Corolla 2000 Engine Light - Toyota Corolla, Chevy Prizm (1998-2008)

My corrolla 2000 engine light went on.

I got a PO171 on the OBD II reader. The car is drivable, but there is a lag when you accelerate from a stop or when moving( unless you give it alot of throttle it will stall when accelerating from a stop ). It also is hard to start when hot , but if you open throttle all the way and cranck for 5 seconds and then do a regular start it will start fine, but the exhast smells very rich for a minute.I dont know if the hard starting is related to the PO171 code or another problem itself.

I checked the induction system,heated oxygen sensor,mass air flow meter, ignition and exhast system and all seem to be fine. I have not checked the fuel preasure,injectors,or ECM. I checked the easy ones first.

Am I on the right track here? Am I missing anything?

Is there a easy/ cheaper way to check my fuel presure than buying a SST preasure set up ( very expensive) from toyota?

Thanks, Sam

Unfortunately - there is no easy way to check the fuel pressure on a 1ZZ-FE engine on the US spec'd Corollas (1998+). You can try to fashion something up that resembles the Toyota special service tool - but may just be easier to buy or borrow one, if you can.

PO171 (system trim too lean -> air fuel mix is overly rich) is a common code for the Corolla for some reason. I got that several times in the first 30K miles of my 2002. Based on your post - you have just about covered all the "easy" stuff and the most commonly fouled components (MAF, O2 sensor).

Other than checking for obstructions in the intake and exhaust and a plugged air filter - might try to "clean" MAF. Even if it looks OK, cleaning the IAT sensor on the side and the two sensor wires inside the body can help. Good site here for procedure:

http://spydermagazine.com/2002/March/maf_clean/maf_clean.htm

If using a K&N filter or equivalent - make sure that the filter is not overly soaked with oil. Double check the plugs and check and see if the gap has closed on you.

Sometimes one of the switching valves in the fuel pump/filter/regulator unit in the tank will lock up - causing the system to run rich. The VSV in the induction system will sometimes get stuck and cause a rich condition as well.

The chance that it is a fuel pressure related problem is remote - unless you think the fuel pump is going out (low probability). ECM is also pretty bullet-proof. Injectors - maybe. The earlier Corollas had some problems with the solenoids in the injectors freezing up - where the ECM couldn't vary the duty cycle (basically fully open all the time). Won't be able to tell for sure unless you have them flow tested on a bench machine.

Good Luck.

Thanks fishexpo, I will try cleaning the MAF first, and then go from there .I really appreciate the help.

Thanks again ,Sam

Unfortunately - there is no easy way to check the fuel pressure on a 1ZZ-FE engine on the US spec'd Corollas (1998+). You can try to fashion something up that resembles the Toyota special service tool - but may just be easier to buy or borrow one, if you can.
PO171 (system trim too lean -> air fuel mix is overly rich) is a common code for the Corolla for some reason. I got that several times in the first 30K miles of my 2002. Based on your post - you have just about covered all the "easy" stuff and the most commonly fouled components (MAF, O2 sensor).
Other than checking for obstructions in the intake and exhaust and a plugged air filter - might try to "clean" MAF. Even if it looks OK, cleaning the IAT sensor on the side and the two sensor wires inside the body can help. Good site here for procedure:
http://spydermagazine.com/2002/March/maf_clean/maf_clean.htm
If using a K&N filter or equivalent - make sure that the filter is not overly soaked with oil. Double check the plugs and check and see if the gap has closed on you.
Sometimes one of the switching valves in the fuel pump/filter/regulator unit in the tank will lock up - causing the system to run rich. The VSV in the induction system will sometimes get stuck and cause a rich condition as well.
The chance that it is a fuel pressure related problem is remote - unless you think the fuel pump is going out (low probability). ECM is also pretty bullet-proof. Injectors - maybe. The earlier Corollas had some problems with the solenoids in the injectors freezing up - where the ECM couldn't vary the duty cycle (basically fully open all the time). Won't be able to tell for sure unless you have them flow tested on a bench machine.
Good Luck.

My mother has a 2001 Corolla and the check engine light came on. The OBDII scanner read as PO171. I cleaned the MAF sensor with brakleen and then disconnected the battery for 1 minute. The CEL then cleared but a few days later it came back on. This car has two O2 sensors. I asked my parts guy at the Toyota dealer what sensor does most buy and he told me the one in the exhaust manifold. Did any of you guys changed O2 sensors and if so which ones did you change?

Sometimes it takes more than one maf cleaning to work. Its not uncommon for the light to come back on after the first try. Make sure whatever you use doesnt have silicone in it.

How many miles does it have on it? If its around 100k I'd go ahead and change both the o2's.