Recurring P0354 P0352

[Mr.Scion]

Hi Everyone!

I’m having some issues and I am seeking some advice.

My car has been tuned by Delicious for full bolt on for 4K miles now, recently the car threw 2 codes. P0354 and P0352. I replaced both coil packs and the plugs were replaced about 5k miles ago. 2 days after I replaced the coils, the same codes popped up. Cleared them, popped up again. The codes only come on at idle in slow traffic, they do not come on while driving at highway speeds.

What could be causing the codes?

2014 FRS
40k miles
Full bolt on
Raceseng crank pulley
Skunk2 intake
Header back exhaust
Delicious tune

TIA

[Mr.Scion]

Bump

I am thinking it may be a bad engine harness or an ECU

[RZNT4R]

Originally Posted by Mr.Scion

Bump

I am thinking it may be a bad engine harness or an ECU

Rather than the code description, what you need to know are the detection criteria. Being on vacation I can't just login to our system to check, but what is recommend is spending a few bucks for a temp sub on TIS. It's like 15-20 $ and you'll have 3 days off the same diagnostic info the dealer has.

Throwing parts at a code on it's description alone isn't the way to do it. Subaru doesn't use an igf circuit like Toyota typically use, so ignition coil performance has to be modelled from other factors. The ecm may be monitoring the waveform on the trigger circuit, or it may be a completely indirect monitor based on other factors. Without knowing that, you effectively know nothing about the codes.

[MCTeeJ]

A data log with Ecutek would be helpful to your cause too, to see if cyl 2 and 4 are actually experiencing any misfire. Sad to say it does sound like a harness issue considering the codes come on when you're not really doing anything. Did you replace the coils with the updated version?

[guybo]

You would have saved a lot of money going to a shop to do the diagnosis, you could have fixed the issue yourself most likely.

Throwing parts at a problem and trying to read codes literally almost never fixes anything

[FRSBRZGT86FAN]

Originally Posted by RZNT4R

Rather than the code description, what you need to know are the detection criteria. Being on vacation I can't just login to our system to check, but what is recommend is spending a few bucks for a temp sub on TIS. It's like 15-20 $ and you'll have 3 days off the same diagnostic info the dealer has.

Throwing parts at a code on it's description alone isn't the way to do it. Subaru doesn't use an igf circuit like Toyota typically use, so ignition coil performance has to be modelled from other factors. The ecm may be monitoring the waveform on the trigger circuit, or it may be a completely indirect monitor based on other factors. Without knowing that, you effectively know nothing about the codes.

DO NOT waste money on a techstream subscription, there are full service manual dumps available on this forum. Techstream will only give you that same access

[Ultramaroon]

Or you could just click on the link in my sig.

[Mr.Scion]

Thanks for the help everyone. I did bring the car to the shop and they recommended a shotgun approach.
Replaced the engine harness with a new oem v1 harness.
Replaced ECU.
Replaced tune.

It wasnt the cheapest repair but the issue is gone.

[guybo]

Give it a couple days. IMHO that's the wrong way to diagnose that problem. A lot of shops employ parts puter-oners and can't do diagnosis. Did they test for vacuum leaks or do a compression test?