olszowa12

My car started to run a little rougher at idle than usual so I took it for a diagnosis and the STAR software found an error - the fuel ratio is too rich in the first two cylinders.

Could this be a side effect of removing my seconadary cats and replacing them with straigh pipes?

TIA.

Matt

Sincity

Wouldn't it be a sensor issue since the system adapts?

bhamg

Probably not. An O2 sensor has to pass a "readiness" test first. Once it passes the ECU adapts. In this case fuel trim cannot be adapted to be lean enough based on O2 sensor readings so the fault code is thrown. Still, it could be defective but I'd be inclined to look upstream first.

Mort

Don't think it is related to the removal of the secondary cats and funny it is just the first two cylinders. First two cylinders or both on one side? Maybe check for an intake blockage of some sort. Maybe injectors are sticking open?

olszowa12

I don't know which cylinders exactly. I wrote everything I know in the first post.
My car is getting Service B in two weeks so I'll get it done then.

I just wanted to know if any of you expierenced something like this before.

Thanks for all the input

bhamg

Based on what little is know this is a good bet. Normally I would suspect a MAFS issue but that possibility is virtually eliminated with the "two cylinders" thing.

Paculdo

to the OP.. have you resolved this issue/concern?

just recently, the car is having a rough idle/start - to the point that the car almost died.

the last time this happened, i parked the car and after 30 minutes came back and started the car. oil temp was at 190; coolant temp at 180; rpm was just slightly below the first bar (from zero); i just filled the car full (gas); outside temp is 60 degrees; A/C is OFF.

now i'm paranoid that the car might not start or die when my wife drives it.. she'll freak out and might attempt to restart (and restart) the car -- might cause (more) damage to the car?

thanks in advance

Paculdo

by the way, the car is stock

BerBer63

first 2 cylinders are passenger side

Paculdo

i guess i need to go to the dealership and have the car checked to see what's going on...

Merc63

Faulty injector, Faulty O2 or MAF.

Mort

Getting a check engine light? Could possibly be bad gas.

Paculdo

Shell premium gas (93).. i only put gas in 4 shell locations in my area since forever..
no check engine light.. i wish it would do CEL so when i go to the dealership they'd see it.. this morning, it started fine. i'll watch out/observe over the weekend.

anyone think the dealership would bother looking at the car (to check) without the CEL? and all based on my story? car is CPO.. the problem too is that my ever dependable SA is gone and i don't like the last SA that i've dealt with :-(

Paculdo

by the way, would a tune fix this issue? or is this something that technicians needs to check/change any hardware stuff to ensure all things are working on the car? thanks

mbguy949

spray the intake down heavily with brake clean or something similar to check for leaks, I have replaced a few c63 intake manifolds with small leaks giving similiar codes.

olszowa12

Either I got used to it or it's working smoother now.
I don't get the error when connected to STAR any more.

I was told that it was caused by bad fuel but who knows.

jvanbrecht

I got this a while back, but it was the entire left bank, not just 2 cylinders. It was the air intake gasket that needed to be replaced for me.

Paculdo

anybody have experience with a dealership that charges diagnostics fee up front?
i mean, they need to diagnose it right? otherwise, how could they know what is wrong (or not wrong) with the car?


*hopefully just a bad gas - as this is the only variable that have changed/happened in the last couple of days. full gas from that one shell location. if this is the case, then the dealership won't find anything then??? is it still worth having the car checked? or wait for a few more days to observe the car?

Paculdo

did you get a CEL?