I have a 98 Civic EX. I've been having rough acceleration between 2 and 3K RPMs. I spoke with the dealership about this issue, but they can't detect any problems. They told me to run some injector cleaner through it to see if that helps. I added a dose of Sea Foam (I've heard good things) to the gas tank, and noticed an immediate increase in performance, but I suspect there's an additional additive in the product that causes this increase.

They also recommended that I put 89 octane fuel instead of 87, saying that I'd get better mpg, as well as increase the performance and engine life.

In the past I've heard that you can go up in octane, but if you go back down you can run into engine problems such as pinging, etc.

What do you guys think about moving to a higher octane, and do you feel these people are right?

 

Im assuming its a stock EX. Its not going to make a difference if you run 87 or 91 or whatever... the motor is made to run off of 87 octane. Like you posted above, it sounds like you need some fuel injector cleaner (additives)

 

yeah, the higher octane fuel really won't make much difference.

 

run the 91 every few months or right before a smog check, and get the Shell or Chevron 91, it has better additives than most places. but for normal daily driving, use the 87. try Marvel Mystery Oil or a fuel system cleaner by Berrymans. those are the only additives i ever use. the MMO is great, i also use it in the engine oil.

 

Thanks for the info. I'll continue to use 87.

I put the cleaner in the gas. I know you it can be put in a lot of places, like the brake vacuum line, etc. Is the gas the best place to put it?

 

whoa, i dont know about others. just the MMO is to be used in the oil and fuel. i dont suggest putting anything anywhere else.

 

what's wrong with using 91?

 

Burns too hot. If you drive it hard/long enough with 91, it'll warp **** (ask sacicons... he's been there...) I personally run 89 all the time, but mostly for the sake of fuel efficiency.

 

I have a 99 ex, and i had the same problem...kinda puttered a little at real low rpms when shifting and accelerating. I changed my fuel filter and PROBLEM GONE. This is a $10 fix and takes about 20 minutes or so, maybe less.

 

no, its not that it burns too hot. i had the problem because of those stupid Bosch platinum +4 plugs (actually, i was using 87 at the time.). the only problem with 91 is that its a waste of money unless you need it. actually, it burns less easily than lower octane gas. thats how it reduces detonation. and it can hurt power on an otherwise stock car, due to the resistence to ignition.