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Jim Grant Tech Tips Jim Grant Tech Tips
A collection of helpful articles based on reader submissions
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  Jim Grant's Tech TipsJim Grant's Tech Tips
Below is a collection of Jim Grant's Tech Tips sorted by Vehicle Make. These Tech Tips were answers to questions submitted to Jim by ALLDATAdiy.com users over the course of many years.
If you have any questions, please feel free to email us.
 
 

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  Jim Grant's Tech Tips

'99 Subaru, Fuel Trim Malfunction

Q: I have ‘99 Subaru Forester and the check engine light has been coming on. I had it checked on the computer and it comes up as a fuel trim malfunction. Unfortunately it was not explained to me what is exactly wrong. Can you help? ...James

A: Fuel trim is a dressy word for how much adjusting the computer has to do to get the right amount of fuel to the engine. On today’s vehicles this information is reported as fuel trim. If the computer says, "hey I ran out of adjustment" it turns the check engine light on. Fuel trim problems come in two colors, either the engine is getting too much fuel or not enough fuel. In either case, if the computer can’t adjust for the variations it gets upset and turns the check engine light on. There are different computer codes for too much fuel and for not enough. If the shop that is servicing your vehicle cannot explain that much to you find another shop.

 
     
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