an occasional starting problem.
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Senior User
Joined: May 2005
Posts: 128
Likes: 0
From: NEWTOWN, ct
an occasional starting problem.
I have a 99 250 5.4 with an automatic that i'd like to think I take good care of. Over the past year and a half or so, Ive experienced an issue where I've went to start the engine and it wouldn't hold an idle. It will just drop down to 0 RPM after about 3 seconds of running. If I restart it, it does the same thing UNLESS I manually hold it above 1200 RPM with the throttle. A few times it will return to normal idle after a few seconds, but sometimes (like 2 days ago after an 11 hr workday), I will hold it at 1000-1500 RPM until the engine has warmed up and it STILL idles down and putters out.
Any ideas? I know I could wantonly go changing valves and sensors, but I want to have a better idea of what it might be, and whats causing it. I'm open to suggestions.
Any ideas? I know I could wantonly go changing valves and sensors, but I want to have a better idea of what it might be, and whats causing it. I'm open to suggestions.
Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
First thing I would do is clean the IAC (idle air controller). It's a piston that allows air to bypass the throttlebody, if it is getting stuck it can allow too much or too little air. It's free (or at least the cost of a can of carb cleaner) and sounds like the problem.
More Turbo
Joined: Aug 2006
Posts: 530
Likes: 2
From: W. Wisc
I agree. The IAC is a common cause of dying at idle and cleaning it usually will fix it. I used to clean the IAC on my SHO every few years when it would start dying when coming to a stoplight approaching idle. Fixed it every time.
Just be casreful not to damage the seals with any sharp tools. Usually a toothbrush and carb cleaner are all you need.
Just be casreful not to damage the seals with any sharp tools. Usually a toothbrush and carb cleaner are all you need.
