yet another P0171 thread! woo!

[mazdaspeeeeed]

I have read just about every thread on the topic and tried everything i know of to fix this damn thing.

here is the list

-replaced EGR with brand new one
-replaced waste gate with a forge
-replaced ALL vacuum lines
-checked all connections on all pipes and tightend things down
-replaced spark plugs
-replaced primary 02 sensor
-replaced MAF sensor
-replaced cracked manifold with a new stocker
-installed FMIC with all 2.5" pipes and relocated MAF. all pipes are very secure and no leaks.

im out of ideas... the car used to have a real bad rough idle but that has been fixed now. the only thing in notice with the car now is on full throttle it will buck a little bit. occasionally the rpms will drop slightly and then come back up to normal....

I have reset the battery by disconneting the negative and pumping the brakes but the code keeps coming back...

 

[mazdaspeeeeed]

annyyyybody out there know a lot about this issue?

 

[magnumP5]

Injectors. Check the little grommets and rubber seals around the injectors for cracking, missing parts, etc. When I replaced my fuel rail last year I was intermittantly throwing P0171. I checked the injector seals and sure enough, one of them was broken. I ended up replacing all four seals and grommets and everything was fine.

 

[mazdaspeeeeed]

Injectors. Check the little grommets and rubber seals around the injectors for cracking, missing parts, etc. When I replaced my fuel rail last year I was intermittantly throwing P0171. I checked the injector seals and sure enough, one of them was broken. I ended up replacing all four seals and grommets and everything was fine.

will do. im guessing napa will sell those as well. thanks man

 

[sprinter119]

same code i was getting for like 4 months i dont knowwhat i did to make it go away. I took off my crankcase breather and hooked my intake back up and threw the supermap on my split second and the code went away. I did everything you did i had two mafs and two 02 sensorsit just went away i was thinking maype it was from the cold i dont k now

 

[mazdaspeeeeed]

same code i was getting for like 4 months i dont knowwhat i did to make it go away. I took off my crankcase breather and hooked my intake back up and threw the supermap on my split second and the code went away. I did everything you did i had two mafs and two 02 sensorsit just went away i was thinking maype it was from the cold i dont k now

damn code... i havn't checked my injectors yet but as soon as i get time (this weekend) i will do so!

 

[sprinter119]

yea i didnt even check mine. but i figured if it wre my injectors i would have driveability issues. even though it hasnt come back on in like 3 weeks i will probably still get them checked out. I think JNAOTO has had the code as well and said it just went away.

 

[mazdaspeeeeed]

if this doesnt work i will probably take it to my mechanic and pay the 50 bucks for a diagnosis...

 

[lyserjic]

Might be worth pulling the fuel pump. I had a constant P0171 that went away for good when the pump was replaced.

See my post on it here: http://www.mazdas247.com/forum/showpost.php?p=4331183&postcount=6

 

[mazdaspeeeeed]

Might be worth pulling the fuel pump. I had a constant P0171 that went away for good when the pump was replaced.

See my post on it here: http://www.mazdas247.com/forum/showpost.php?p=4331183&postcount=6

very useful. how much did the new stuff cost you?

 

[lyserjic]

Pump was about $120 if I remember correctly.

 

[mazdaspeeeeed]

so my car did something weird last night. I got home from work around 530 and at about 7:30 i went out to move my car and it started up fine but then almost stalled. I caught it just before it stalled by reving it up a bit.

So i pulled the car back into the driveway and let it stall... started it up again and it stalled right away... started it up again and everything was perfect and normal and this morning it drove perfect as well... do you think this is the same p0171 problem?

 

[mazdaspeeeeed]

annnybody have any suggestions to my last post?

 

[Geezer000]

For the near stall issue try the connector for the TPS (throttle position sensor cylinder looking thing on top of throttle body). Mine would idle like crap but when you rev it was fine and then through a code (don't know the number). As soon as you let off it would drop to low and stall. Even though the connector was clicked together it still didn't make a good connection and would intermittently cause the issue. All I did was disconnect it and spray contact cleaner and all good. When it happens I idle at about 100-200rpm. It's just sick how low these cars can idle with a good ignition.
Hope that helps.

 

[mazdaspeeeeed]

For the near stall issue try the connector for the TPS (throttle position sensor). Mine would idle like crap but when you rev it was fine and then through a code (don't know the number). As soon as you let off it would drop to low and stall. Even though the connector was clicked together it still didn't make a good connection and would intermittently cause the issue. All I did was disconnect it and spray contact cleaner and all good. When it happens I idle at about 100-200rpm. It's just sick how low these cars can idle with a good ignition.
Hope that helps.

where is the TPS located? I am guessing somewhere close to the TB but i wouldnt know what to look for exactly.

 

[Geezer000]

I think its the TPS. Its the cylindrical looking thing on top of the throttle body

 

[slavrenz]

I think its the TPS. Its the cylindrical looking thing on top of the throttle body

No - that is wrong. The cylinder looking thing on top of the throttle body is your idle air control valve. The TPS is black and is on the side of the throttle body towards the front, held in by 2 screws.

As far as your P0171 issue, here are the possible causes from the workshop manual:

- Misfire (you didn't say how your wires and ignition coils are)
- HO2S (front) deterioration
- HO2S (front) heater malfunction
- PRC solenoid valve malfunction
- Pressure regulator malfunction
- Fuel pump malfunction
- Fuel filter clogged or restricted
- Fuel leakage on fuel line from fuel delivery pipe and fuel pump
- Fuel return hose clogged
- Leakage from exhaust system
- Purge solenoid valve malfunction
-Purge solenoid hoses improper connection
- Insufficient compression

I've bolded the ones that you have not eliminated (based on your post), so those may be the next things to check. Honestly though, it sounds like you might have a clogged fuel filter or a pump that is going bad.

 

[Geezer000]

Thats it, IAC. Thats were my problem was. My connector was bad causing idle issues.

No - that is wrong. The cylinder looking thing on top of the throttle body is your idle air control valve. The TPS is black and is on the side of the throttle body towards the front, held in by 2 screws.

As far as your P0171 issue, here are the possible causes from the workshop manual:

- Misfire (you didn't say how your wires and ignition coils are)
- HO2S (front) deterioration
- HO2S (front) heater malfunction
- PRC solenoid valve malfunction
- Pressure regulator malfunction
- Fuel pump malfunction
- Fuel filter clogged or restricted
- Fuel leakage on fuel line from fuel delivery pipe and fuel pump
- Fuel return hose clogged
- Leakage from exhaust system
- Purge solenoid valve malfunction
-Purge solenoid hoses improper connection
- Insufficient compression

I've bolded the ones that you have not eliminated (based on your post), so those may be the next things to check. Honestly though, it sounds like you might have a clogged fuel filter or a pump that is going bad.

 

[mazdaspeeeeed]

I will clean the IAC and see if that helps. I was thinking of replacing my coil packs and wires anyway since the previous owner installed them and judging his work on the car i would say he went half assed on them as well.

when i was installing the prim 02 sensor i noticed that the connection piece that you clip on was melted a little bit (on the harness side). it didnt reach the medal part of the connector so i didnt think that this would be an issue.

No - that is wrong. The cylinder looking thing on top of the throttle body is your idle air control valve. The TPS is black and is on the side of the throttle body towards the front, held in by 2 screws.

As far as your P0171 issue, here are the possible causes from the workshop manual:

- Misfire (you didn't say how your wires and ignition coils are)
- HO2S (front) deterioration
- HO2S (front) heater malfunction
- PRC solenoid valve malfunction
- Pressure regulator malfunction
- Fuel pump malfunction
- Fuel filter clogged or restricted
- Fuel leakage on fuel line from fuel delivery pipe and fuel pump
- Fuel return hose clogged
- Leakage from exhaust system
- Purge solenoid valve malfunction
-Purge solenoid hoses improper connection
- Insufficient compression

I've bolded the ones that you have not eliminated (based on your post), so those may be the next things to check. Honestly though, it sounds like you might have a clogged fuel filter or a pump that is going bad.

 

[mazdaspeeeeed]

went to my mechanic today to see what the f is causing this P0171 and it turns out there is no P0171 anymore lol. I was looking over his shoulder when he did the readings and I saw 2 different codes that i dont remember.

But he said that I basically have a bad 02 sensor from napa. the sensor isn't getting hot enough, or the plug is bad, or a fuse is bad.