99 explorer idles rough at startup

Starting is rough, idles rough at startup and stalls until it is completely warmed up (takes about 10 minutes), check engine light on, exhaust smells rich. Can't find a vacume leak. Anybody have a clue??? Would greatly appreciate the input!!!

The first thing that I would do is to go to an auto parts store and have them read the stored diagnostic codes that are causing your "check engine" light to come on. Hopefully your problem will be a bad sensor that is causing the computer to set the fuel/air mixture too rich.

Good Luck!
4caster

Thank you for the advice. I called AutoZone and I guess its against California laws for autopart stores to do that. Yet another brick wall (they seem to be closing in on me these days ...... harhar). The smog shops I have called want $75.00 to read a code for me, I can buy a code reader for $120.00, maybe even cheaper on Ebay. Yep, that sounds about right.

Anymore ideas..................anyone?

Starting is rough, idles rough at startup and stalls until it is completely warmed up (takes about 10 minutes), check engine light on, exhaust smells rich. Can't find a vacume leak. Anybody have a clue??? Would greatly appreciate the input!!!

Try this link to another thread.
http://www.automotiveforums.com/vbulletin/showthread.php?t=78748
if this doesn't help you out try searching for Idle Air Control in this forum. I know a saw a thread where a guy posted pictures on how he fixed his problem.

First thing I would do is pull the plugs. Hope you don't have BOSCH in there. Look for any differences between the plugs and check the insulators just under the boot for cracks. A lot of work but cheap. I know they won't reset codes but have never heard that they won't read them. Too bad a code reader you buy won't work on your next car.

1996 and later model cars have the OBDII connectors. You can buy a code reader for about $149.00 at Kragens in California, it's not much cheaper on Ebay by time you pay shipping charges. Another place to check in HarborFreights.com, I saw a code reader there for $35.00, not a fancy one. OBDII is used on all new cars and you should be able to use the code reader on future cars. OBDII is not exclusive to Fords. So it's not a bad investment to buy one. You can charge your friends to read their codes.

The future is over for OBD-II Next vehicles are going to be CAN.

Boxcar301,

I just took my 98 Explorer into the dealer for the same problem. I had to hold the idle at 2000 rpms for about 5 minutes before it would idle in cold weather, otherwise it would stall. After it warmed up, it ran fine.

The dealer replaced the cam chain guide assembly under a silent recall and the truck runs great now. It took the dealer over a day to make the repair but I didn't pay a penny. The truck was purchased used from a Chevy dealership several months ago with no warranty, it currently has 84,000 miles on it.

Had the same problem with 2000 Sport, Auto Zone ran code-- came up too lean on banks 1 and 2. Also bad hesitation when tyring to pass, replaced plugs and wires and fuel filter--N/G. Finally saw a post on another site that said until the engine warms up it runs crappy, after warming up the heat expands the engine and all gaskets, sprayed throttle cleaner on intake manifolds and and engine raced up--BINGO-
replaced upper and lower manifold gaskets and runs perfect now. 4.0 sohc, Haynes says to take off valve covers for easier access, not needed, start to finish about 4 hours, blow out entire area with air before taking apart to prevent ant debris from going into valve ports.
Hope this helps.

I had about the same problem. Thought it was the cold weather. Took it to work when the check engine light came on and scaned it. Turns out the coolent temperature sensor needed to be replaced. $25
Runs better than ever. I had like 60,000 miles on it. (2000 sport)

I also have a 99 explorer sport. It runs awful and stalls when cold and I also notice the oil guage takes a sec to engage upon starting. Once it's warmed up it runs decent, however while idleing say at a light I hear a click, slight hesitation then engine resumes normal. This happens every 10 secs or so while at a stop. My mechanic can't figure it out. He replaced the IAC and I did the Mass Air Flo. He also cleaned some parts, plugs and wires look good he said. The check engine light is on and the computer has a lean fuel read on it. Once he reset the codes and it came back with nothing. Any ideas? I'm lost. BTW, I have like 138,000 on it. Other than this it seems tip top. I was trying to squeeze one more year out of it but I don't know now.

You will likely find that the Oxygen Sensor is either bad or broke. There is a heater in the sensor and they are known too crap out this in short tells the ECM that there is a problem and can make the truck run like junk. There is a fuse for this as well you could check it if it is blown replace it. If it blows right away than the heater in the sensor has shorted out. Replace the sensor that should fix you up. As for the code reader it is a good investment at any cost as there are so many crooks running shops that like to sell you parts that you really don't need. These shops give good shops a bad rap. If you charge your buddys $10 each time you use the reader it is paid for in no time :) . Good Luk Greg North of 60

Thanks Twistn! Tell me, would it make sense that when I unplug the Mass Air Flo it doesn't stall? That's baffling me. Also, would the oil guage stick? Everything else looks as you describe. Thanks again!