octane, timing, or the gingerbread man?

[Euphoric306]

ive noticed a little something, and was just curious as to the cause. i was going through a little financial rough spot (we all know how that can be) and was buying 87 octane cuz everything else was so damn expensive, so anyway, after i would take the car to WOT on the freeway or something, it would always make a small rattling sound when slowly accelerating (back to ~30 mph speeds) or going uphill, and i would have to push in the accel. or downshift manually to get the rpms up to stop the noise. the noise kind of reminded me of when you almost bog a manual transmission and it clanks kinda of, hard to explain

anyway, ive been putting 91 octane in lately and the noise has ceased to exist, as far as i have observed during the last few weeks. my point is, the same kind of noise was brought up in a recent post and the proposed cause was bad timing, and i was wondering if that could have to do with it as well, like if i reset my timing, would the noise go away with 87 octane as well? thanks guys, and as for the gingerbread man, he gives you bad indigestion (stay away).

 

[cjman15]

amen gingerbread man

 

[Sgt.5point0]

Hmm... I'm not the whiz in this are but I think you had detonation/pinging because of what your timing was set at using the lower octane fuel which is easier to detonate, the 91 octane resists detonation a lot better.

 

[HISSIN50]

others are right. i will say that i have never heard of anyone pinging upon deceleration (if i read your post right). new one on me. pinging occurs normally under load.

anyhow, it seems that you have deduced the problem. i would decide what you want to do with the octane and tune timing accordingly. rule of thumb is that you can run more timing with higher octane (as said, higher octane burns slower).

i normally run 87, so i set my timing accordingly. if you do the same, and then decide to run higher octane for a period of time, i would dial in more timing accordingly.

my misc ramblings. good luck.

 

[Euphoric306]

sorry post was a bit confusing, pinging (if thats what its called, ive heard this teerm before but never knew what it meant) would occur after decellerating back to town speeds and while accellerating slowly at about 1250-2000 rpm range. i guess the previous owner had the timing set to run with 91 octane, which wouldnt make sense because the car when i got it looked like it was the kind of car that ran cheaply and was only tended to when it was absolutely necessary (of course it has received much more tlc from its new owner -- me)