i put new plugs in the car at 55,000 miles (93 GT) it now has 74000 on it. pulled the plugs out to put new ones in and noticed the plugs were white meaning the car must be running lean. is it possible for my fenderwell cold air intake to cause my car to run lean? should i get new 02 sensors? what else?
pulled the plugs, they were white
- Thread starter FiveO
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What octane fuel are you running? Is the engine pinging? My plugs are white and its running great. Close to 20 mpg in the city with no pinging on 93 octane. I drive easy most all the time. Run it at WOT and mash the clutch or just shut it off if its an auto. Then pull over and read them. Dont get caught by the police.
Michael Yount
Mustang Master
If your car is running ok and fuel mileage hasn't changed, there's nothing wrong. Mine is running perfectly also - drivability, mileage, performance - and I'd have to describe my plugs as "white" also. If you're truly concerned about there being a problem - pull your diagnostic codes first and see if there are any error codes, then follow that guidance. If there are no codes and you still want to know about mixture, instead of throwing money into new O2 sensors that $80-100 will buy you 3 pulls on a chassis dyno with a wide-band O2 sensor in the tail pipe. That'll tell you exactly what the a/f ratio is. My guess is that yours is running just fine. Have a Twinkie and watch Oprah.
I think your running ok, this time when I pulled my plugs the ceramic was white, but the ground electrode was the nice lightly tan/brown color. Check your ground electrodes on the combustion chamber sides to be sure. I think the ceramic self cleans when your running stoich most of the time, but the ground electrodes tell the real story.
Good Luck, Don
Good Luck, Don
sixty9boss302
Founding Member
i was just wondering but what do you mean by running "stoich" or refering to stoichiometry. I looked it up and it said some crap bout "the quantitive relationship between reactants and products in a chemical reaction..... blah blah blah" Basically is it a fancy word for your Air/Fuel ratio being properly balanced? haha sounds stupid but thanx
Michael Yount
Mustang Master
Stoichiometric means running at an air/fuel ratio where the amount of oxygen and fuel present are the perfect amount for complete combustion -- for our engines it's right around 14.7:1 air/fuel ratio. Theoretically that would combust all the fuel, and leave no excess oxygen or unburned hydrocarbons. However, it changes slightly due to the fact that we're not running pure oxygen (air is only about 22% oxygen), the fuel has many combustible compounds in it, not just octane (C3H8), etc. The most power is made right around 13-13.5:1 air/fuel. Overall emissions are minimized in the same range or just a tad richer (a bit less than stoich). In general, power will decrease as you get leaner or richer compared to the number above. And overall emissions will increase as you get leaner or richer -- however, each component - HC, CO and NOx does different things as you move in different directions from stoich. That's part of the challenge of meeting of emissions -- you go in one direction with mixture to solve say an unburned HC issue, and your NOx increases. Go the other way to solve the NOx, and your HC gets worse. Kind of a catch 22 that requires the engine to operate in a very narrow band of mixture - which is why fuel injection and feedback (O2 sensors) were developed. Probably TMI - too much information.
sixty9boss302
Founding Member
Excellent explaination and very well written you definately know your $hit. I understood it all and thats some good stuff to know. thanks for the info...later
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