIT "APPLY"---YOU MIGHT HAVE TO RUMMAGE THRU MORE ON A GOOGLE SEARCH TO FIND ANOTHER REAL GOOD ONE