Sluggish and horrible gas mileage

[Soundwave.]

So ive noticed that for the last 4 tanks of gas, my car has been feeling slugging under acceleration and also been getting horrible gas mileage. I would say im getting 50-60 less miles per tank as well. I recently changed my sparkplugs about 2 months ago and i constantly keep my tires full of air and ready to roll. I also just changed my oil about 200 miles ago and ive checked my intake tube to make sure there were no cracks. I have noticed that there is no problem at all with idle, and there is also no smoke. Everyonce in a while, the car will act fine and accelerate like a dream but the rest of the time it is slow. Anyone have any ideas on what it could be?

 

[hornsfan10609]

The coilpacks and wires fail over time, autozone or rockauto is the cheapest place to find new ones. My old P5 used to run great after I reset the ECU. You may have an EGR sticking or a clogged fuel pump sock although that is not very common on these cars unless you have a lot of miles.

 

[Soundwave.]

The coilpacks and wires fail over time, autozone or rockauto is the cheapest place to find new ones. My old P5 used to run great after I reset the ECU. You may have an EGR sticking or a clogged fuel pump sock although that is not very common on these cars unless you have a lot of miles.

120k miles...

 

[915_P5]

Ive also noticed mine sluggish, changed the sri to stock intake with k&n helped out alot. But was thinking of doing the timming belt. My car only has about 132k so i think its about time to do the belt

 

[Soundwave.]

timing belt along with head gasket was changed at 80k

 

[hornsfan10609]

It is likely a worn ignition system, unless the injectors are clogging which is not very common.

 

[Soundwave.]

so...time for new wires and coil packs then? Judging by how they look, i can only assume that they are OE

 

[hornsfan10609]

I can't say for sure without the car in front of me but that is a necessary maintenance item for these cars. I don't really have much info to go on.

 

[Soundwave.]

I can't say for sure without the car in front of me but that is a necessary maintenance item for these cars. I don't really have much info to go on.

Yeah i understand i very much so appreciate what info you have given me. When i last pulled my plugs, they were burned clean so I know that the car is not running lean or rich. Im going to start with wires and packs and go from there. The car does seem to hesitate a little bit when i am going from a dead stop in first to second.

 

[Luken10]

Ive also noticed mine sluggish, changed the sri to stock intake with k&n helped out alot. But was thinking of doing the timming belt. My car only has about 132k so i think its about time to do the belt

Is there any truth to this? I moved my aftermarket intake from inside the engine bay to inside the front left fender and it seems like I am getting worse gas mileage. I used to get about 2-3 mpg better on canyon runs than I do now. I can't tell if it just because I am driving the car faster, or because of the air intake change.

 

[Soundwave.]

Is there any truth to this? I moved my aftermarket intake from inside the engine bay to inside the front left fender and it seems like I am getting worse gas mileage. I used to get about 2-3 mpg better on canyon runs than I do now. I can't tell if it just because I am driving the car faster, or because of the air intake change.

Yes there is. Some cars stock intake systems are already fully optimized to get maximum hp and air to the car already. Changing to a sri is actually worse on these cars if I remember correctly

 

[Soundwave.]

Also I should note that I am not throwing any codes

 

[pcb]

I remember installshield talking about how an aftermarket intake manufacturer was working with Mazda to design a better intake. They couldn't get it any better and the project was dropped.

 

[pcb]

I did this to my intake,... it's supposed to give a ram air effect.

It's free and easy and can't hurt (unless rain gets forced into the intake but that hasn't happened,.. there's drain holes in the intake system)


Here's a link about it...

http://www.clubprotege.com/forum/showthread.php?1977-Modifying-the-Stock-Air-Intake-System

 

[hornsfan10609]

I cut my grille like that too when I had my P5, never noticed any difference in MPG, power, etc.

 

[pcb]

I can't say I noticed anything either,... I just figure if it makes any difference, it's for the better. (shrug)

 

[Fresco]

The last time I had really bad gas mileage was in fact the gas (bp) itself, ever since I started using a different gas provider (sunoco) if have not had the problem again, I'm not saying its the gas company maybe something to do with the station owner but since going to a different station the problem has literally gone away, and my mpgs have increased

 

[pcb]

I had my mileage drop from 38 to 31 (Canadian MPG). Turned out to be the air filter. (which didn't look dirty). My mileage went right back to normal after replacing it.

 

[pcb]

The coilpacks and wires fail over time, autozone or rockauto is the cheapest place to find new ones. My old P5 used to run great after I reset the ECU. You may have an EGR sticking or a clogged fuel pump sock although that is not very common on these cars unless you have a lot of miles.

^ What he said.

If anyone reading this hasn't replaced their coil packs or they look original, just replace them. Think of it like an oil change and not a waste of money if it doesn't fix your cars problem. Bad coils cause engine misfire which can wreck your pre-cat in a matter of minutes. They can also give strange and intermittent symptoms which can be hard to diagnose. Even brand new coils have been known to be bad, right out of the box.

Engine misfire (P0300- P0304) is the only CEL code that flashes the CEL on our car, so you don't need a code reader to know what's wrong if your light is flashing. If that ever happens, pull over, shut off your car and replace your coils as the first step towards repair.

Don't forget about your fuel filter (fuel sender unit/fuel pump housing/high pressure fuel filter). Our cars DO have a fuel filter,... it's built into the fuel pump housing. After more than ten years now, I think everyone with a P5 should replace it. It's a $30 part from RockAuto but can be a PITA to replace. This is the only car I've dealt with where replacing the fuel filter isn't listed as regular maintenance.

http://www.mazdas247.com/forum/show...How-To-Change-Your-Fuel-Filter-(lots-of-pics)

 

[Soundwave.]

Cool. Ive always noticed that my car tends to run better with shell gas but this time I decided to use BP premium. Air filter was just replaced 3 months ago. Im gonna start with coil packs and go from there. I just hope its not a fuel filter problem. Luckily the previous owner kept reciepts for everything so ill just look there.