01 Job One starts fine, won't idle

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John Turner 3

John Turner 3

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Hi -



I've gotten great help here in the past (thanks, Cayman!) so I am hoping someone can point me in the right direction for this new problem.



01 Job One Sport Trac, 103,500 miles, engine rebuilt by dealer at 99K (new timing chains, all four, all new tensioners/guides, new manifold gaskets). No problems, pleased with dealer's work, would drive the truck anywhere.



Last night, popped out for a quick trip to the bank and the post office. No problems. This morning, went to go to work, and the truck starts up just fine but will not idle at all. No warning lights, no check engine light. Starts right up (no clicking or hesitation), but as soon as I take my foot off the gas, it dies right away, doesn't even try to idle.



All accessories work (radio, A/C, etc). As I said, starts right up.



Any ideas? I have one of those OBD code reader thingies...would I get any info from that even if the check engine light is not on?



I am hoping it is something I can fix...I'm pretty handy, as long as it doesn't involve taking the engine apart I can probably handle the repair.



Any help is appreciated, I'm stumped. Thanks in advance,



John



 
Last edited by a moderator:
if the CEL is not on chances are there is no code in the computer....



I would start by taking a look at all the vacuum lines and basic electrical connections...



Could clean the IAC valve....



Does it go away when it warms up, or that doesn't make a difference ???



Todd Z
 
Hi Todd -



Not sure about the warming up part...what's the definition of warmed up? I did run it with my foot on the gas (at about 2500rpm) until the thermostat opened up, but that didn't seem to have an effect. It still dies as soon as I let up on the gas.



John

 
Yup, that would be warmed up....



Sounds like something may have come loose or fell off......



Check the basic connections, TPS, MAF, intake hose,,,stuff like that..



Todd Z
 
Hi -



Just took a good look....did not see anything loose or disconnected. But, I am not all that sure where to look, as I don't exactly know what the TPS, MAF, etc is. But every connector I can see is connected., and I don't see any loose hose ends.



Is there a good picture somewhere of the components like IAC, etc? I can pick out the basics, alternator, etc but a lot of the stuff I see all looks the same.



Caymen, would bad plug wires only show up on idle, and not start? When it starts, and if I keep my foot on the gas, even at low rpm (like 1200), the engine sounds exactly like it should.



I am stumped...at idle speed (with my foot on the gas around 1000-1200rpm) it sounds absolutely fine...it just won't idle on its own.



John

 
Just having the engine rebuilt, it could be anything?



The most common problem with the ST when it starts but won't idle is a bad/dirty IAC valve (Idle Air Control valve). When your throttle is closed, the IAC allows a metered amount of air to by-pass the closed buterfly valve on the throttlebody.



The dealer may have rebuilt the engine internals, but they usually just put the same external parts and accesories on. So your IAC may have over 100K miles on it, os it may be way past due for a cleaning or may even need to be replaced.



...Rich
 
Just having the engine rebuilt, it could be anything?



The most common problem with the ST when it starts but won't idle is a bad/dirty IAC valve (Idle Air Control valve). When your throttle is closed, the IAC allows a metered amount of air to by-pass the closed buterfly valve on the throttlebody.



The dealer may have rebuilt the engine internals, but they usually just put the same external parts and accesories on. So your IAC may have over 100K miles on it, os it may be way past due for a cleaning or may even need to be replaced.



...Rich
 
I had a similar problem when I got my '01..Had about 80k at the time..It would die as soon as I let off the gas.. I had just bought it about a week earlier so Carmax sent out a towtruck, They replaced the IAC.. ran like a champ again..



My vote is the IAC...
 
Thanks for the replies, everyone.



Rich, where is the IAC? I googled it, but the engine they're showing doesn't look like my engine at all.



I see in the Projects section that Todd Z posted a "Cleaning the IAC motor" project...is that what I should take a look at?



John

 
Yeah John.. that should give you a good look at it. Also search cracked elbow and see if you can locate this hose to mark this off the list of possible issues.. But again, sounds like the IAC to me..
 
John, Since you have a job 1 the IAC is a little different then the project I wrote, but it is the same principal....



Since you have the mileage you do on the IAC, since I am sure they did not replace it, I would say clean it first, BUT I would recommend you replace i if the cleaning fixes it..



Todd Z
 
Thanks for the replies everyone. Problem resolved. It was a stuck IAC.



I pulled it off and cleaned it up, then used a pair of needlenose pliers to work the valve because I couldn't get a grip in there with my ginormous fingers. While working the valve with the pliers I squirted more cleaner in there.



Todd, you are right, it looked a little different than the one in your project but it was close enough that I knew I was on the right track.



Truck idles fine now...I will stop at the dealer on the way in to work and get a new IAC...the old one is still pretty dirty and replacing it will just take a few minutes.



Thanks again to everyone...if I hadn't known where to look, I would have had to take it to the dealer and spend (relatively) big bucks. I don't mind doing it if I have to, but for simple fixes doing it myself is much more fun!



John

 
Welcome........;)
 

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