Diagnosing P0172!
 

Hello everyone

I have been getting a CEL P0172 where the car starts but stalls every time to a point where the engine dies. So far I found out that the engine is
running rich. The only thing that I changed out was the stock pump with a deatschwerks 65c. Drove about 3months before this problem. I can datalog the scenario with my openflashtablet but I don’t know which parameters to record. Can anybody help me find the cause of this.

[UPDATE]

-I datalogged the scene for a clearer picture.

https://datazap.me/u/ishfaq-rubab/st...log=0&data=1-5

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Check your air filter, if it's VERY dirty, you'll run rich.

If you're still running rich after you have replaced or at least cleaned the air filter, then pull the mass air flow (MAF) sensor out and clean it with mass air flow sensor cleaner, let it dry completely before reinstalling it, then clear your ECU of any remaining codes.

Get back to us.

I cleaned the MAF sensor with the crc maf sensor cleaner. cleaned the airfilter, cleared out the codes but after starting the engine. the CEL lights up then it stalls till it dies. im sure its not the MAF or the airfilter.. one thing I noticed while I was datalogging the incident was that the O2S2 voltage was 0 the whole time. can it be the source of the problem?

Sent from my SM-G975U using Tapatalk

I tried going through the possible causes as mentioned

1.MAF cleaned and reseated.
2.the two vacuum lines were clamped.

But the only thing that I didn't get was the oil catch can overflowing. (mine does not have a catch can) I apologize for being a noob but can anybody help me understand the fix.no 3 or redirect me to a guide or something?

Try posting a data log, some knowledgeable folks here may be able to see a problem in there. It should naturally record all parameters.

I would check ALL lines for leaks or cracks just in case. How old is your vehicle? Any mods on it other than the fuel pump? Were you experiencing any other issues or odd things building up to this?
What made you replace the fuel pump? Maybe there are other issues related to the fuel system? - Fuel pressure regulator, restricted fuel lines, bad fuel injectors.

P0172 is a pretty general code and could be a number of things.
1. Bad or dirty MAF (seems like you've checked that already). Though it could potentially still be the cause if it is simply not working properly anymore.
2. Faulty O2 sensor (unlikely as your car should turn over I would think and be able to run, but possible).
3. Spark plugs (unlikely unless you have been experiencing a loss of power for some time now).
4. Injectors (rare to be the issue on this platform as far as I know, but possible).
5. Fuel pressure regulator.

EDIT: Out of everything mentioned, I think the most likely culprit is either an air leak somewhere in the hoses or something with the fuel system causing you not to get enough fuel to keep the car running. So I would do a solid check on all the hoses, especially at their bends and clamps. Then look into fuel system related items that I mentioned above.

Thanks i'll go through all of it again.
I datalogged the whole scenario, all fingers crossed!! thanks you all!

https://datazap.me/u/ishfaq-rubab/st...log=0&data=1-5

@Dzmitry

Vehicle Mods

- HKS v1 Supercharger
- HKS Superfire Racing Spark Plugs (installed it while dealing with this issue.)
- Deatschwerks 65c
- Grimspeed Airfilter


** Apart from the stalling, the rpm hesitates to go up upon wide open throttle. A sort of popping sound came from the engine bay when instant accelerating. I suspected it was the DI injector seal and got it changed but the problem remained like before. I also checked almost all the vacuum lines including the one under the manifold and found no potential leaks.

Thank you @Dzmitry and everyone for your precious time.

@steve99 @tomm.brz Any thoughts on the datalog?

I have little experience in reading these and understanding what's going on. As you stated before, O2 sensor 2 seems to remain at 0 volts the whole time, so maybe the issue?

how much bigger is that fuel pump? Too much pump can over run the fuel pressure regulator. This will definitely make it too rich.

Obviously this can be other things, but I'd look at that if you've done the other common stuff.

I've seen this before.

Also, if these cars have old fashioned fuel pressure regulators, and they fail, it usually fails rich like this

@JohnH Im afraid the pump that i'm currently using is specifically made for the 2013 86. I don't really think that might be the issue here.

-Pump Details
https://86speed.com/deatschwerks-fue...-dw65c-brz-frs

Yes @Dzmitry, I suspect the same. I recently purchased the part but haven't installed it yet.. can you tell if 02s2 (shown in the OFT) is the downstream or upstream?

Sensor 2 is downstream, after the cat.

Sensor 2 is usually not used in aftermarket tune since it is for cat efficiency(I believe).