How do you know when a coil fails? Will one cylinder completely stop firing?

 

I had a set of the extremes early last year and had one fail...the car was missing and i swapped them one for one until i found a culprit....GMS accepted them back and sent my money back as i was not willing to deal with sporadic failures happening...they did provide a smoother cold idle and the car felt peppier with them in...never did a before and after dyno.

 

I have read and read and read about these COPs. While they may or may not provide a moderate increase in performance, idle quality, and gas mileage, the reason I will not invest in them is all the sporadic failures. In most cases aftermarket high performance is supposed to be better than stock. It dosn't really matter if there better if they fail. Even if the provider replaces under warranty, I do not want to be out on the road a couple hundred miles from home and have one go out.

I had the same issues on Accel coils some years back. (one Coil System) Accel replaced the ones that failed with even their higher quality ones and they eventually failed. I am talking about failure anywhere from 6 months to 2 years.

Don't understand why the aftermarket cannot provide the reliability of OEM. Unless it's a choice.

 

It's simple: The aftermarket doesn't have a FRACTION of the resources for design or test that the OEM does. Ford will use more COPS in a single day than Granatelli will in the life of the product. Because of that, Ford MUST make sure they have a very highly reliable product. Could you imagine what the headlines would read if Ford's stock COPs had the failure rate of the aftermarket COPs???

 

i concur