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Old 05-22-2004, 06:55 PM   #1
Pi7467mp
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Default P0170 CEL How do I get rid of it?

Ok so what causes this code? And How do I fix it? I did a search and everyone said what they thought it was, and how they thought they might fix it, but not exactly what it is and exactly how to fix it. Help!!!
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Old 05-22-2004, 09:13 PM   #2
kastle
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P0170 Fuel Trim Malfunction (Bank 1)
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Old 05-22-2004, 11:43 PM   #3
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Short explanation:
Which means that your o2 sensor is not able to correct the fuel within its parameters, usually about a consistant +/- 20%.

Probably means poorly tuned engine managment, or failing O2 sensor.


Longer Explanation:
Your stock ECU has a fuel curve that is not only based on TPS, MAP and RPM, but it also considers Air temperature, altitude, engine temperature, and such. It does this mostly based off the 02 sensor.

The ECU will burn fuel based off of its stock map. The exhaust will pass the o2 sensor, and it will send out a voltage. This voltage will help the ECU figure out if its running to rich or lean. From here it compensates.

Example:
on a cold day, the air will be denser, so for a split second the engine will run a tad lean. the o2 sensor will see this, and the ECU will correct it. This is called Fuel Trim.

The ECU is allowd to correct fuel trim up to 20% before it throws a CEL.

SO, if you are using a piggy back to compensate for larger injectors and turbo, then the 02 sensor is having to work to far out of bounds. This will flag the CEL. If you used a scan tool, it would probably show that long or short term fuel trim is exceeding 20%. It may only be occuring when its cold outside, or when its warm, or only at a certain RPM, but the point is, its out of tune.

-Jake

Last edited by Unsung Boxer; 05-23-2004 at 12:00 AM.
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Old 05-23-2004, 12:24 PM   #4
Pi7467mp
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awesome. That helps me out a lot.. I do have a piggy back ( not for very much longer) and It is only tuned, by seat of the pants, not with a wide band. IO have a narrow band, but it is a piece of crap, and I basically have it there so my dash doesn't look so bare. I think this week, I am going to borrow a wide band and tune it.. anyway. Thanks again.
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Old 05-25-2004, 04:22 PM   #5
Sidwindr
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if the rear o2 sensor went bad would you get a faulty TPS sensor code as well as a hesitation at differing throttle posistions and tip in? i have a problem with both, and my cel scan told me i had a bad rear o2 and a faulty tps that wasnt reading correctly
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Old 05-25-2004, 04:53 PM   #6
Pi7467mp
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I do have weird throttle hesitation, and tip in hesitation too.. Im not throwing a code for anything anymore, I tuned w/ a wide band, but now my car is running like crap.. the stock ecu doesn't like me mesing with the fuel at all...
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Old 05-25-2004, 11:33 PM   #7
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the ECU has no idea what you are doing with the fuel. it is simply putting the reading it gets from the MAF/MAP sensor and putting it in the equation.

If you are getting hesitation, it is certainly a sign that you are too rich or lean.

-Jake
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Old 05-25-2004, 11:38 PM   #8
Pi7467mp
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whats weird is that i am right around 14.7 a/f, and I am around 11.5 a/f under boost.. before my fuel readinds were way out of whack.... I wonder if the LM-1 wideband I was using needed to be recalibrated or something? who knows.
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Old 05-28-2004, 09:50 PM   #9
dubRexn
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My friends car is throwing this, and all he has is a tb exhaust with the cel fix in the downpipe. he also has an injen intake, but stock everything else? Whats the fix?
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Old 05-29-2004, 10:53 AM   #10
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if that is all that he has done to his car, the he will most likely need to buy a new front o2 sensor. if you go to a dealer they are 120 bucks, but if you go to subaruparts.com i think they are $75+7 dollars shipping. Yesterday I was sitting in my car with my stereo muted, and I was like " my exhust has a lot of bass to it.." so I went to my trunk to get out a tool, and my sub woofer was pounding out bass.. I went back inside my car and I turned off my stereo so it would shut off my amp, and boom! my cel went off, and my car ran 1000 times better.. I looked in my engine bay, and the power cable for my amp, was arcing to my strut tower, causing my sensor to get odd readings.. well, at least I think thats what it was doing... I re did the power cable, and haven't any problems since..I know this seems strange, but hey... it worked.
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Old 05-29-2004, 11:47 AM   #11
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no thats not strange. Any short to ground can backfeed circuits. This is a major cause of false CEL's. If it all works good now, dont worry about it.

-Jake
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Old 05-29-2004, 02:22 PM   #12
White 2.5rs
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so for tuning should i have 2 bungs in my DP? one for the wideband and one for the factory 02?
also do i need my rear sensor?
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Old 05-29-2004, 02:25 PM   #13
Pi7467mp
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If you don't want to throw a cel, then you need your rear sensor. Im not sure how anyone else has their o2 sensors hooked up, but I have my factory o2 sensor in my up-pipe, and I have my wideband, in my down pipe.
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Old 05-29-2004, 02:54 PM   #14
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r u scared of it breaking up in the uppipe?
i dont care bout a cel my car will love cels especially w/ my fuel system all hacked
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Old 05-29-2004, 02:57 PM   #15
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umm... I never thought of it ever breaking it my exhaust.. that would seriously suck if it did.... I doubt it ever will.. knock on wood.
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