Is this bad?
#1
03-25-2009, 04:16 PM
Is this bad?
Yesterday I decided to use 93 unleaded instead of the 87. I had about 1/4 of 87 in the tank still. Well today after I used a little over a 1/4 tank it was a total dog. It was slow accelerating and down shifting all the time. It was just like someone flipped a switch, running good one minute and then not runnin good. So I stopped and filled the rear tank up with 87 but it still seems to be a dog. Is runnin 93 bad? I thought it'd be better for it that's why I put it in. Did I maybe screw something up?
It's a 96 351W.
It's a 96 351W.
#2
03-25-2009, 04:41 PM
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You should use what is recommended for your truck to get the most power and performance, 87.
You will get less power with the 93.
But it should not have hurt anything other than what is in your back pocket.
You might want to change the fuel filter now and see of that helps.
If not then see if you have any codes in CM.
You will get less power with the 93.
But it should not have hurt anything other than what is in your back pocket.
You might want to change the fuel filter now and see of that helps.
If not then see if you have any codes in CM.
Last edited by subford; 03-25-2009 at 10:46 PM.
#3
03-25-2009, 06:17 PM
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Higher octane fuel is harder to ignite and burns slower. The reason it is used in performance engines is that it has more detonation resistance and will withstand higher compression ratios without detonation. Because it burns slower, it is necessary to increase the initial timing advance to compensate. Since it resists spark knock better than low octane fuel so you can get away with the advanced timing.
If you simply put 93 in an engine designed for 87, you'll end up burning a substantial portion of your mixture in the exhaust system. One tankload won't hurt anything but if you do it all the time, you'll burn your exhaust valves and damage your catalytic converter. You'll also shorten the life of your exhaust system. If you bump the timing so that the combustion occurs where it is supposed to, you'll eliminate the potential for damage but you still won't be making any more power.
Always use the LOWEST octane fuel you can get by with without any trace of spark knock. On late model vehicles with knock sensors, this can be very difficult to detect so simply follow the minimum recommended octane rating of 87 (85 at higher altitude.)
If you simply put 93 in an engine designed for 87, you'll end up burning a substantial portion of your mixture in the exhaust system. One tankload won't hurt anything but if you do it all the time, you'll burn your exhaust valves and damage your catalytic converter. You'll also shorten the life of your exhaust system. If you bump the timing so that the combustion occurs where it is supposed to, you'll eliminate the potential for damage but you still won't be making any more power.
Always use the LOWEST octane fuel you can get by with without any trace of spark knock. On late model vehicles with knock sensors, this can be very difficult to detect so simply follow the minimum recommended octane rating of 87 (85 at higher altitude.)