1986 CHEVY CK20 FAILED EMISSION TEST HIGH HYDROCARBONS
mccartlidge. are you serious?? high HC is the result of a headgasket problem??? do everyone a favor and dont give advice when you clearly dont know a damned thing about emissions. as far as solutions to your high HC output, someone else mentioned the possibility of a worn out cat along with carb problems and or a simple air fuel adjustment. this car if i remember correctly has a feedback carb which means it has an oxygen sensor and a mixture control solenoid on the car to fine tune the air fuel mixture. it is not uncommon to have a oxygen sensor not functioning at all or out of normal calibrated range. easy test for oxygen sensor(single wire oxygen sensor ) is to hook up a voltmeter at 0 to 1 volt range(positive lead to oxygen sensor wire, negative lead to any good ground source) and watch the voltage. a perfectly working system the signal should look like a wave constantly rising and falling from .9v-.1v. test at 2500 rpm as well as at idle on a hot engine.if the oxygen sensor doesnt rise and fall, add fuel(spray small amount of carb spray) into carb while at idle or high rpm and the oxyen sensor should go full rich(approx .8-1v) that is point 8(.8v) not eight volts. you will usually see a reading of .9v . if the oxygen sensor doesnt put out a rich reading than its no good. on the other end you can remove a vacuum line(brake booster hose, half way removed as to not stall the engine) the oxygen sensor should go lean which means around .1 volts. if the oxygen sensor does not respond correctly replace it. beyond that, the engine first and foremost has to run on all cylinders to run clean and efficient. if it has a missfire or dead hole that will cause high HC along with high CO as unburnt fuel is going out the tail pipe. i could go on and on about possibilities but figured i would give you a couple basics to go on. Good luck.
Aug 12, 2012 |
Chevrolet Chevy Cars & Trucks