pollito14

While I'm uninstalling some electric horns that I installed before, I noticed that some cables rubbed up against the power steering pulley belt. I could see some of the cable broke and I don't know what they are from. I wonder if they could be the cause for my idle trouble. To better describe which cables they are... where I measure the oil on my 1.8 DOHC engine, there are some cables that come down from the intake manifold area. They run along the pass side of the valve cover and have a plug/connector that continues the cable down. They then disappear under the pass side of the engine. I can't see clearly where its connected. Anyone know what they're from?

kansei

sounds like its the wiring for the crank angle sensor .

pollito14

I think you're right. It goes to the pulley at the bottom that moves all the others. Do you know it's function?

kansei

Its main fuction is for misfire monitoring . Repair any damage and tape them up and tuck them back away from the pulleys and you should be ok.

pollito14

Yeah I plan to repair it, but I'm still not clear on the function. Sorry to keep buggin' but I'm just curious. How would it monitor misfire if it's connected to the crankshaft pulley?

kansei

Well it monitors crankshaft speed. The crankshaft will travel at an even predictable speed, in the event of a misfire the power stroke of a piston is lost and the sensor will pick up the slow down of the crank as the powerstroke is lost. It can tell which cylder misfired as the crank pulley has one different tooth that the sensor sees as #1 cyl and knows the relationship of the other cylinders from this. If the sensor reads two or more misfires it will set the light.and if it can't tell which cyl for some reason or more than one cylinder is at fault it will set a random misfire.
These codes are :
P0300 - random misfire
P0301 - Cyl #1 misfire
P0302 - Cyl #2 misfire
P0303 - Cyl #3 misfire
P0304 - Cyl #4 misfire
Hope this helps you understand.

pollito14

That is MUCH better. Now I understand perfectly. I had orinally understood that because of the sensor the engine could misfire but now I understand that it's a sensor that tells the OBDII if there is a misfire. Cool. Thanx a bunch