Will using low octane fuel cause lean condition?
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Instructor
Joined: Apr 2003
Posts: 211
Likes: 3
From: Sarasota FL
Will using low octane fuel cause lean condition?
Getting codes:
P0171H - lean fuel mixture bank 1 and
P0174H - lean fuel mixture bank 2
after "you know who" filled up with cheap 87 octane gas.
Check engine light is on and car is running a tad rough. No other PCM codes. Will a fill up with top quality premuim solve this problem? Should I add octane booster?
Thanks.
Andy.
P0171H - lean fuel mixture bank 1 and
P0174H - lean fuel mixture bank 2
after "you know who" filled up with cheap 87 octane gas.
Check engine light is on and car is running a tad rough. No other PCM codes. Will a fill up with top quality premuim solve this problem? Should I add octane booster?
Thanks.
Andy.
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Joined: Apr 2002
Posts: 726
Likes: 2
From: Denver CO
As far as a lean condition, don't know. The PCM will pull timing as far as it can, which may still be too advanced for 87 (OMG!!) octane, which could result in a lean condition. The PCM couldn't possibly be programmed for an octane that low, so I'm sure the computer is confused. The detonation in the engine's got to be horrendous. 87?!?!?! I wouldn't put that in my pickup truck.....the valves would rattle continuously.
For engine protection......I know it's a hassle, but if you could drain the tank it would be your best bet. Octane boosters are marginal. If you can't drain all, drain 5 or 6 gallons (put in your "other's" car) and, if you can find it, put 5-6 gallons of race fuel in there. That should boost you up to 92 or 93 octane. Geez, half a tank of 93 would still only get you to 90 octane. Not worth the chance of damage or lack of power when you need it
For engine protection......I know it's a hassle, but if you could drain the tank it would be your best bet. Octane boosters are marginal. If you can't drain all, drain 5 or 6 gallons (put in your "other's" car) and, if you can find it, put 5-6 gallons of race fuel in there. That should boost you up to 92 or 93 octane. Geez, half a tank of 93 would still only get you to 90 octane. Not worth the chance of damage or lack of power when you need it
Last edited by TopCat; Apr 21, 2005 at 03:28 PM.
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Joined: Apr 2004
Posts: 82
Likes: 0
From: Savannah GA
On my '99 Coupe, I get no PCM codes if I fill up with 87. That alone should not cause the problem. In fact, the user's manual says you can use lower octane fuels, but with a disclaimer that states you won't get the same performance results that you would with a Premium fill.
