In the last week my car is progressively getting worse. I have an appointment next week but I am driving 100 miles a day, now I am down to 21mpg from 29, idle is rougher than bass on full blast, and my rpms climb so slowly its more efficient to shift.. ANY IDEAS?

 

any check engine light?

 

yeah, if your tc is running that poorly, i would expect the CEL to come on.

i'm assuming this is a manual. what is your mileage, what mods have you done as far as intake and exhaust header if any. are you running the a/c, been keeping up on your oil changes and air filter cleaning?

 

I was thinking maybe injector issues, but wanted to see if he had a CEL first

 

this might not help but have you tried cleaning the maf sensor?
check the tire pressure?i guess those will mainly help with the mpg thing..but not sure about the others

 

Could also be cheep gas, faulty fuel filter or poss fuel pump.

 

No check engine lights, fresh oil change <1k miles, no mods; no intake or anything, tire pressure o.k.
Manual - I was averaging 28-32 progressively been dropping, it is now averaging 20. No climate change really, just some rain but no excessive a/c. I am going to check the air filter, I am at 25k miles and have not changed it. Also a friend suggested a fuel filter, possible, I don't know you tell me? I am using a different gas station now, always used the same one before and but the new one is still cheveron and my mileage is progressively getting worse not a symptom of bad gas.

 

It sounds like if it has gotten progressively worse then it may have to do with something in your ignition system deteriorating, maybe a bad/dead plug(s). I had a similar issue in a '00 Altima and found that when I pulled the boot to get to the plug, the contact in the bottom of the boot stayed attached to the plug while the rest of the boot came out. This led to the power not being transmitted to the plug properly, if at all, and left one cylinder dead.

Like Drax already asked, have you changed oil on time, with the proper amount? I come from the MKIII Supra world where rod knocks are a daily occurance; the way we used to check is to rev and hold (in neutral) at around 1500 then move to 2000 for a few seconds to listen for a clunking noise. Is there anything like that going on or just really shakey?

At around 100 miles a day it doesn't seem like bad gas would still be in the system after a week, unless you always go to the same station that is.


In a nutshell, check the basic ____ first. Make sure you have fuel and fire to each cylinder.

First, check for fire. Start the car and pull the plug wires one at a time; if the idle changes then that particular plug is working. If the sound does not change, then that plug is dead and should be pulled to be checked ofr fouling/broken electrode etc...

Not sure if our injectors can be check with the screwdriver technique or not, but if so then try that.


If everything seems to be ok you could always try unhooking the battery to reset the ECU and see if that helps. I had my MAF sensor unhooked when I restarted my car once and it ran like crap even after hooking it back up until I reset the computer.

Hope at least some of that helps... I will be watching for progres.

 

Thanks for the tips, I am reluctant to try the spark plug trick, I shocked myself pretty good last time.. I can rev it out to 6500 but its almost powerless relative to before.

 

I'm not very familiar with the ignition system on our cars but as long as the electrical connection stays (pretty) close to the vavle cover then you never become the ground.

Is there any black smoke at idle or while revving? Maybe loading up on fuel for some reason?

 

I skimmed through the posts, but I am wondering when was the last time you cleaned the injectors? what brand gas do you use?

just as an fyi, for cleaning injectors its best to clean them every time you get an oil change, despite the gas you are using.

Also are there any power mods? (didnt see any in your profile so figured I would ask)

 

I want to say yes to black smoke. There is a lot of suit? on the rear bumper. I have not cleaned the injectors yet, but I do not want to start throwing money at the problem before its properly diagnosed.

 

black smoke = rich. This may be due to an intake leak after the MAF sensor, check the seal around the throttle body?

If the MAF sensor were unhooked you would definitely have a CEL. In my past experience when a MAF sensor is unhooked the ECU will load up on fuel big time just to protect the engine from running lean. Maybe the MAF sensor is dead?

Does anyone know how to check the health of the sensor?

I would still try to check the plugs. Use a pair of insulated pliers to hold the connector if you are worried about getting shocked. If you find that one plug being unhooked doesnt change the idle then proceed to pull and check that plug physically for fouling or breaking.

 

Could I take this in to the dealer for drivability without the check engine light? I am hesitant to open the hood on this car, I make monthly payments to toyota so I don't have to. I've got a chevelle that desires to be worked on..

 

I believe if the MAF was out of range (dead) it would throw a CEL...

 

After thinking about this for a bit I think it very likely may be a clogged air filter... not sure though.

Also, if you find that the air filter is fine, you could still check the plugs with NO risk of getting shocked...

Disconnect the plug wire, THEN start it to see if it runs any different, if so, turn it off, reconnect, and try the next. Though, it may not run on only 2 cylinders if one plug is already out, never tried.

 

well if its been slowly getting worse, fuel injector cleaner is an easy and not too expensive way to check. Typically costs about $5-$7

 

Oh good idea on the spark plugs!! I am going to investigate the service interval for the air cleaner, it is probably a 15-25k mile thing. I am starting to feel that it is the air cleaner (at least hoping)..

 

You could always just remove the filter altogether to see how it runs without it. Though, you should NEVER drive it this way, it just may show you what is wrong

I would check all the easy stuff before dropping it off with a dealership. Worst case, warranty will be your best friend if it becomes a difficult problem to troubleshoot.

 

Any progress today? I am anxious to see what the problem is...