Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB - Help! From check engine light to fouled plugs back to check engine + plugs refouling

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- - Help! From check engine light to fouled plugs back to check engine + plugs refouling (https://www.ft86club.com/forums/showthread.php?t=103070)

Quote:

Originally Posted by steve99 (Post 2608389)

get the dealer to log the long term fuel trims LTFT if they are over 10% or so then something is wrong with the fueling likely stuffed or dirty sensors ( 02 or maf) or injectors or intake exhaust leaks.

Quote:

Originally Posted by larchamb (Post 2607740)

check engine light back, and kick on deceleration at approx. 18 km/h
lol.....sigh

Quote:

Originally Posted by Spartarus (Post 2605628)

Read my previous post first....

NO NO NO NO NO NO NO NO NO. F*cking mechanics.

REPLACE THE COIL? Singular? There's 4 of them. 1 for each cylinder. Sounds like some missing information here. Also to answer your question YES. I would like to know which plugs are fouling. All of them or just 1? From your vague description, it's now hard to tell. And from reading my last post you should be able to tell the answer is important.

Replacing fouled plugs and coils and hoping the problem will go away is a bullshit band-aid fix that won't work for long, if it even works at all. That's just mechanics being lazy and not wanting to put in the work to diagnose the actual problem.

It's like putting a towel over a compound fracture and hoping it will go away if you don't look at it. The mechanics know that too, they're just being lazy... I know because I know many mechanics, and often have to beat them into getting off of their lazy asses and doing some real diagnosis.

If the coils were bad, the engine would throw a code to indicate the coils are bad.

The fact is, like many other people have already said, modern EFI engines DON'T FOUL PLUGS. If it's fouling plugs, there's a problem that needs to be fixed, not just replace the f*ckers and hope they don't foul again.

Has anyone thought of unusual valvetrain issues?

Quote:

Originally Posted by FRSBRZGT86FAN (Post 2608428)

Has anyone thought of unusual valvetrain issues?

The cam actuator operation/position is monitored pretty well you would expect codes related to cam actuators ect if that were the case.

Quote:

Originally Posted by steve99 (Post 2608482)

The cam actuator operation/position is monitored pretty well you would expect codes related to cam actuators ect if that were the case.

It's pretty mind boggling so many sensors and issues at least 4 or 5 off the top of my head could cause a "AFR imbalance", it's a pretty broad code, it makes sense the mechanics are having an issue with it then, or they are probably incompetent.

Quote:

Originally Posted by FRSBRZGT86FAN (Post 2608498)

Yeah maybe
but if its running pig rich you should smell it in exhaust fumes
then you need to find why its running rich. not just change the plugs.

although some people do weird stuff, guy over here decided he would run E85 on a stock petrol tune, cause he heard that you get more power ,then wonders why it running crap.

did not let on he put in E85 so your thinking wtf is wrong untill you smell the exhaust and it tweaks.

Quote:

Originally Posted by FRSBRZGT86FAN (Post 2608428)

Has anyone thought of unusual valvetrain issues?

Yes. But it it doesn't fit well for your problem...

We still don't have enough information.
@steve99 was correct in saying if there's a bad component in the valvetrain, you will likely have a related code...

If the variable cam actuators are anywhere in their mechanical range stuck or uncommon dedicated you shouldn't get serious afr imbalance sufficient to fold the plugs, it'll just run and idle like sh*t.

Little while ago a guy broke a valve spring. That won't throw a valve train related code, but you will have rough idling, afr issues, and random/multiple cylinder misfires.

Still want to know which plugs are fouling...

Theoretically, if you had a bad coil, the associated plug would foul, but the ECU on this car uses a crank speed variation algorithm to determine misfire, and you would have at least 1 misfire code.