Check Engine LIght


Old 08-28-04, 11:40 AM
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Join Date: Aug 2004
Posts: 12
Check Engine LIght

Hello, I have a questions regarding a Toyota Corolla 2000, 4 cylinder sedan. The problem is when I am driving at 50 mph or over the check engine light turns on. The entire car also begins to treble and it has a lack of power to pick up speed. We have already put in a fuel system cleaner. Also the OBD II shows a diagnostic code of PO171- System too lean. Do you know what this can be? Can it have something to do with oxygen sensor, even though this is suppose to have its own diagnostic code?
Thank you in advance for all your help with these questions.
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Old 08-28-04, 12:56 PM
Join Date: Dec 2001
Posts: 2,538
an faulty o2 could set that code but will usually have other o2 related codes stored also but it is unlikely that the o2 is bad based on your description, the engine is running lean and is likely why it has no power a fuel pressure test would be where I would recomend starting or possibly having the fuel filter changed first if you havent had it done within the last 30000 miles.
the fuel pressure test will need to be done while driving the car when it is acting up to determine if you are losing fuel pressure.
Old 08-28-04, 05:49 PM
nelson knowles
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Too lean can be cause by a number of things. So just dont go changing parts and sensors.
A question:When you slow under 50 mph does the vehicle drive normal?
Go some were on a back road and floor it from o to 60 and see at what point it lost power.
Old 08-29-04, 06:23 AM
Thread Starter
Join Date: Aug 2004
Posts: 12
When I'm driving under 50 mph it drives normal. It's usually when I am picking up speed that the car will start off real slow for a few seconds before actually going fast. That includes sometimes when I am picking up speed after standing at a red light. But it is usually when I am trying to go at high speeds like on the parkway or turnpike. Once the car picks up that speed there is no problem with the power, just the trembling.
Old 08-29-04, 07:49 AM
Join Date: Jun 2002
Location: Long Island, NY
Posts: 1,531
Agree with bejay, you need to test fuel pressure.

BTW: the fuel fiter is in the tank
Old 09-04-04, 03:48 PM
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Thumbs up toyota master & ase master

i agree with checking fuel pressure,you may want to also have some one look at your maf grams & your fuel trim long & short.odds are you will find that your maf is at fault.also look at the air intake temp.

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