Changed to 91 Octane and car runs leaner

[yukon]

1993 240sxSwitched from 87 to 91 Octane and now my idle is much leaner. I used to be rich at idle but now I'm at the optimal mix during idle. My idle temp has gone from 183 to 185 F. My timing is still at 20. Is this logical? I have a smog test tomorrow.

[cotbu]

you don't fail emissions test for being stoichiometric....! You fail for not being!

[mr.booie]

you don't fail emissions test for being stoichiometric....! You fail for not being!

hardly anybody on this forum even knows what stoichiometric means... lol

just switch back to your normal gas if 91 is giving you problems. no brainer.

"if it aint broke, don't fix it"

[yukon]

you don't fail emissions test for being stoichiometric....! You fail for not being!


It scares me. When it is not stoichimetric it is running a lot leaner than it used to at idle. If I pass with flying colours Im going to punch someone in the face for not telling me about this.

[gijoe69]

Seafoam the car and change out the plugs

[StalinDrift123]

ive been running with 91 on a freaking sohc for a while now and passed the smog fine. i noticed my car idles smooth and stuff. im pretty sure its not good for the sohc but whatevers.....ill just get another engine.