[SOLVED] Extremely High STFT LTFT and P0171 code

[arpypat]

Got the car back and it's running great!

Can't believe I shelled out $2k for 1 spark plug and injectors, but they did end up doing a lot of diagnostics:

• PCM replaced and programmed
• No vacuum leaks found
• No exhaust leaks found
• EVAP system OK
• Compression test OK
• Head gasket OK

Drove around for a bit and LTFT was between +0 to +2. STFT fluctuated only around +/- 5. It feels great even on the stock tune, but I want to make sure the optimized tune for my mods is loaded back on. And I'll put 4 fresh plugs in.

Appreciate everyone's help and @gtman - I'll update the Tuned Reliability thread with this failure. We see alot of P0172 codes from leaking injectors, but I don't know if we see many P0171 from clogged injectors.

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[gtman]

I know you spent a lot but honestly, I'm a bit surprised they warrantied the PCM with your extensive mod list so there's that.

 

[Zedaine]

Got the car back and it's running great!

Glad you are back up and running! And fairly quickly too. At least you put the dealership to work for the 2 grand and got a new PCM out of it.

Hopefully you wont have to do this again in another 60k miles

 

[arpypat]

I know you spent a lot but honestly, I'm a bit surprised they warrantied the PCM with your extensive mod list so there's that.

That's true! Though I'm not so sure the PCM was faulty in the first place lol

Glad you are back up and running! And fairly quickly too. At least you put the dealership to work for the 2 grand and got a new PCM out of it.

Hopefully you wont have to do this again in another 60k miles

Oh ya, I wasn't going to let them get away with just 1 spark plug for $150

I hope I can get more than 5 years out of these new injectors. I'll look into running injector cleaner periodically.

 

[gtman]

I've run Gumout Regane once a year. And knock on wood ...

 

[arpypat]

I've run Gumout Regane once a year. And knock on wood ...

Is there a particular product I should go for? https://gumout.com/our-products/#fuel-additives

 

[gtman]

Here's what I use.

I drive til the the low fuel light comes on. Put this in at the gas station and then fill up.

https://www.amazon.com/Gumout-510014-Regane-Complete-Cleaner/dp/B07R6B75N7/

 

[cryptolime]

i doubt the PCM was even bad. probably just injectors/plug.

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