P0171 and P0174 lean codes

[duca1991]

Hey again, i was reading it may be a faulty Purge Valve that could be causing it ? If i clear the code, it comes back generally when the car is idling for a long time, thats when the idle drops and corrects. very strange

 

[duca1991]

I also notice the LTFT rises mostly when the car is at idle, What would cause this?

 

[Magnum65]

Hey again, i was reading it may be a faulty Purge Valve that could be causing it ? If i clear the code, it comes back generally when the car is idling for a long time, thats when the idle drops and corrects. very strange

It's very frustrating trying to figure this out.
If LTFT increases with idle then probably vac leak. As others have stated, try removing the purge valve and tape hole in manifold. I'm going to try this again on the weekend and run engine for longer.
The electric vacuum pump is not in play due to a one way valve in the T piece that goes to the brake booster.
I'll let you know if I find out what my cars problem is.

 

[duca1991]

It's very frustrating trying to figure this out.
If LTFT increases with idle then probably vac leak. As others have stated, try removing the purge valve and tape hole in manifold. I'm going to try this again on the weekend and run engine for longer.
The electric vacuum pump is not in play due to a one way valve in the T piece that goes to the brake booster.
I'll let you know if I find out what my cars problem is.

Mate, i blocked it off and its fixed my LTFT by ALOT, bank 1 is now -5 % and bank 2 is roughly 2%

The idle is now smooth and i cannot tell that there is anything wrong with the car now.

As soon as i plugged the Purge valve back in, i gave the car a few revs up to 2k rpm then let off to idle and waited, the LTFT shot up to 20% after 20 seconds or so.

So bam, found my issue, hopefully this fixes your issue as well!!

 

[07GTS]

just monitor the STFT's they are instant so u wont have to wait for any LTFT's to change

 

[duca1991]

just monitor the STFT's they are instant so u wont have to wait for any LTFT's to change

Im not sure, all i know is the LTFT were within 5% margin to 0 when i blocked of manifold.
Soon as i put the purge valve back in, it wasnt long before the LTFT were playing up again, got up to 35%
I damn well hope once i put a new purge valve in it fixes the issue, fingers crossed

 

[Magnum65]

Mate, i blocked it off and its fixed my LTFT by ALOT, bank 1 is now -5 % and bank 2 is roughly 2%

The idle is now smooth and i cannot tell that there is anything wrong with the car now.

As soon as i plugged the Purge valve back in, i gave the car a few revs up to 2k rpm then let off to idle and waited, the LTFT shot up to 20% after 20 seconds or so.

So bam, found my issue, hopefully this fixes your issue as well!!

Good to hear you are back up and running.
Unfortunately it didn't work for me... I pulled the purge valve out of the manifold and taped the hole in the manifold etc. but no change, removed it and couldn't blow through it so probably OK.
Cleaned MAP, removed and cleaned throttle body. Now LTFT increases with revs which is what is was like a few weeks ago. Might be a few probs combined. TPS still reads around 20% at idle but assume that's OK.
Removing manifold tomorrow then checking plugs, coils, injectors (if I can find them) and fuel line etc. The engine light came on a day after it was serviced so may indicate something not done correctly, but back then it was intermittent now it's always lean. If all that checks out I may then replace the fuel pump.

 

[duca1991]

Good to hear you are back up and running.
Unfortunately it didn't work for me... I pulled the purge valve out of the manifold and taped the hole in the manifold etc. but no change, removed it and couldn't blow through it so probably OK.
Cleaned MAP, removed and cleaned throttle body. Now LTFT increases with revs which is what is was like a few weeks ago. Might be a few probs combined. TPS still reads around 20% at idle but assume that's OK.
Removing manifold tomorrow then checking plugs, coils, injectors (if I can find them) and fuel line etc. The engine light came on a day after it was serviced so may indicate something not done correctly, but back then it was intermittent now it's always lean. If all that checks out I may then replace the fuel pump.

I'm curious to your issue, it wouldn't of been surprised if we had the same issue as i have heard purge valves are common to fail.
Would really love to find out what you're issue is.
Does not being able to blow through the purge valve indicate a good valve?

 

[ivyssv]

Unfortunately they are different.

what is the engine number for both of your cars

 

[ivyssv]

prob just the fuel pump/ filter not feeding the engine enough fuel pressure