I accidentally put 89 octane gas instead of 91 octane in my 2000 si.
This was a fuel tank ago, but my car is still acting up.

at first, i couldnt go into vtec(past 5500rpms) at all..or at least it was hard to because it became sluggish near 5500. so i drove the car gently until the gas light came on and filled up with 91octane. I still have the vtec problem, but then it became worse..in first gear it would be sluggish until 3000 rpms and then it would kick in with power, but the vtec(around 5500) was still sluggish.

so i thought it was a spark plug problem so i got new ones and still the same problem. so i took those out and put in an extra set of civic ex spark plugs i had lying around in and now it runs good, but vtec is still sluggish, but not as sluggish.

but now, since im near the end of my second fuel tank..its letting me hit vtec again, but around 6500rpms or so it becomes sluggish.(im guessing because its not the proper spark plug). so today i put back in the si spark plugs, and it goes back to being sluggish in 1st gear and kicks in power at around 3000rpms. wtf???

i need feedback from those of you who have accidentally put 89 instead of 91 like i did! i need to know if ur cars performed the same way or not. How many tank fulls till it got back to normal etc etc. THANKS

im going to wait until the gas light comes on again and drive 30 miles(thats how much i usually can go after the light comes on) before i fill up again. hopefully it will be back to normal after this.

do u guys think i should put some fuel system cleaner in too?
any ADVISE is appreciated! THANKS AGAIN!!!

 

You can buy octane booster at your local autoshop.. that'll work.

 

How many miles on your SI? Maybe take a look at your fuel filter.. Also, is this the first time using 89 octane? mm... It shouldn't be that big a deal if you used 89 octane gas just once. I would think the ECU just retards the timing, etc, that's why your car is running sluggish.. Just keep using good premium fuel and maybe try some octane booster. I use Sunoco Ultra 94.. Good stuff..

 

I've put 89 octane in my b16, back when i had my crx. I never had a problem with vtec engaging.

Although my friend had a vtec problem a while back. I was a lil confused about it, but we realized he was actually low on oil. So check your oil, VTEC will go in and out if your oil is low or pressure is low.

 

Exactly my point.

You don't need to put high octane in a b16.
Honda recommends the 87 octane.

But GSR honda recommends the highest 93 octane.

 

I'd recomend doing a basic tune-up on the car...cap, rotor, plugs, wires and an oil change. Then add the octane boster and a full tank of 91+ octane. Hope that helps.

 

Honda recommends 91 for the B16A2, why would it say "Premium Unleaded Fuel Only" on the fuel door then? It even says in the manual use 91, anything less will result in lowered performance.

 

WREG93, you are 100% correct. On the fuel door of my SI it says premium fuel only. The b16 is a high compression engine, higher octane fuel is what's recommended.. Sucks that you guys only get 91 octane..
Definitely check your oil level also.. Good luck.

 

Ok you sir, need to stfu and stop giving out wrong info. 91 octane is recommended for b16's from Honda specifications.

 

holy ****....what about my b18b? do i need high octane gas too?

seriously....noob question of the day, someone PM on this

 

I always use 89 octane in my b16a sir2 and I've never had a problem with any of the **** you guys are talking about. Its probably because I've always run it on this, so I could see how switching it to a lesser grade might cause a problem, but I wouldnt think it would be to such an extreme.


[Modified by Nine, 4:36 PM 2/22/2003]

 

be that as it may....to get back to the original question....the octane of your gas should not cause any adverse effects on your motor. the higher octane rating is to control detonation, but it's not like you will instantly detonate if you have lower octane...you'd have to be doing repeated dyno pulls or something very stressful on the motor.

did you hear any metalic pinging? if you are having problems go to your local autoparts store, and buy some octane booster. if this does not fix your problem, you need to move on to some diagnostics.

 

its funny that you put lower octane gas in your si, because I did the same thing only worse. I put 87 octane, it was when I first got my car. I was so used to putting 87 in my jeep that I just did it with out even thinking. Anyway, before I finished pumping I realized my mistake but it was too late. So I stopped filling and paid for gas and bought a bottle of octane booster. I put the octane booster in before I even ran the car, and before I filled the tank it had about 1/4 tank of 91 already. So I only really put about 12-$15 of gas in the car. Anyway, I put the whole bottle of octane booster in the tank and started the car. I didn't really notice any mechanical problems just a little heistation when flooring it. But that was cleared up on the next fill with pure 91 octane.

 

if ur anywhere near 30 or 60 service times..things tend to be more sensitive to fuel and air eviormental changes..tune-up time

 

yea, i had half a tank already before i put the 89. I was on my way up to the bay area from the los angeles area and i just left with the gas i had because i know that gas prices are cheap off the 5FWY just about 50 miles along in my trip.


[Modified by VtecBio009, 11:21 AM 2/23/2003]

 

I'm sorry guys but I feel sorry for the people who live in California. You have 91 octane, and we here in Fl have 93. There is also a gas station just around the corner that sells 100 and 110 octane along with the other stuff (87, 89, 93).

 

I think if you don't use 91 Octane, your ECU automatically reconfigurates so you don't screw up the car. Try resetting the ECU with high octane