are we sopposed 2 run regular or plus or premium in these cars? i cant find a definite answer and i dont have an owners manual. my 85 tpi is usually ok....but it does sometimes have a rough idle...and it sometimes "pings" when im at idle. thats the only time. wierd thing is, i can hear it in the car, not under the hood. perhaps its because i have no insolation on the hood???

 

Well I mainly run 93 octane on my 89 305tpi. how many miles are on your 85? I just ran some lucas fuel cleaner through my s10 and it seems to run alot better. Try and run that through your 3rd gen. I picked up a bottle at mejer for 5$ and then run premium, thats what I prefer.

 

the car only has 74k on it. everything seems to run fine. it doesnt ping...u know like it does on acceleration. mainly i think maybe im just hearing the engine through the car because ive got no insolation on the hood (aftermarket iroc hood) who knows.....are they sopposed 2 run 89 or 93? from the factory?

 

I have been runnin 93 for 11 years now in my bird. Of course now I have the timming up around 12-15 deg. initial.

 

IIRC, 91 octane minimum was specified for TPIs. Your modifications and adjustments can change that requirement, however.

 

crap, so i shouldnt be running 87 (regular) in mine then huh. i have been with no problems. no pinging (i dont think).

 

 

so 91 then?

 

There are no absolutes. Carefully read the label on the pump from which you receive your fuel. The label will typically read "Minimum Octane, R + M / 2" which means the octane of that fuel may not be lower than what is displayed, but could be higher. "Regular" where I go is 89.

Your base timing may not be quite as advanced as on other TPI engines. Variations in production, slippage of the balancer outer ring, more or less sensitive detonation sensors, variations in programming, operating temperatures, combustion chamber condition and tempoerature, spark plug heat range, and other variables can result in different octane requirements. For a street driven vehicle, use the lowest octane fuel that provides good performance and no audible detonation. Lower octane will generally result in better fuel mileage.

 

ok cool...see i could find no definite answers on it. but that all makes sense.....the car runs fine on regular. i just didnt wanna keep using gas that i shouldnt be, u know? the car has a ratio of 9.5:1. i thought that sounded premium gas worthy....im still going 2 try different levels and see what kind the car runs the best at. mainly its an idle test for me. sometimes it idles rough with regular but with the plus so far its been idling alot smoother. it could just be me, u know? i had a problem with my car stalling in traffic because my idle just went too low to keep it running. thats seems like a massairflow thing to me though...i dunno...i havent figured that out...but either way, thanx for the help!