[Zac]

I have seen this happen on newer non American cars. It seems certain stations have this problem happen while other stations do not. It is no certain brand so it must be the type of pump. Certain Shell stations here have this problem while others, I would imagine they are newer, do not.

87 octane should not hurt the car as the car's electronics should retard timing if it is needed.

 

[Zac]

always try to stay with what oem specs are and what they reccomend. the rating on fuels is nothing other than a ping rating. absolutely nothing will ever happen if you use 87 it may not burn as clean as 91 obviously. but as far as power gains lol please... thats like saying puting in 110 octane in a car with a compresson ratio of 9:1 is gonna make it faster LOL .


as far as your specific problem goes it could be many things and to many for me or anyone else on this forum to speculate on. it sucks any way u slice it especially for a new car.

gl


Irei

Is your argument saying that you will get the same power on 87 as 91 or that 91+ will make more power. A 350Z will NOT make the same power on 87 as it will on 91, the ECM will retard the timing.

 

[Zac]

yea, just cxause you lose power by going down on octane rating(because of retardation by the knock sensor) isnt the same as saying you will gain power by going up...

This is true...I guess I worded that awkwardly. The car will not be making its full potential because of the knock sensor (I assume the Z has one) will retard timing. Dyno graphs will show this on Spec Vs which use 87 while dynoing. Their graphs look somewhat like a richtor scale.

 

[Zac]

Blown head gaskets, too. Depends on the engine. Some engines, such as the 4G63, simply melt the pistons before the headgasket goes. I have personal experience with that.....

I've seen it!!! (crap, my buddy was pulling bad knock on his heavily modded 4G63 with 93 octane).

 

[Zac]

Might as well also add, when fuel is reformulated (oxygenated), I have always been told to consider bumping up octane as it can cause pinging or premature burn, especially vehicles with excess carbon build up. I know that MD is reforumlated in winter months, and PA is not. Premium is generally 93 here, and 94-98 is readily available. I would imagine Cali is oxygenated. The STi may simply not be able to take reformulated 91 octane without having a serious reduction in timing.