white residue on exhaust - throwing CEL error ?
 

About 1 week ago I put 116 octane gas in the car (mixed with some 93) to see what would happen I guess. Seemed a lot more responsive - but probably more psychological than anything.

I noticed my exhaust tips had a white coating on them (most I have seen seem to be somewhat black).

4 tank refills later and they are still white. But I was on a long drive from PA to boston the other day and all of a sudden by check engine light came on. Not flashing - just stayed on. 2 more tank refills later and it was still on. When I got back to PA I took it in to just check the code on this. It was throwing an error to do with running too rich ?. They stated its something to do with the cats and/or faulty sensor.

Do you think this is connected to my white exhaust residue and the 116 gas ?. Does running 116 gas void a warranty ?.

I did notice my tips were extremely hot after the 116 gas though.

Thanks for any input on this - may car is booked in next week for fixing and was wondering if they will give me warranty issues.

C16 is leaded race gas. It leaves the lovely white residue. C16 and cats is bad. So it is possible your O2 or Cat went caput. If a car is not tuned for C16, that can be bad. C16 burns much more slowly then standard 109 unleaded race gas. I guess what matters is what was the ratio you mixed with your pump gas?

Dan is right, time for a new exhaust at least!

Not sure what exhaust you have, but let me know if I can help. I would first get the CEL code read out.

Don't the pumps disclose lead content - the pumps at the station in the Denver area (Duggan) do - that's a pretty expensive mistake since lead will destroy the cats.

They dont sell C16 leaded race gas at a gas station to my knowledge. This is something you get from VP Fuels or at a race track... I would assume if you got it where you got it, then they would assume you know what you are doing. But hey, anything is possible!

I had a similar situation after hard run over the weekend at Watkins Glen. I noticed the exhaust tips (AWE system) were nice and clean, all the black residue burnt off with only a faint whitish residue barely noticable at the track. Two days later, while driving normally, CEL went on. Went to dealer for other issues and the light was off by then. Readout apparently had something to do with O2 sensor sniffing too much (?) fuel - maybe it was self reset to the leaner conditions of track use then noted change to rich ?? Anyway, was not a problem...but light came on again today!

Not going to worry, but will ask dealer (Main Line) to check it out again.

oh crap. yes 116 was obtained at a race track. Nope, didnt know what I was doing - my bad. You play you pay I guess.

so you think my cats are fried ? is it a matter of replacing just the cats or the whole damn exhaust ?. anyone know the approx price of this ?

stock exhaust.

My tips burn white after every trip to the track, stock and aftermarket.

how do you mean at least ? is there anything else that could go with what I did. I mixed about 2 116 to 1 part normal gas.

thanks for all your input here. so it looks like my best case is replacing the o2 (whatever that is) sensor or worst case replace the cats (assuming you can without a whole new exhaust).

it doesnt seem to have effected the performance of my car though - and there is nothing else wierd going on. what if I just left it ?. is that even worse ?

yes leaded race gas will kill your cats and you o2 sensors quick . and also fouls plugs up alot faster. get a catless exhuast and good tune with race gas file .

if you left it who knows, depends on what it actually is if its the cat then no .. go get the codes read out.

I would start with replacing the o2 sensors first, then if that fails exhaust upgrade time!
Just tell the dealer you were minding your own biz, just filling up at the gas station outta state...........

good idea. thanks for that. If my cat had actually failed - would the check engine light flash or just remain lit ?. in mine its just remaining lit - which according to the manual is lesser of a problem then it flashing.,

116 octane! holy smokes!

If the ECU is not timed for that you are wasting $'s.

I'll bet you will not try that again.

I hope it's just the O2 sensors slightly coated and reading erroneously. maybe once cleaned they will read correctly but it is possible you smoked the cats with the lead in that gas.

Keep us posted on that one.

BTW, we have 91 here in CA but sometimes the Union76 stations will have 92 which may actually be 93.

I bought a tank on the way to Concorso last year in Monterey, and I could feel a difference. But much more octane than that I doubt i would notice.