P0172 code

[jokrz187]

I'm getting a bit frustrated with my car. I have had P0175 and P0172 come up over a few time individually. I just got the 172 and I'm at a end of possibilities before I go pay someone to do something I could have done.

Car specifics: Vararam Cai, moshimoto catch can, Dyno tuned, tsp headers, high flow cats, x pipe. 2015 as with 49,500 miles.

What I have checked and found:
On my catch can, the two hoses that connect up to the engine, have both been found popped off. I snapped them both back on. On the catch can it self, one fitting has been a quarter turn loose and retightin. Other than that I have found no hoses lose or anything. Can it be a fuel problem at this age of the car? She is not a DD anymore.

I am thinking of getting rid of catch can because it is a V8 and it really doesn't need it. Thoughts?

[FasNuf]

Do you have cats?
secondary O2 sensors?
How does your primary o2 oscilations look in the tune when in CL?
Check you MAF sensor
Bad leaking injector

[jokrz187]

Originally Posted by FasNuf

Do you have cats?
secondary O2 sensors?
How does your primary o2 oscilations look in the tune when in CL?
Check you MAF sensor
Bad leaking injector

I don't have cats, it's straight pipe back. And everything else you mentioned is above my knowledge. I check the MAF and nothing on it and wires are not broken in it.

[FasNuf]

Does your oil smell like gasoline? If it does, change your oil and see if the code clears. If it does but comes back after some time, it’s possible your injector is leaking fuel and getting in the oil.

['10CamaroDude]

There are no SECONDARY cat O2 sensors. The downstream sensors are after the
primary cat, before the secondary. The 2ndary cats are NOT MONITORED. You can
cut the 2ndary cats off, and have no issues what so ever. Also, the downstream O2
sensors ONLY monitor the primary cats. Those codes are upstream sensor related, which
are the ones BEFORE the primary cats. They're also called FRONT sensors. This has nothing
to do with the DOWNSTREAM sensors, at all.

It does mean the fuel concentration is too high:
Faulty Front Heated Oxygen Sensor
Faulty Spark Plugs
Faulty Mass Air Flow (MAF) sensor
Exhaust Gas Leaks
Ignition Misfiring
Incorrect Fuel Pressure
Faulty Fuel Injectors


More than likely, it's your tune, or tied to whatever else you've done.

You always go back to baseline to test, that means going back to stock.
If the codes stay away, then it's your mods and/or tune. We're all willing
to bet it was fine till your mods and tune was done.



V8 would need the catch can on the PCV side, not the clean side.

[FasNuf]

Sorry my bad English. I meant secondary sensor not secondary cat. Thanks Dude sounds like better advice than mine. Just throwing ideas to try

['10CamaroDude]

Downstream sensors have no effect on A:F ratios. All they're doing, is telling you
when the primary CATs go bad. So, you tune them out? That doesn't stop the
condition, it just turns off error reporting so the CEL does not light up. The condition
still exists, the error reporting is turned off. The O2 sensors will show up as
NOT AVAILABLE, -vs- NOT READY on an emissions machine.

The most common codes for the rear sensors are P0430 and P0420 when you open
up the exhaust in front of them. They still report to the ECU, even when the
CEL is set. Turning them off doesn't change it. You can remove them, and still
have no fuel:air problems. Downstream O2 sensor will not affect the open/closed loop
operation of the engine, only the upstream ones will. Open Loop due to a front
Sensor issue is bad for the cats... That is when the ECU alone is calculating
A:F ratios without the aid of the upstream sensor. The car will generally run
rich in open loop. Running lean would be bad for the motor, the cylinder temps
would go higher lean, so it's set to run rich in open loop so the motor doesn't
take damage. Burned out cats are cheaper to replace than the engine.

My rears have even set "no activity detected" codes, car didn't run any different.
In fact, it just happened this week. Dunno why, I get all kinds of random shit
with this car, with the rear sensors.

You only need to worry about the FRONT/UPSTREAM sensors for Air and Fuel.

[jokrz187]

Thank you, I have had the mods for two years almost three. Sounds like I'm going back to the tuner shop to have them look at it. I also changed the spark plugs before I went to the tuner. So when I got this code. One of the pcv tubes was lose on the catch can, could that have caused this.

Also, I would I smell my oil to see if it smells like gas? Can I pull the dip stick out and see?

['10CamaroDude]

The PCV could effect that if it were pulling in air where it was loose, but that would
generally cause lean, the unmetered air, thus not changing the fuel to compensate.

Yes, you can pull your dip out, or pull off the oil fill cap, and smell for too much fuel.
Though, if you have had the oil in there for 5000+ miles, it's hard to tell. If you
have been changing your own oil, you should know the difference in the odor if
there were too much fuel in it. That is usually due to leaking injectors, as fuel will
be leaking into the chamber(s) on every cycle, even the exhaust stroke, which is
raw fuel. Extra fuel sprayed in, only at that stage, is burned, and is not the same
RICH as leaking fuel. Same condition is set, but two different reasons.

If you gaped the plugs wrong, can cause this. So if it happened right after
installing spark plugs, sorry, you're gonna have to pull them and verify all the
gaps. Never assume the gap is pre-set. The box could fall, and smack one of the
ground electrodes off a hard surface, and push it closer to the center. Always
verify the gaps before installing.

[jokrz187]

Thanks for all the help, the plugs were put in at the time of the tune so they are about three years old. I pulled the dip stick and smell fuel, but not when I open the oil cap. It's been sitting for two days now. It's not a strong odor of fuel but you can smell it.

[jokrz187]

So I have a bad injector and today when I had her out. I definitely could here the misfire and I got a warning light for that. So question, since I am replacing the injectors, can I change them to something else or is there no reason. I need to read up on them but I am tuned with headers, straight pipe out the back.

[gtstorey]

I would replace with stock unless you plan on Supercharging or Turbo. If you go with anything different you will have to retune. I personally would likely replace just the one. If another fails fairly quickly I would replace the remainder.

[FasNuf]

Some injectors are packaged as a flow matched set so I would keep that in consideration.

[jokrz187]

Well I think I found one problem on way it ran the way it did. This was the spark plugs wire on passenger side first plug from the front of the engine. Then the third plug was not even attached to the plug. Things happen and I'm fixing it now and will report. Yes I have plug wire socks on my wires.