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hi, i picked up my son a car at auction and the drive back was an adventure.. its throwing a P0171 code.. running lean so my first guess because its running so bad is the pump, regulator or filter but ill do the normal tune up and vacuum leak diagnostic first.. was wonder the best way to tie into the fuel line to hook up a fuel pressure tester.. any ideas and help are appreciated.
 

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P0171 is misfring cyl 1, may be just plugs contact contaminated or oxidized, bad ignition coil, damaged wires, or dead plug.

To trouble shoot, swap the ignition coil from cyl 1 to 2. If you have P0172 then the fault is with the ignition coil. Clean it up, repair or replace.

If you still have P0171, then the fault is with plug or wire in cyl 1. clean, repair or replace it.


hi, i picked up my son a car at auction and the drive back was an adventure.. its throwing a P0171 code.. running lean so my first guess because its running so bad is the pump, regulator or filter but ill do the normal tune up and vacuum leak diagnostic first.. was wonder the best way to tie into the fuel line to hook up a fuel pressure tester.. any ideas and help are appreciated.
 

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PO301 is misfiring of cylinder 1, PO171 is running lean.
Fuel supply likely issue, fuel pressure test requires special fitting for Celica.
I changed my fuel filter and it was still an issue, so then I changed the fuel pressure requlator, both were inexpensive 45$ and 15$ and issue has since gone away.
 

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Sorry you are right.

P171 is engine lean.

Usually it's caused by a dirty or bad Mass Airflow Sensor. Best way is to swap in a known good MAF to see if that fix the problem. All Toyotas and Lexus use the same Denso MAF.

After install new MAF, disconnect the battery's negative terminal to reset MAF values and drive the car a while for the ECU to learn new MAF values.

If that does not fix the problem then there may be air leaks on hoses around the throttle body or the air filter box. All those little rubber hoses have to be properly connected. There may also be leaks and cracks on those hoses.


PO301 is misfiring of cylinder 1, PO171 is running lean.
Fuel supply likely issue, fuel pressure test requires special fitting for Celica.
I changed my fuel filter and it was still an issue, so then I changed the fuel pressure requlator, both were inexpensive 45$ and 15$ and issue has since gone away.
 
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