Yes i do have several ideas on what happened, but i'd appreciate it if you can give me your 2 cents worth.
77K Miles, Yes, 77K miles only for an 18 year old car :)
Here are the issues i know
1. My filter is dirty, but c'mon, $10 - 25 miles?
2. My cylinder 2 Sparkplug o ring is leaking, the other 3 are ok, discovered this when i changed oil yesterday, spark plug was fouled...is that enough to make my car drink gas like a V8?
3. When i drive, sometimes after filling up i can see the fuel gauge drop significantly then go up again but it doesnt go up and down eratically, i just notice it every now and then.
HouseCallAuto 5/13/2011Here's my two cents worth Spoon, maybe even three cents. There is a very good chance that you have:
a) a bad thermostat that is stuck open causing a rich running condition at all times because as you know the link between pulse width of the fuel injectors and the output signal from the ECT sensor. This engine should be running at about 200 F and if it is running at say 160 to 175 you could expect a loss of about 30% of your gas mileage so check the running temperature after 10 minutes run time minimum. Your fouled spark plug might not be fouled at all. When the o-ring for the spark plug tube seal leaks into the spark plug tube, the oil remains there and does not touch the electrode at all. That only happens when you then remove the plug and as you do the oil that collected around the hex of the plug makes contact with the electrode as you unthread it. The misfire can come from the deterioration of the spark plug boot being in contact with the motor oil which tends to break down the boot material and then causes the misfire. But, if the spark plug were indeed fouled, then that would mean you would lose 25% of the engine power which would further decrease gas mileage. Lastly, check the ignition timing with a timing light and set it at spec or say 2 degrees more advanced at most. If the ignition timing is off the gas will disappear quickly as well. So, to recap........yes, you could get 10 mpg on that motor with certain conditions present. And one more thing, this is not OBDII. The fuel injection and computer programming is not sensitive at all and having no check engine light on is not really saying anything significant and lastly, have you jumped out the service check connector to see if any DTC's are present right now? No check engine light on does not always mean no codes.
Bill 5/13/2011Here is my 2 cents worth. $10.00 = about 2.5 gallons. Correct me if wrong here. This means if you know upon a shadow of a doubt without filling and refilling to get an accurate gallon input you are getting roughly 10 MPG. Ok, now comes the hard part. Put a new air filter in. Put new OEM type spark plugs gapped properly in. Short distances driven are harder on a vehicle because engine doesn't get to operating temp for long enough. Also this means a lot of carbon bild up in combustion chambers and all oxygen sensors and catalytic are probably carbon coated. I would get injectors cleaned and use a superior lubricating oil, then take for a freeway trip to burn out the cobwebs. Just a suggestion.
Spoon Sports 5/13/2011Thank you so much for the input bill, my friends is also suggesting cleaning them. Also, i only use the car once or twice a week so its average travel is 120-150 miles a month.
My friends didnt tell me about the carbon coating on the engine but you did and i agree with you on that.
Thanks again chief :)
jeep 8/7/2011It could mean you have a hole in your gas tank. Rusted through.
jeep 8/7/2011car is drinking gas faster than a v8. Check for hole or small hole where gas can evaporate.