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Discussion Starter · #1 ·
ok guys,
i know this topic has been covered many times, and ive searched on and on throughout the forums.

i have a stock 2000 gt, currently getting a CEL P0171 lean bank 1

i replaced the o2 sensor, and tested it, its working fine.

the MAF is as clean as it can be

and
there isnt any noticable vacuum leaks.

im out of ideas, anyone have any other ideas for me???

thanks in advance
PunkT
 

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MAF's can go bad.. And testing only shows if they are dead.. No likely.. but it's been know to be a problem..

O2 Sensor.. again not likely.. but has been known to be a problem..

Plugged injector.. Can be.. Most likely cause.. Send the Set to www.witchhunter.com.. and fo $100 you'll have them beack in a week.. I'm not affiliated with them but I like the Work..

Cap
 

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Does the car run normal besides having a CEL? Have you reset the light and had it come back on? Do you have an OBD II scan tool?
 

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Switch that cylinder's injector with one from another cylinder, and see if the error code moves in correspondence with the switch
 

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Discussion Starter · #6 ·
cap - yeah i was thinking it had to be the injectors because my MAF is running 1.28 g/s at idle, and goes up accordingly to the TP. the O2 sensor is showing proper voltage at idle and under load. do you recomend any of the injector cleaners?

chameleon- car runs fine, yes it has been reset many times, CEL comes back on after 30 miles, when the computer reconfigures. yes i have an open tune scan tool.

thanks guys for the info and ideas, much appreciated.
 

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Switch that cylinder's injector with one from another cylinder, and see if the error code moves in correspondence with the switch
That will only work with a Missfire.. The Code in Question is an Engine Code, not a Cylinder Code.. so that won't help..

Fuel Trims on the Toyota 1Z/2Z Engines normally run +- 5 on the Short.. and Anything lower than a +- 10 for the Long is Considered Normal..

Thye Larger Intakes on the Engines will force the Long Trim to go +10 to +15.. the +15 will ( Can ) cause a Lean Condition in WOT.. so be carefull.. Even if the Long is big.. the Short should still be +- 5..

Cap
 

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The main reason I was asking if you reset the CEL is because you are going to automatically get this if you ever run out of gas, and I wanted to be sure that you weren't chasing a ghost. It seems like you do know a thing or two about cars, though.

You have all the right ideas with things you have been trying. Not many people go beyond looking at their airbox and hoses when checking for vacuum leaks; did you check your intake manifold when looking for that? Maybe all this could be fixed with a new intake manifold gasket! Try spraying some carb cleaner around the perimeter of your manifold and see if that affects the engine idle, if you idle dips or surges its because it sucked some of the carb cleaner in through an area that it shouldn't have been able to. The best thing to do would be to just connect a vacuum gauge for diagnosis.

At this point, if we have no vacuum leaks, a MAF that checked out ok and O2 sensor that is brand new it would definitely point to a fuel issue. I would be most suspicious of the fuel injectors but its also possible that your trouble area could be your fuel pump, pressure regulator or fuel filer, so keep that in mind.



On a side note, I found it interesting that the "normal" long/short fuel trim value that evilthorne posted up was +/- 25% and the "normal" value in my paperback hard copy that was printed in 2000 says +/- 38%. I wonder why it changed over the years when compared to what it was when the 7th gen Celica very first came out. Better ECU? Better sensors?
 

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Discussion Starter · #9 ·
oh yeah its a brand new intake manifold and gasket too, forgot to mention that. the CEL has been the same before and after the manifold was switched out.

the only other symptom i could mention is at idle the rpms jump a little back and forth, not much but it does. it goes from 680 to 710 back and forth. other then that the car runs fine.

still cant find any vacuum leaks so i think its time to clean the injectors lol

thanks again for the ideas and help guys
 

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I had the same code. You more than likely are experiencing slow acceleration too. You may not notice it but once the problem is gone you will find your car to be much faster. Not a loooot but noticeably.

There are two parts to the MAF. The red drop looking thing and inside it two wires if you get a good angle and lighitng you can see. even if looking fine I'd go to autozone, buy some MAF cleaner for 5 bucks and spray the crap out of it. Then wait then spray some more. Then wait to dry for a while. Make sure you sprayed a lot. Then reinstall and try it. After resetting the ECU too to get rid of the light. Worked for me!
 

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I'm experiencing all the same symptoms for my 2000 celica gt. P0171 code. Slow acceleration. Changed the intake manifold gasket but that didn't resolve the p0171 code even after resetting the code. I will try to replace the maf sensor today. Ill update as to whether this took care of the problem. Thanks for everybody's input and experiences.
 

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Are you using the stock intake system or aftermarket?
I just purchased my 2000 celica gt so I'm guessing it is stock. I just chang the maf sensor yesterday and the cel light came back on again after I erased the p0171 code. So I feel like I'm back at square one again. But with the knowledge that the code is not caused by the intake manifold gasket or maf sensor.
I appreciate all the info from everybody on this site. All this is new to me and being a female this does not come natural to me. But I'm fixing my own car and learning along the way.
If anybody has a solution to my issues please respond. The main problem my car is having is the lack of acceleration I'm getting. I purchased the car in this condition thinking it would be an easy fix.
 

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Can you post a pic of the engine bay, please?
So I removed the maf sensor I bought from oreilleys and put the original toyota one back in because the new one was making my car run worse. I also changed the valve cover gasket and spark plugs. The cel has yet to come back on (fingers crossed). I'm going to have to remove the valve cover again though because I didn't use any gasket sealant at the time...I will also be installing new lift bolts at the same time. Thank you for the support. Im now dealing with lift bolts and a whole new set of inquiries ( as u can find in another thread I started) :love:
 

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I didn't use any gasket sealant at the time
If I remember correctly, there are only two spots on the cover that are called out for sealer. Definitely, not critical.
 

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It may be much later than the last message, but I believe it will help many like me.
For all those who have a problem with the P 0171 on Celica models like me and have tried to change the MAF, replace the O2 sensors and everything else, watch this video to fix the P 0171 error

It will save you time and maybe money if you haven't replaced everything before.
 

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Update...

so I finally figured out what was wrong. It was a crack in one of my fuel injectors.Once I changed this the code went away and everything is good.
 
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