Gas Mileage and power loss

[JCS]

'93 MX3, 1.6l, 5spd.
167k miles

Recently at highway speeds the rpm's would drop, then rpms would rise back to where they were and the car would obviously jerk. I cleaned out the tb, changed spark plugs/wires, dist. cap/rotor. Everything seems to run fine now, but I noticed that it seems to have lost a little bit of power and my gas mileage has also went down from 27/town - 32/highway to about 24/town - 27/highway. Anybody have any ideas what would have caused this? The only thing I could think of is the spark plugs were NGK brand with the fancy little platinum tips that you can't gap.

Only odd thing i've noticed otherwise is: When the car is started up and it's very cold outside, I can hear a whistling noise if I push on the gas a little. The noise increases with RPM's so maybe a vacuum leak is to blame. (NOTE:whistling noise goes away once the car is warmed up)

Any ideas are appreciated

[Daninski]

Funny as I was adjusting the Idle the more I screwed out the screw the more whistling sound I got from my CAI. Sounds like you could have a vac leak. You could also try putting the car in diag. mode and re adjusting your idle. Take the screw right out make sure it's clean screw it back in gently reseating it then screw it out to the original point start the engine and when warm adjust your idle.

[JCS]

What should the idle be set to?

[Ryan]

Dude, it says on the underside of your hood.

[JCS]

Well Ryan...thanks for the answer.

Guess any form of information is acceptable...

[fowljesse]

I don'r know about your particular area, but around here, they switch to Ethanol in the winter, and it SUCKS. Worse performance, and gas mileage.

[JCS]

I'm 2 hrs away visiting my g/f at college so I have no clue what they do in this town. I'll have to check it out at the pumps.

[fowljesse]

I'm not used to this. I've never lived where I couldn't find a non Ethenol station. I pay attention to evey fill up, and one day, outta nowhere, 26mpg, instead of 30. I thought something was wrong with my car, as I had also noticed it being slightly sluggish.. Then I saw the sing "Contains up to 10% Esthaintol"

[JCS]

Drove all over town and can't find anywhere that's not "enriched" with ethanol. I just went ahead and filled up with 89 instead of 87 since it's "supposed" to have less. Doubt it's worth the extra 10 cents per gallon but oh well.

As far as the idle speed, I can't find anything under the hood that has it. Sticker evidently fell off.

[SuperK]

There are only a few gas stations that are not mixed with ethanol now.
Most BP's in TN and AL are all 10% ethanol
Just about all gas stations in my county are 10% ethanol

The only place I can get 0% ethanol is a tiny little PURE station on the georgia border.


It sucks

[JCS]

Anymore ideas folks?

[shameem]

If you still have the original 16 year old O2 sensor - it might be time to change it....

[SuperK]

Also, you might want to adjust the ignition timing.

It's possible your injectors are gunked up... I would suggest running some cleaner, maybe seafoam or lucasoil...

But if there is a serious issue with the injectors, they'd have to be removed and professionally cleaned.

Double quadruple quintuple check your vacuum, pay attention to the accordian tube.

... and change your air filter if you haven't done that

I super suggest changing your O2 sensor as well.

[fowljesse]

D) All of the above.
A major tune-up would be good. Alot of injector cleaners are mostly Acetone. Try 2¾ oz. Acetone per tank (You can get it @ Home Depot, or any hardware store). It also relaxes the tension between gas molecules for better atomization. You'll get better gas mileage, anyway.

[JCS]

I've ran a couple bottles of injector cleaner through the car within the last few months, and i've also used Seafoam. I did a tune-up very recently, less than 3k miles ago. Air filter was changed around 10k miles ago. It snowed tonight and it's only supposed to be 3 degrees tomorrow but i'll change the o2 sensor when the weather clears up. I'll also check around for vacuum leaks.