Stage 1v4, 87 octane code and rotten eggs

[PhatWeasel]

This is a comment/question for LAN, but I posted it in the public forum to see if anyone else out there has experienced this.

I am running ECUTune Stage 1v4 on a '95 L-AWD with 91 octane fuel. On a whim I switched the ECUTune code set over to the 87 octane position and drove the car to dinner to see if I could feel any performance difference. (Side note: Honestly I could not feel a difference, but the ambient temperature was down 20 deg. from earlier in the day.) After an awesome feast of sushi and Asahi beer (not driving now :)) I returned to the car to discover the most horrid of rotten egg smells had formed in/around my car! I immediately switched back to 91 octane code and the nastiness went away within a few miles of open window driving. I am assuming that the smell was my catalytic converters telling me they were not happy.

LAN, any ideas why this occured? Is this problem going to occur with 87 octane if I need to run it as well?

[SVXRide]

Are your 91 and 87 octane fuels blended the same? I wouldn't think anything that the 1v4 chip does would cause the egg smell, though I do agree it's your cats that are the cause of it....
-Bill

[PhatWeasel]

Are your 91 and 87 octane fuels blended the same? <snip>

I was running 91 octane the whole time.

In my understanding there should be little/no difference in performance and function when running 91 octane in an engine tuned for 87 octane. Of course all my personal research was done using old Ford and Toyota engines of ~8:1 compression ration where the phrase "Minimum Octane Rating" means just that. SVX engines are new territory for me, but I don't see why an engine tuned for 87 octane would have a problem with 91.

[ensteele]

So you had the 91 octane in the tank at the time, but switched it to the 87 setting? Why would you do that? I wouldn't think that would be good unless you put 87 fuel in the tank. :confused: :confused: :confused:

[PhatWeasel]

Like I said, the experiment was from the old school of thought. Back when there was a minimum octane rating and anything higher didn't really make a difference. If the machine was designed for 87 octane, you could run 89, 91 or higher and never know the difference, except in the wallet. Perhaps my experiment wasn't thought out all the way through seeing that the EG33 is a far cry from Ford's 400M V8.

[ensteele]

I see your thinking now. Good point. :) :)

[want-a-fast-svx]

pretty sure it shouldnt matter in any engine if you run higher than normal octane. All the octane rating is, the gas' ability to resist knock, *I believe, Im sure someone will chime in if im wrong* Therefore I dont see why it would of made a difference...However it did so something was going on...

[intelisevil]

Could some of the other members please 'flip the switch' and see if you get similar results?

Dan

PS: I own one but haven't installed it yet.

[dwd1985]

I remember reading the owners manual for my old work truck, which was a 2000 Ford F-250. It specifically said that the truck was designed to run on 85 (or 87? I cant remember) octane, and that using anything else was dangerous and would cause knock.

[SVXRide]

I was running 91 octane the whole time.

In my understanding there should be little/no difference in performance and function when running 91 octane in an engine tuned for 87 octane. Of course all my personal research was done using old Ford and Toyota engines of ~8:1 compression ration where the phrase "Minimum Octane Rating" means just that. SVX engines are new territory for me, but I don't see why an engine tuned for 87 octane would have a problem with 91.

Got it...I misread your original post....I think LAN is the only one who can authoritatively answer your question...my understanding is that the "87 switch" just changes the timing table so the engine won't knock when using 87 octane. The rotten egg smell could be the result of the cats not heating up as much due to a cooler exhaust temperature (?)

-Bill

[PhatWeasel]

...my understanding is that the "87 switch" just changes the timing table so the engine won't knock when using 87 octane.

That was my understanding as well.

The rotten egg smell could be the result of the cats not heating up as much due to a cooler exhaust temperature (?)

If the rotten egg smell was a result of cooler exhaust temps, wouldn't the car smell like rotten eggs for the first few minutes when you start it up? I am pretty sure the smell was caused by excessive exhaust temps. Then again I didn't bother to stick a hand underneath and see if it felt any warmer than usual.

[want-a-fast-svx]

I still dont understand why running it on the 87 code would cause this as octane is only the gas' ability to resist detonation or knock. Come on LAN where ya at ;) ???

[longassname]

I developed the 87 octane code back when my car had a cat and it never smelled like rotten eggs. I think you just ran over or parked over something. No one else has ever complained of my software making their car smell either.

[Earthworm]

Maybe he's just trying to say his car now "goes like stink" with the Stage I chip :D

[PhatWeasel]

I developed the 87 octane code back when my car had a cat and it never smelled like rotten eggs. I think you just ran over or parked over something. No one else has ever complained of my software making their car smell either.

Is there anything wrong with running the 87 octane code with 91 octane gas in the tank?

[oab_au]

Is there anything wrong with running the 87 octane code with 91 octane gas in the tank?

No it won't change, or hurt anything. The rotten egg smell is caused by the amount of sulphur in the fuel.

Harvey.;)