Gas mileage getting worse yet

[s4983]

Okay, I wrote a while back about going from about 19 mpg to 14 within one week. Since then, it's gotten worse. This is not fun, especially with gas prices being as high as they are.

Last week, I purchased a fuel filter and my boyfriend installed it for me. The same day, he spent almost 2 hours changing out my spark plugs (which weren't in that bad of shape but we replaced them with new NGK's anyway). Since then, I feel a little difference, but not much.

I have no check engine light on, rpm's are fine, and the car 'sounds' normal...

A couple of strange symptoms:
- The night this all began, my car jerked everytime it would switch gears while I was driving home from work. I ended up shutting off the car and starting it again and it never happened again.
- When my boyfriend changed my fuel filter, about a cup of gas leaked out into the pan which is normal, but there were pea-sized bubbles of something floating in my fuel. water maybe? Is that even possible?


The only difference that I've noticed since I began losing the mpg is that it feels like it has lost some power. Going up hills is a b*tch... even after changing out the plugs, the car seems to baaarely make it up like Thomas the Tank Engine.

The only changes I've made to my car in the past 4 or 5 months are:
- magnaflow exhaust (5 months ago)
- K&n intake (4 months ago)
- Bf goodrich g-force sport tires (5 weeks ago when this started happening)
- Rims that are lighter than the stock ones i had (5 weeks ago)

I can't imagine any of those things making a difference in power OR mpg.

I've even dumped a bottle of fuel injector cleaner into my tank a couple weeks ago and no difference whatsoever.

Wednesday, I plan on taking it into a shop and having them test it with something that supposidly costs $50 but should hopefully tell me what the problem is. Not sure what this test is called but I've been told it's different than the one they do at Auto Zone for free.

I'd appreciate suggestions from you guys... You all know a lot more about this stuff than I do. I just want my car back to how it was :( :( :(

From reading these posts, my only idea is that one of my O2 sensors or my catalytic converter going bad. But is that possible with no check engine light coming on??

please help me. :cry:

[hockeyman]

Re: This is just lovely.

A clogged converter can definately slow your car, but I'm not totally sure that it will throw a code or not... If you find out later on that it's a bad converter, I'd strongly suggest going with a HIgh-Flow. You can buy them for about $65, and installation is about $80...unless your b/f can install it for you.

Other than that, you kind of covered-your-grounds by doing a tune up, fuel filter, etc. You didn't mention anything about spark plug wires though. You may want to have those checked if they weren't replaced. A small arc in the wire(s) can cause a world of heartache and money if it's overlooked:)

[s4983]

Re: This is just lovely.

Thank you for the reply Hockeyman!!

I failed to mention about the wires... I did actually have the wires replaced about a year ago.... Believe it or not, the shop I took it to back then "supposidly" did a full tune-up on my car, but when my boyfriend looked at the spark plugs they looked like they had a lot more miles on them than what I've put on in a year. He's convinced they never actually changed the plugs, but he said the wires looked like they were new.

Can't trust anyone these days.

[hockeyman]

Re: This is just lovely.

Then I'd focus on the converter. The next time your driving and it starts spuddering, hop out of the car and have a look at the converter it'self. If it's "cherry red" or "white (hot)" in color, it's in dire need of replacing.
As I said before, I'm not totally sure if a clogged converter would throw a code or not.

What kind of magnaflow exhaust did you install? Was it just the muffler or a full cat-back system?

Also, check your K&N Air Filter. Make sure it isn't dirty or clogged up.
I have one and I clean it once every 1,000 miles with soap/water, and I lightly spray WD-40 on it before re-installing.

[s4983]

Re: This is just lovely.

Awesome. I will definitely check the converter.

It is a cat-back exhaust.

Filter is clean.

Thank you so much for the suggestions. keep 'em coming! :banana:

[landj]

Re: This is just lovely.

Also, check your K&N Air Filter. *** I have one and I clean it once every 1,000 miles with soap/water, and I lightly spray WD-40 on it before re-installing.

WD-40 can be used instead of Charging Oil? I've been wondering what's in that stuff besides red food coloring!


Is the car downshifting when you are going up hills, or are the RPM's staying the same and the car boggs down?

[hockeyman]

Re: This is just lovely.

WD-40 can be used instead of Charging Oil? I've been wondering what's in that stuff besides red food coloring!

I've done some research when I bought the K&N filter, and found out that WD-40 does the same thing as the charging oil that's provided...easier to find in a store AND it's cheaper!

It's a win-win-win situation:banana:

[s4983]

Re: Gas mileage getting worse yet

landj, the car seems to be shifting normally when going uphill

[Camaro Dom]

Re: Gas mileage getting worse yet

little bubbles in the gas? that could lend to it maybe. make sure you're getting good gas and you dont let the car sit for a while w/o stabilizer. you can check the cat w/ a vacuum test. its easy as pie, you just hook the tester up to the brake booster line, start the car, and rev it to like 3000 and back down to idle. the vacuum should drop every time you give it gas, if it goes up, you've got an exhaust restriction (aka dead cat). and no, it does not neccessarily set off a code. i've gone thru two of them and havent gotten a code yet.

[s4983]

Re: Gas mileage getting worse yet

My car is fine.

It's gotta be the weight from the wider tires and bigger rims killing my mileage.

[Metallibird_Y87]

Re: Gas mileage getting worse yet

My car is fine.

It's gotta be the weight from the wider tires and bigger rims killing my mileage.

:twak:

[s4983]

Re: Gas mileage getting worse yet

THIS LAST TANK GOT ME 20 MPG!!!!!!!!!!!!

Fuel filter and new plugs. :banana: :banana: :banana:

[Jason3.4L]

Re: This is just lovely.

I've done some research when I bought the K&N filter, and found out that WD-40 does the same thing as the charging oil that's provided...easier to find in a store AND it's cheaper!

It's a win-win-win situation:banana:

Do you have a place that shows this? I am wondering because K&N Specifically says no lightweight oils (WD40, CRC, etc). I just would like a little proof it is time to recharge the filter in my truck and I am out of charging oil. Thanks!