ACT/ECT

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Jun 6, 2000 | 02:12 PM

Guy

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Joined: Mar 2000

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ACT/ECT

Hi everyone,I'm curious as to why the computer sets codes 21 and 24 only on long extended trips. Imade a 600mi return trip a few weeks ago and the check engine light was intermittent. Would come on every 30-50 miles and shut off for same distance and on and off and so on... I know what the book says on these codes, I've checked them at different temperatures and crossed referenced them with the info at this link (http://www.iaw.com/~aubertin/88mgt/eec-iv/ectact.htm) and the readings I get are really close. I used a heat gun to warm up the act sensor. These codes do not come it when driving around town or short trips(80mi). I really have no idea what I should or can do about this. Can this have something to do with the truck being hard on gas and lack horse power? It's pretty frustrating when the sensors check out ok but the computer is telling you otherwise. Thanks for your help

Guy

'92 F150 XL 4x4, 5.0L AOD, Headers, K&N Air Filter, 3.55 Gears, 31x10.5x15 Tires.

Jun 7, 2000 | 07:43 AM

PAUL_2

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Joined: Jul 1999

Posts: 3,172

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ACT/ECT

Guy ,
These two sensors control the engines fuel/air mixture. First ensure the coolant level is at its proper level an its quality is Ok . Does the engine run hot ? The best way to test these sensors is installed on the engine . If on extended trips one of these sensors goes out of its operating range , it will cause the check engine light to come on . Possible causes are : Low coolant level , outside air temp is below 50F (ACT) , faulty connections or sensor(s)
Paul