atldave

I found a gas station that has no ethanol gas and decided to try it. The mechanic there told me that I should get more hp from the gas and that my 92 tune should be ok. I filled up and started, expecting the limp home light to come on. It didn't. I drove it pretty carefully for the next half hour with no problems. Since then I've been driving in my typical "spirited" style in town and up to about 80 mph on the highway. I'm not having any issues. Do you think I can rely on the idiot light, or is there a chance that I'm running lean and don't know it?

Also, the car seemed a little slower at first than it does with 92 gas with ethanol. However, as time has gone on, the acceleration seems to have picked up and now seems about comparable to the 92. Is this just my imagination, or is it possible that the no ethanol gas has "cleaned up" my ignition? Just wondering.

Nuke

Running lean isn't the concern. Detonation (knock) is. Lower octane fuel than your tune calls for can cause knock which can eventually damage the engine after prolonged use. The PCM can adjust by pulling some timing but only by so much. You can't always hear detonation (but usually you can). I'd load an 89 tune just to be safe.

tbar

All I know is tuners tell you not to run a lower octane then your tuned for, I believe it can cause detonation.

JIM5.0

The best thing to do is to use your ears. When you are driving, listen for knock. You can't miss it.

The idiot light does not light up in many engine knock situations. The only time the MIL comes on is if there is a malfunction that persists. For example, a misfire or O2 sensor failure etc. Of course the MIL would come on if persistent knocking causes damage to the engine.

atldave

Ok, thanks for the good feedback. I think I'll load in the 89 tune just to be safe.

aerbourne

youre a brave soul. id be way too scared to try that. I have nightmares about people filling my car up with 87 when im running a 91 tune lol

atldave

Aerbourne, I let it idle a few minutes after the first start and then drove VERY gently for a few blocks to check it out first. I never heard any pings or felt any hesitation. I switched to the 89 tune yesterday just to be safe. Funny thing is that there is almost no drop off from the 92. Usually I feel a big difference between those two tunes. The non-ethanol gas runs much better with the 89 tune than the typical gas I normally use.

Nuke

Your PCM was likely pulling timing with the 90 octane fuel so the switch to your 89 tune wasn't all that much, IMO. Also, unless you were getting on it on both tunes, it's difficult to compare.

Alec

Been there, done that. It's NOT fun. I know people say you'll be fine if you limp it home (which I did) but it's still nerve racking