Replaced front O2, immediate misfires, high trim. Diagnostic help? Topic is solved

[Vova585]

If you want to try it yourself get this one.

https://www.amazon.com/dp/B0BSH2XS4R?li ... ics_f_asin

$69 https://www.amazon.com/dp/B07JVT1NG2 I have this one, it works.

Does that one require to have external air compressor and pressure regulator? I like the one above since it had built in pump and can be portable. Sure not as much "smoke" delivery as OTC or harbor freight icon or the one vtl suggested, but has its benefits depending on shop equipment and work setting

[vtl]

Does that one require to have external air compressor and pressure regulator? I like the one above since it had built in pump and can be portable. Sure not as much "smoke" delivery as OTC or harbor freight icon or the one vtl suggested, but has its benefits depending on shop equipment and work setting

Yes. I have two compressors

[leapdragon]

Still toying with whether I want to do this myself or not. Somehow timing belts and CV axles and PCV service and quick struts intimidate me less than wiring harnesses and vacuum leaks.

But I do think it makes sense to get ahold of a no compressor smoke tester (I don't have a compressor either, my impact wrenches are all electric). I have ALMOST done it several times.

Meanwhile, I dragged the VIDA laptop back out and hooked it up to see if there was anything there that's not there with a regular scanner. To be honest I sort of hate using VIDA, it's ugly and slow and unpredictable. At first I FREAKED OUT at the list of codes lighting up like a Christmas tree but then I remembered that yellow = past code and that:

- Head unit was replaced with aftermarket
- Thus parking assist and AUM are angry because head unit is missing
- Since I last scanned I have remedied door latches, tailgate latches, child locking system, other items

So once I calmed down the only one that stands out is orange/current: ECM-121D, MAF signal too low

It seems incredibly unlikely that somehow my MAF decided to die exactly when i replaced the front O2 A/F sensor. But would a vacuum leak somehow cause the car to decide to throw an MAF code? Car was driving perfectly before I decided to do this preventative sensor replacement and I had no codes and average fuel economy, so I doubt the MAF has been bad all along...

Any thoughts about how the MAF code plays into all of this?

[vtl]

That's exactly how vacuum leak shows itself up: MAF starts to read less air than really enters the engine (and the engine knows it).

[leapdragon]

Ah! So this is just P0101. Got it.

[jonesg]

I used this mnual; transfer pump, stick a cigarette in the top inlet, connect the bottom outlet to the intake manifold and start pumping.
https://www.amazon.com/HORUSDY-Multi-Us ... 168&sr=8-6

[Vova585]

I used this mnual; transfer pump, stick a cigarette in the top inlet, connect the bottom outlet to the intake manifold and start pumping.
https://www.amazon.com/HORUSDY-Multi-Us ... 168&sr=8-6

Well I see problem with that. You will have to buy a pack of cigarettes and maybe use 2-3...then you will find the leak and will decide to celebrate it with a cold beer...and then you discover that you have 17 unused cigarettes...for some of us who quit it might be a tough challenge

[leapdragon]

Ordered smoke tester, should be here tomorrow afternoon.

Questions for all:

- Any thoughts on best place/port to inject "smoke"?
- Also, how concerned should I be about fouling the MAF sensor by blowing "smoke" into the turbo inlet pipe?
- Possible that my tightening the O2 sensor actually cracked the exhaust manifold loose or something and that's where the air is coming from?

The thing that keeps me confused is that the little things don't match here.

- Stepping on the throttle didn't cause the running to smooth out, it led to misfire codes
- Also, when stepping on the throttle, the short-term fuel trim stayed pegged to max

I would expect that for any non-obvious vacuum leak, adding throttle would smooth it out, and also cause short terms to fall at least a little, yet here we are and I've had eyes and hands all over all that stuff and can't see where the leak might be.

Any other brainstorms while I wait for smoke tester?

[vtl]

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[vtl]

Do a throttle swipe test, since you have VIDA. Bosch is not known for premature death, but still can happen.