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Re: unplug AMM, idles but hunts, replaced AMM won't run Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Fri, 31 Oct 2008 13:27:33
In Reply to: unplug AMM, idles but hunts, replaced AMM won't run, sailfast, Fri, 31 Oct 2008 12:54:03 Members do not see ads below this line. - Help Keep This Site Online - Signup |
First, I assume you got the right part number AMMs. You didn't mention the year and engine, but AMMs vary over the years, and just because they fit doesn't mean they are the right ones.
OK, assuming you have the right AMM; how does the engine run off idle? Does it accelerate away from a stop once you give it gas? Does it cruse OK? How do the spark plugs look? Lean or rich? Timing OK?
When the AMM is disconnected, the ECU has to assume an airflow and schedule fuel accordingly. So to be safe, it sets a richer mixture. Your car runs good. So when the ECU actually does get airflow readings and the car stalls, it's probably too lean. that tells me that you probably have a vacuum leak in the system between the AMM and the throttle body, or in one of the hoses to the throttle body. How do the spark plugs look? Do they look lean?
The other possibility is the IAC - Idle Air controller. Again, with no AMM, the idle gets set higher by the ECU. But with the AMM, the IAC will operate in its usual position. IACs get sticky over time, and they can wear in the area where they always operate.
If the car seems to run fine off idle and can pull away from a stop with little or no hesitation, I'd check first for vacuum leaks. When you find one, keep looking; like mice, they come in packs. If that doesn't do it, I'd suspect the idle air controller.
What year, engine, other symptoms (when driving), things recently done or not done (maintenance)?
posted by 75.25.4...
, Fri, 31 Oct 2008 18:08:23, Fri, 31 Oct 2008 13:27:33 <-- Viewing This Message
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