2003 Sport Trac won't idle after starting

[Ryan Bradshaw]

I have a 2003 Sport Trac and I first noticed the issue about a month ago. It would be random...like once every week or two. Now it seems to do it every day. I can turn the ignition and it cranks but it won't stay running unless I give it a few pumps on the gas. If I don't give it any gas the idle will slowly drop until it dies, maybe not getting fuel.



If I get it cranked and it doesn't die, once the engine warms up I don't have any more issues with it cranking. I've been doing some reading that it might by the ECM or the IAC, but I'm not exactly sure since as soon as the engine is warm I have no issues at all. Any help or ideas would be appreciated. Thanks guys!

 

[Vic Sorlie]

How many miles on your Trac? I think most here with Gen1 experience will tell you to clean the IAC mechanism, for which there is guidance in Projects>Maintenance section of this site. As well as that you should start at the air box and work your way "up." Is engine air filter in great shape? If not, replace it. Next up is the MAF (mass airflow sensor) in the intake tube between air box and the throttle body. Clean it if it's dirty, but there's specific cleaner for that. While you're working on the IAC, clean the throttle body and plate. Replace the PCV valve. How are your spark plugs? Pull one or two from driver's side bank and examine. How many miles on your fuel filter? You're going to see a difference after the underhood stuff above, but if engine's still not running right you'll want to check for fuel supply issue.

 

[Yardsale]

Start with cleaning the IAC and report back.

 

[John G]

idle air control valve.



clean or replace.



ToddZ has a project on this site for cleaning.



Cleaning worked for me initially, but within a year the problem returned. Not fun when you're in traffic and you stall, so I replaced it. Replacing it had a much longer lasting benefit. I bought one three years ago from Rockauto.com for $51. Airtex/Wells brand. It still works.



About cleaning, you use carb cleaner spray and a rag. I found that it's hard to see if you're actually doing anything, when you try to clean it. My cleaning rag did not get visibly dirty. But if it works for you, great.



The part is very easy to get to. It's on the top of the engine. Easy to remove, easy to replace. The only hard part is determining if you are doing anything when you try to clean its insides.

 

[Ryan Bradshaw]

Ok, it seems like the consensus is the IAC, so I'll start with that. It has about 153000 miles on it...not sure if that makes a difference. Thanks for all of the input. I'll report back with an update.

 

[Vic Sorlie]

Yep, does make a difference. Plugs ever been changed? Pull a couple from driver's side (easiest to get to) and see what they look like. If your plugs are original equip, then they're way overdue for replacement. Same story for plug wires.

 

[Drew Lonker]

I just had the same thing happen to my 01ST today. Truck would start and die out after about 3 seconds. I had to give it gas when starting and it stayed on after that. Could this also cause vibration at stop lights? I just replaced my plugs FYI. Truck has 101000 on it

 

[Yardsale]

Yes. Clean the IAC.