i’m looking for the major causes…and some of the dumber less common ones. My neon is running lean…pulled the plugs today and they are a bit too white on the ends and my gas mileage SUCKS!
Maybe fuel pressure regulator or clogged fuel filter?
injectors
usually the your car gets better gas mileage when you go lean…
clogged injectors, vac leaks…
not in my case. my primary o2 sensor was bad and it was telling my car it was running lean. my car then overcompensated and started dumping fuel into the cylinders. my gas mileage went from about 28mpg to 21mpg. my car also ran like shit, rough idle, poor performance, etc…
possible causes for a car running lean…bad o2 sensor, fuel pressure regulator, clogged/dirty fuel filter, dirty injectors.
so your car was running rich not lean!
^ yea overcompensation would mean rich. But i pulled my plugs today to find oil in plug # 4…and the threads on the plug seem to be widen’d and almost stripped…get the head rethreaded or buy a complete top end?
The overall problems on my car are as follows(this may help u guys a lil more) EGR sys failure(2nd time the light came on for this) My injectors may be bad…seafoam cleaned them up for a while and mileage went back up but not for long, oil in plug #4, plugs were gaped at 040 when on neons they should be 035(corrected this problem), loose bolt near the cat which rattles from time to time
The lean issue might be the first O2 sensor (upstream of the cat) going bad. This is used by the PCM to calculate A/F ratio.
All your other problems, ???
EGR valves in general suck. You’d either need to pull it off and clean the passages, or replace it with a new one.
The oil on the plug could be the spark plug tube seal.
That loose bolt isin’t causing an exhaust leak?
^^ i’m pretty sure it is causing a leak…i know those cause mileage to drop but honestly i’m burning a full tank from ABOVE F to the needle below E in about 155 miles
Yeah, that’s 15mpg if you’re filling it with 10 gallons or so. I’d be surprised if you were running lean and getting 15mpg unless you had a hole in the gas tank or something.
are you sure it’s running lean? post a picture of the spark plug that you pulled. It has been in my experience that when an o2 sensor goes bad, it makes the car run rich, not lean. Usually when they go bad, the computer goes to running the car at open loop.
That exhaust leak will throw your o2 sensor off and will make your car run fairly rich. I would fix that before anything.
If it really is running lean, I would look into the fuel system, i.e. fuel pump, fuel injectors, fuel regulator, fuel filters, etc.
you can check to see your o2 sensor counts if your car is obd I fairly easily… just do a quick datalog.
It sounds like the exhaust leak might have fouled your o2 sensor and your car is now running at open loop.
no hole…hasn’t been any residue on the sidewalk since my tranny fluid leak which has since been fixed. but i will def start checking where you said and get you guys a pic as per danhr
Edit: oh i’ll pull one of the first 3…threads on #4 are starting to scare me a bit since the oil was found in the 4th plug…i don’t have a donar head for my car and don’t want to ruin the head and have to get it rethreaded
Oil on the threads isn’t really anything to be scared of. That is usually from a leaky valve cover gasket or a messy oil change. Unless the oil on the thread looked milky, then you are good. You probably should find out where the oil is coming from before it gets ugly.
don’t worry about your egr valve… your egr is only used for 5 minutes when you first start up your car… it isn’t going to kill your gas mileage by 50%
don’t worry about the threads… perma plug makes a spark plug thread repair kit for such things… no need for a new head for your car.
:rant:Quit being a drama queen:scared: . You are acting like your car is about to blow up when it just sounds like it needs a lil tlc .
^corrected…and i’m pretty sure it was about to blow up…pulled the dipstick same day…BONE DRY…i’m asking myself wtf…oil changed somewhere shy of 2000 miles ago and this car doesn’t burn oil(that i know of)…dropped a quart in and it registered on the stick…f’in neons
no u drive a neon, you’re a queen.:greddy:
so where are the pics damn it?!
and that disappearing oil trick is never good… start looking for leaks… check the valve cover and head gasket
:kekegay: