Intermittent PO171 and P0174 CEL

So for the past 8 months or so I’ve had a check engine light run the code P0171 and P0174 (at the same time, however sometimes it’s only P0171 and other times it’s only P0174).

My symptoms are:
- Rough Idle
- ticking noise between 1500-3000rpm in any gear but 1st (not sure if related)

So far I have done:
- Replaced fuel pump/filter (OEM)
- Replaced all 4 O2 sensors (aftermarket Walker sensors)
- Cleaned the Throttle Body thoroughly and replaced the throttle body gasket
- Replaced spark plugs (OEM)
- Had new Walker Exhaust manifolds installed by a local exhaust shop
- Checked all vacuum lines and used a smoke machine, no leaks anywhere
- Replaced air intake manifold Gasket
- Replaced MAF sensor
- Changed engine air filter to a K&N air filter
- Dumped some fuel injector cleaner into the fuel tank


Other details:
- I’m running with only the front 2 Catalytic converters but all 4 O2 sensors are still present.
- I had a P0606 CEL code about a month before this code occurred (the engine still idled rough and made the ticking noise), but that code went away.
- When the engine is cold and I’ll be getting up to highway speeds, I can hear a water “swishing” noise behind the dash (not sure if related)
- I did a compression test, cylinders 5 and 6 were at about 180PSI when the rest were at 200.
- I’ve taken it to 3 different Toyota dealers in my city. All 3 of them advised me to change the O2 sensors to OEM ones and are adamant that that’s the solution. I don’t think it is but I’m not sure.


I haven’t tried the fuel injectors, but maybe that’s where I should go to next? Any ideas?

 

After all you've done, I'd be changing to OEM sensors. The last O2 sensors are in front of where you would have had the second set of cats, correct?

 

Correct

 

Looked into Walker a little and found a person on Amazon that had issues with the element inside twice, so maybe you got some bad ones. I'd try OEM as my next step.

 

Have you had any luck on your quest?

 

Nothing. Local Toyota dealer had my in truck for 2 weeks swapping parts with an 06 to find the problem. They finally concluded that they thought problem was the intake manifold plenum. I spent 600$ on that, and it made zero difference. They would not give me a refund and Toyota Canada would not refund me either after arguing with them for weeks. Not sure what to do anymore...

 

Im sorry to here that bro. Being as im struggling with codes myself I wish i could help. Maybe ask Torspd. He's quite knowledgeable.

 

I have been having the same issues the last few weeks as well. after i installed a new CAI and exhaust to replace my old one that was falling apart.

 

I had the water sloshing sound. Head gasket. The compression test told you with the 2 low cylinders.
Mine idled rough for a few seconds after sitting then smoothed out. Check the antifreeze.

 

Antifreeze?

 

Ummmm, ya. Swipe typing on the phone strikes again... Voice to text has even better f ups.