Idle speed affecting mileage???
Thread Starter
Joined: Mar 2008
Posts: 63
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From: Orlando, FL, USA
Idle speed affecting mileage???
I have a 92 Accord EX, and lately it has been getting worse than normal mileage. When I first got the car roughly 6 months ago, I did all maintenence items. I did a full tune including wires, cap, rotor, fuel filter, valve adjust, pcv, etc. I used all Honda parts. I also changed the oil and seafoamed it (intake only) and ran some injector cleaner. Shortly thereafter I installed a AEM short ram air intake. I also cleaned the TB. The car has new tires on it, and I keep them aired up. I took a trip not long after all this work was done and I got 32-33 all hwy. Then to and from work (20mi one way, 15 of which is hwy) even with A/C on I was getting no worse than 28 in mixed everyday driving. So I was averaging about 30 mpg.
Well....my last couple tanks, I got around 23 mixed....same route and type of driving as before. This tank, although I haven't calculated it yet, seems to be going at the same pace. I don't drive aggressive, in the morning I keep the A/C off (with windows shut and fresh air vent blowing) and I am conscious in general of mileage. Well it's not helping.
The only thing that I have changed on the vehicle is idle speed using the adjustment screw on the TB. The reason I did this was with the A/C off, it idled smooth around 750-800 but with it on, the car idled down to the point where the car was vibrating very badly...and of course it bogs down a lot easier also with the 5spd. (Side note: I have cleaned the IACV and adjusted the FITV like discussed many times in this forum. I have also tried another IACV, same story.) So I adjusted the idle up to where it was a lot smoother with the A/C on. With A/C off, it idles at about 1000 RPM, and with it on...about 750-800. It's much better now regarding vibration and bogging. I know 1000rpm A/C off is higher than spec, but I don't know if that will affect gas mileage (remember, 75% of my commute is hwy)....or could there be something else going on?? Thanks for any help.
Well....my last couple tanks, I got around 23 mixed....same route and type of driving as before. This tank, although I haven't calculated it yet, seems to be going at the same pace. I don't drive aggressive, in the morning I keep the A/C off (with windows shut and fresh air vent blowing) and I am conscious in general of mileage. Well it's not helping.
The only thing that I have changed on the vehicle is idle speed using the adjustment screw on the TB. The reason I did this was with the A/C off, it idled smooth around 750-800 but with it on, the car idled down to the point where the car was vibrating very badly...and of course it bogs down a lot easier also with the 5spd. (Side note: I have cleaned the IACV and adjusted the FITV like discussed many times in this forum. I have also tried another IACV, same story.) So I adjusted the idle up to where it was a lot smoother with the A/C on. With A/C off, it idles at about 1000 RPM, and with it on...about 750-800. It's much better now regarding vibration and bogging. I know 1000rpm A/C off is higher than spec, but I don't know if that will affect gas mileage (remember, 75% of my commute is hwy)....or could there be something else going on?? Thanks for any help.
Thread Starter
Joined: Mar 2008
Posts: 63
Likes: 1
From: Orlando, FL, USA
Re: Idle speed affecting mileage??? (turbocivic1984)
I thought about that, but I don't have a C/E light on....and I would hate to shotgun that kind of money at the car without really knowing the problem. It would be an expensive guess...
How common is it for an o2 to go bad w/o throwing a light?
How common is it for an o2 to go bad w/o throwing a light?
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lax1089
Honda Accord (1990 - 2002)
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Apr 4, 2007 09:27 PM