Need help breaking down these OBD2 readings

[marshallma0504]

Hello all, I have purchased my new catalytic converters and are waiting for them to show up. In the meantime I purchased an autel obd2 scanner and took some readings after clearing the P0430 code. I don’t know much but I do know that my fuel trims are not correct. I will post photos in 2 sections: idle and under load at 60mph. This is before a KAM reset as well.

Idle:



Under load (55-70mph at half throttle:

 

[marshallma0504]

The car drove fine no misfires or hiccups the only weird thing it does is if you rev it at idle when it comes back down it settles to 700 ish then drops to 500 then comes back up. So I’m no expert but it seems like my car is adding fuel to compensate for the downstream sensors reading poorly due to failed cats? I have no idea. Any feedback is appreciated.

 

[marshallma0504]

The spark advance was 2-4 at idle and went from 15-40 under load. I can’t read timing degrees live sadly.

 

[marshallma0504]

I’m thinking I need to do a KAM reset to really see my fuel trims improve. The cars trims are from 12 years of learning based on a stretching timing chain and now the engine is back to new timing spec. Also going to get some 93 in the tank to help with spark knock because I can hear it. I wish I knew more about how to use this scanner but I’m doing research now on it. And the fuel system is in closed loop mode

 

[SHOrod]

With fuel trims like those, on both banks, I'd be looking for a vacuum leak that would contribute to both banks, such as anywhere between the air filter and the intake manifold.

-Rod

 

[marshallma0504]

With fuel trims like those, on both banks, I'd be looking for a vacuum leak that would contribute to both banks, such as anywhere between the air filter and the intake manifold.

-Rod

Is it running too lean due to vacuum leak? I’m doing the KAM reset to see how it improves

 

[marshallma0504]

Is it running too lean due to vacuum leak? I’m doing the KAM reset to see how it improves

I did take off the throttle body and that’s the only gasket I didn’t replace. I also have a clamp on the CAC to throttle body pipe that won’t tighten down to the throttle body properly so I need a new clamp for that. It doesn’t come off when I pull on it but I can shimmy it side to side slightly. And it has oily residue around it so I probably need a new pipe. Thoughts?

 

[SHOrod]

My thought is the fuel trims are really high in the positive direction because the computer is increasing the fuel injector pulse to attempt to compensate for a lot of extra air. The hose to the BOV appears to not be properly seated. If you have access to a smoke tester, that might be the best way to find a vacuum leak if there is one.

-Rod

 

[kryptto]

I would suggest also removing the noise maker horn and capping the hole, that or buying a PI CAC pipe without that IMHO dumb horn thing. they have been known to leak too.

 

[marshallma0504]

I would suggest also removing the noise maker horn and capping the hole, that or buying a PI CAC pipe without that IMHO dumb horn thing. they have been known to leak too.

Yeah I have heard that those leak badly. I’ll measure the hole and go to the hardware store and buy a rubber cap like people do for the VTA mod and clamp it tightly.

 

[marshallma0504]

But other than the extra fuel no huge concerns? What could have caused the P0430 if the cats aren’t bad?

 

[marshallma0504]

Here’s my new idle readings after the KAM reset and 7 gallons of 93. It idled noticeably smoother and didn’t hesitate to go into 6th gear anymore. I used to have to coax it with the throttle. I drive her nice and easy but I did have a pending P0420 once I got home from 20 min or so of driving.

 

[marshallma0504]

@kryptto what are your thoughts?

 

[kryptto]

as far as the numbers in general I am. the wrong person to ask..... however the P0420 code is all about catalyst being bad, restrictive cats, pipes, resonator or mufflers physical closure. it also indicates bad heated O2 sensors, exhaust leaks around or before the sensors, like the exhaust manifold is leaking or otherwise, check the downstream o2s wiring make sure they don't show visible damage.

now my biggest take away is the possibility of misfire or leaking fuel injector. pull the plugs look for wet plugs. look for oiled up plugs as well.

the trims and all that IMHO are all post issue, so the system is compensating for something defective or not working properly to begin with.

if I am suggesting items u checked - I wasn't going back to read it all agaips - I would also be using Forscan, it has system testing as well and I know the info from it can be more informative.

HF2 CHECK FOR OTHER DTCS


Note:Internal deterioration of a catalytic converter is usually caused by abnormal engine operation upstream of the catalyst. Events that can produce higher than normal temperatures in the catalyst are particularly suspect. For example, misfiring can cause higher than normal catalyst operating temperatures.
Note:Make sure the customer has not noticed a high engine oil consumption. An engine that consumes oil at a high rate deposits high levels of phosphorus on the catalyst and reduces the catalyst efficiency.

 

[marshallma0504]

Yeah I checked all the plugs and regapped them they are dry with some carbon that I cleaned off lightly. I’m leaning towards failing cats due to the failed turbos and I had an exhaust leak as well as a vacuum leak from the intake pipes. Once I put the new cats on and make sure everything is snugged up both intake and exhaust with the O2 sensors cleaned I will try again. At least it’s running better with the new gas and not misfiring. I had no misfire codes in the system which is a good sign.

 

[marshallma0504]

As far as the readings go I can’t access the upstream sensors sadly on this scanner. I bought it because it was what I could afford and I don’t have a windows computer to use forscan at home. I know forscan lite is a thing but how good can an app on iPhone really be for diagnostics is my question?

 

[kryptto]

As far as the readings go I can’t access the upstream sensors sadly on this scanner. I bought it because it was what I could afford and I don’t have a windows computer to use forscan at home. I know forscan lite is a thing but how good can an app on iPhone really be for diagnostics is my question?

the android version is pretty comprehensive, though on the website it had all the tests and the non dangerous service options......

 

[marshallma0504]

Sadly I don’t have android so I gotta work with the autel scanner I got. Thanks for the input and I’m hoping to have it running efficiently soon. There has been less condensation from the tailpipes today then there was before as well idk if that’s related to temperature and humidity or directly related to how the car is running. Exhaust also smells normal not sweet or burnt smelling.

 

[Texas Marauder]

There is a version for iOS.

 

[marshallma0504]

I also need to check my knock sensor wiring again because it’s having a consistent knocking sound at 2000 rpm only? More audible when engine is cold and it idles smooth as butter after adding the 93 fuel. Also doesn’t knock on decel or under any kind of load. Just 2000rpm at idle. Very strange. Maybe I left a heat shield loose that’s rattling at that rpm but I did record it from putting my phone behind the engine in the firewall and it seems to be coming from there. I will take an oil sample to check for the worst, but I’m not convinced I messed up the timing job to cause engine failure if it can run flawlessly with no codes other than cat converters.