i recently bought a 94 gsr (118k) and without thinking, i have been fueling my vehicle with a cheap gas. octane 87 to be exact. about three weeks in, i realized my mistake, filled the rest of my tank with high test (93) bought some octane boost.. that's where i am right now. since i am new to the vtec world, i have some worries. i pushed my car tonight and when pulling into the driveway, i noticed a strange sort of rattling when accelerating. sounded like loose change. the noise i think started around 3 grand when i was idling, give or take. i'm freaking out. are my worries correct? am i undergoing detonation? what's the noise? please, help a new kid out. thanks.

 

rattling? like loose exhaust bolts? exacly where do you hear the noise from, have you located where its coming from? i dont think changin your fuel octane will make a rattle noise? locate this noise, and let us know about where you are hearing it. and as far as performance, how does the car drive? smooth? rough?
-Jason

 

i dunno if im just being paranoid since i started reading about detonation a few days ago. it sounds as if loose change is being rattled inside my actual engine, car runs smooth, i don't feel any differences.

 

did you listen closely to your engine? does the noise come from the upper portion(head) or the lower portion(block)... rattling isnt always bad, but it helps to know where exactly the rattling is coming from. do you live local to anyone that can listen to it for you?

 

my dad has worked on fords for some 20 odd years, but he i'm not at his house. the noise i think sounds as if it is closer to where the manifold is located, and to be honest, i couldn't tell you if it was located in the head or not. the sound is not present when car is idle, only when accelerated. sorry if i'm not being to helpful with this.

 

no, its ok... just tryin to help you locate your problem...

 

I doubt it is detonation, most likely it is pinging(Pre-Igntion) due to a lack of correct ignition timing.
Finish filling out your profile so we know where you live and can help you further.

-Joe

 

so you can only hear it when you are accelerating? so then when you have the hood popped and you rev it up you dont hear it at all? it may not be inside your engine... if its only when its accelerating then there are many factors that can cause rattling... does the sound change when you shift gears at all? how about when you speed up or slow down? -Jason

 

no, i said that wrong. i had a friend jump in and rev it up for me as i hovered over the engine listening. i didn't notice any performance changes, i just had him in the car when i pushed the teg alittle down the road, pulled into the driveway, popped the hood and when i was reving, i was hearing some weird change sounding noises coming from my engine. i drove my car about an hour later (10 minutes ago) and i can still hear the sound when i rev and pop the hood, but i really don't feel anything when i drive the car

 

Sounds like Pre-Ig to me... bout you?