What causes PCV fails quickly?

[It_s-Me]

@asemaster

First you have an emissions NOx failure with very low HC, now you say you have a misfire, which would actually lower NOx but give sky-high HC. What’s going on with this car?

@Nevada_545

Look at the exhaust gas report, there is no misfire, no indication of low compression.
There is nothing wrong with the PCV valve, the OP is over-examining it.

If not a compression test, what should he do ?

[Nevada_545]

Replace the catalytic converter. The reason the vehicle failed the emissions test was for high oxides of nitrogen, the PCV valve was a side track.

[asemaster]

@It_s_Me

If not a compression test, what should he do ?

Well in regards to the failed emissions test he should replace the catalyst. As far as the PCV valve goes, I doubt he needs to do anything with it, and it will certainly not cause a high NOx reading.

As a professional mechanic I rarely do compression tests. There are easier ways to get just as much or more relevant information.

[sciconf]

I took PCV that is no longer rattling - I was able to blow air from engine side. Secondly, I took a safety pin and able push the plate from engine side - its spring action confirms it is functional. So rattling gone away has no effect. But the link below states:
https://dannysengineportal.com/pcv-valve-how-does-it-work-failure-signs-ways-to-test-the-system/

Likewise, If the PCV valve gets stuck open, or a system hose gets disconnected or ruptured; producing a vacuum leak; you’ll notice one or more of these symptoms:

• Engine misfires at idle*
• Lean air-fuel mixture*
• Presence of engine oil in PCV valve or hose (I saw it on the manifold side)
  …*

All the above happening to mine as far as I know - lean fuel is because LTFT is from 4.6 to 6.8.

I would like think vacuum leak is going on - but needs to be verified.

I do not see any unusual smoke, but gas smell when I first start (either on engine and mostly on the exhaust). I never had to top up engine oil - its nearly getting closer to the year mark with 4k on it. I want to change it now but it needs to be towed.

[circuitsmith]

@sciconf

lean fuel is because LTFT is from 4.6 to 6.8.

No.
E10 gas can shift LTFT about 3 points.
If it were actually lean LTFT would be 25% or more and the O2 numbers in the emission test would not be zero.

@sciconf

temp difference of at least 198 making me to rule out CAT.

The cat is oxidizing CO and HC, which generate heat.
That does not prove that it is still de-oxidizing NO, which is done in a separate part of a 3-way cat converter.

I’m confused. You say it’s misfiring in the other thread, but the emissions test would show sky high HC if that were the case.

Have you checked to see the PCV valve is actually getting strong vacuum?
Run the engine with the valve detached from the valve cover and check with your thumb.

[sciconf]

@circuitsmith

No.
E10 gas can shift LTFT about 3 points.
If it were actually lean LTFT would be 25% or more and the O2 numbers in the emission test would not be zero.

@sciconf

temp difference of at least 198 making me to rule out CAT.

The cat is oxidizing CO and HC, which generate heat.
That does not prove that it is still de-oxidizing NO, which is done in a separate part of a 3-way cat converter.

I’m confused. You say it’s misfiring in the other thread, but the emissions test would show sky high HC if that were the case.

Have you checked to see the PCV valve is actually getting strong vacuum?
Run the engine with the valve detached from the valve cover and check with your thumb.

Thanks @circuitsmith - here are the details:

1. Fuel Trim
   LTFT + STFT > 4.68 + 7.68 >= 12.36

2. Misfire
   Misfire started after the emission testing
   It started soon after I reset the PCM/ECU by disconnecting the battery for 5-10 mins

Later another day, I let the capacitors to discharge completely - it slowly started up learned everything - no misfire. I didn’t turn off the car for 3-4 hrs. LTFT slowly rose from 0 to 4.68 to help maintain the idle (which slowly increased to 800). See photo. Took it to the freeway and drove at 4k on D3. I thought the problem solved. But after re-fulfilling with 91 gas (usually 87) it came back.

3. …PCV valve is actually getting strong vacuum?
   I will repeat this test today. It was doing it.
   Again, after driving the car, I saw oil (soaked) on the manifold side of the PCV

4. Vacuum leak, Fuel pressure/leak are likely cause ?
   Even before misfire, I was smelling gas from exhaust

I am trying to test for Vacuum leak - I like the smoke method since it gives better clarity. I never done this before. Will talk to part store for any …

[sciconf]

Thanks @asemaster
What is the best way to conduct vacuum leak test?
I never did it before.

NGK plat spark that came out of the car - replaced with new NGKplat:

[sciconf]

@circuitsmith

Have you checked to see the PCV valve is actually getting strong vacuum?
Run the engine with the valve detached from the valve cover and check with your thumb.

I did this test right after cold starting the car:

• there is a definite pull on my thumb
• it is not a strong pull that I experienced on a warm car when I tried to test the O2 sensor.

I think its working - a mechanic told me that he has seen many PCVs without rattle sound but were working - I didn’t believe him then.

The PCV came off the car, I soaked it in some spirit - I hear some movement but not the same rattle.

I also checked for vacuum leak by spraying throttle body cleaner. My kid confirmed movement on the rpm around the throttle body gasket a couple of times. I went back 4hrs later to repeat the test on the exact spot and to film it. But this time no change in rpm!

This gasket is made of paper. I do not know if the gasket is deformed during the 2nd test. CEL is still flashing (didn’t clear it from the morning).