LSWhat

How bad is it to run 87 instead of 92? I accidentally did that while I was in Oregon and drove it home one 87. Could that be why my cars missing? Or do I just need to do a tune up? I also have no CEL. It's a 92 LS400

RA40

iTrader: (6)

No worries, just fill it up with 92 and it will be happy again. Usually it won't miss but you'll lose a bit of performance and MPG from the lower octane gas. If it is missing, there may be other potential problems. Tank it up and see how it runs.

LSWhat

I've been running premium for a while now, since about monday. Haven't given it a full tank yet because I have no money till tomorrow. I'm hoping thats the cause of the miss because the first time it started missing was on sunday after I had been running 87, and the miss was pretty bad, but now it's kind of fading away, I dont know, it's hard to tell!

j three

Get some gas treatment and fill it up with premium. I recommend lucas for this as I have been happy with it, but at least get some kind to help clean your engine out some to see if it helps some.

williamb82

ive always used seafoam in the gas tank. usually jump on the interstate right after and can feel it when it starts working. though when i used it on my 85 supra i had over 180k on it. lol

LSWhat

Yeah the misfire seems to fade more and more each day. Like the other day it was stumbling over itself at 40, now there is no miss and 40, and the rpm's drop maybe once or twice at a stoplight or something. Whereas before, it would sit there and chunk itself, and if I let it idle away it would stumble the car too, now it doesn't do any of that! I don't get it!

Thermactor

iTrader: (1)

I've put 87 in my car before with no adverse impact. Sure, it had a bit more pep on Premium but it didn't make it misfire or knock.
Of course, I can't do that now, because the motor would die immediately and horribly if I did so, but still...

LSWhat

Well whatever was causing my misfire is obviously fixing itself. When I posted my rough idle thread I was freaking out because I know nothing about 1UZ's and I had a pretty bad miss. But now the miss is just about gone, I since then put in new plugs which helped. It doesn't miss near as bad as it did at stop lights and it doesn't chunk the car forward when I'm idling.

whiteivory

iTrader: (4)

I wouldn't put regular gas in there.
The octane level is resistance to detonation, so if you put lower octane than prescribed, chances your detonation is occuring before the piston had the chance to lift up to its optimal position, thus creating counter-productive energy.

That's my 2 cents, but why risk it when premium is a few bucks more?
I'm using 91 octane and now even thinking of switching to 94.

LSWhat

Running 87 was an accident. In Oregon you cannot pump your own gas, so dude filled it up with regular.

whiteivory

iTrader: (4)

Oh my apologies.
Didn't read it properly.

Short term will have very little adverse effect, other than loss of power and probably a bit of misfire/pinging.

LSWhat

Yeah it's not nearly missing as bad today as it was like sunday. Sunday I'd let it idle in drive and it would lurch the car forward. Now it's just smooth, misses only at idle but even then not bad at all. I still believe I need a tune up since the new plugs did help a little. Tune ups on these things are nightmares compared to what I'm used to. No need to apologize brother, I never stated it wasn't my fault anyway haha.

denverdog

1. there are lengthy threads on using lower octane gas. they give you a lot of information.

2. the lower octane doesn't cause a "miss" in the usual sense. that is usually an electrical problem leading to no spark.

3. it can cause early detonation, as that is why there are higher octane gasolines. yopu hear this as what is usually described as a "knock". it is didfferent than a "miss."

4. unless you drive your car very hard, or very heavily loaded, or up mountains, or tow substantial weights, the computer corrects for the lower octane and you probably cannot even tell the difference. the lower octane gas is not less powerful. its the exact same chemicals, just arranged in shorter chain molecules. there is a good "modern marvels" show just on gasoline.

3UZFTE

They are actually pretty easy to do. 8 plugs, 8 wires, 2 caps, and 2 rotors.

SRV1

iTrader: (2)

Just because you cannot hear the engine detonate does not mean it is not happening. We have compression ratios of 10:1 and that is why we need to run high octane fuel.

James