1991 civic SI rough idle poor mileage

[Pistol1583]

I have a 91 honda civic SI 1.6 with about 90,000 on the motor. I have noticed a rough idle and poor gas mileage. I did a little tune up with new plugs, new plug wires, vacume lines, air filter, and injector cleaner. I have also noticed when i come to a stop and push the clutch in the cars rpms drop to about 200 and it almost stalls. I also did an O2 sensor about 1 1/2 years ago. I dont think its the gas because i use the same mobile station that i have gone to for years. any tips??

To remove this ad, register today for free or log in if already registered!

[04 Honda Civic]

I have the same problem Rough Idle try cleaning ur IAC. Didnt work for me but maybe it will for you.

[sp44]

I have the exact same problem on a 92 EX. Anybody find a fix?

[Silver06hemic]

Originally Posted by 04 Honda Civic

I have the same problem Rough Idle try cleaning ur IAC. Didnt work for me but maybe it will for you.

^^^^^
X2..... also give the TB a really good clean.... run the motor and spray it down whilst raising the revs to keep from stalling. The TB's on any car get gummed up over time... it doesn't take much cause a rough idle. The IAC will cause a constant 'searching' for revs (ie: a rev up and down up and down at an idle) and also in extreme conditions can cause stallouts. It's always good to give it a good spray down as well.

[Monotech]

Change your fuel filter,cap & rotor. To raise the idle, you have an idle adjustment screw on top of your TB. The wild idle will more likely be due to fast idle valve, just remove it and remove the 2 small phillip screws and remove the cover then tighten up the big plastic valve clockwise and whalah problem fixed.

[revr63ed7]

A d16a6 doesnt have a thermal fast idle valve to screw the plunger.

[sp44]

For me a new PCV valve fixed it!