RANDOM/MULTIPLE MISFIRE, KNOCK SENSOR #1+#2 ???

[andrewsl]

I have had two different mechanics tell me two different things on what is going on with my Q. First one said to change spark plugs again from Bosch to NGK before he would do anything. So I changed plugs and it did not make a difference. Then he tells me that he would recommend changing a coil pack that I just replaced days ago along with the plugs because it was not a brand name he recommended. I would not do that so I went to another mechanic. After some trouble shooting he said that everything points to the left bank knock sensor and that he would recommend changing both while he was at it. But when I picked up my car from him (keep in mind he done nothing to the car but hook it up to his machine) it ran just fine. So about 1-1 1/2 miles down the road it starts in, the missing, jumping then blinking service engine soon light for a moment then steady. This car does not have just a little miss it is very sick, no power, jerky and running very rich. Can the knock sensors be causing the random multiple misfire? Also can someone tell me how to check my coils with a voltmeter to see if they are bad or not?? Sorry for the ignorance, I am used to working on my '72 Nova. Thanks for any help that you can give.

[Q45tech]

Coil failures are common after warranty as are knock sensor replacements especially if engine ever allowed to overheat [even a minor one cracks housing on KS].

One reads FSM and follows the diagnostic proceedures line by line.Usual result is new oem coils, spark plugs, and KS.

Often a MARGINAL Coil will be damaged [failure accelerated] just by changing spark plugs, so we warn customers to just budget both every 100k, then no surprises.