355 Knock Sensor Question

You better get a new diagnostician. Knock sensor error does not indicate a bad knock sensor. The knock sensor is an external part and cannot be harmed by fuel or additives. Knock sensor cannot cause a miss but can react to one.

You really need to find someone who knows how that car works before you replace a bunch of parts that are not broken but are just trying to tell a story and no one is listening.

 

A bad knock sensor will allow/cause knocking/preignition. Because it will not send the signal to the ECU to adjust/retard timming when needed.

Fuel additives will not cause a knock sensor to fail.

 

One error but at *least* two problems. Obviously a problem with the knock sensor, but keep in mind that you wouldn't even need a knock sensor if you had good fuel running in a 355 that is running 100% fine with good timing (valves and ignition) and good fuel/air mixture (and obviously no exhaust leaks or other major malfunctions).

I don't know about your 5.2, but Motronic 2.7 adjusts the ignition timing based on coolant temperature (richer when cold) and adjusts the fuel/air mixture for different things such as A/C being on, coolant temp, air temp, etc.

Since you are in an area remote from Ferrari professionals, you are going to want to help isolate your problem. For instance, do you get your miss/knock with your A/C on as well as with it off? How about when the engine/coolant is cold versus when it is hot?

Do you get it after you've added an octane booster to your fuel?

Are your spark plugs the correct heat range? Can you post a picture of the last set of spark plugs pulled from your car?

Click on my link below to learn a bit about reading spark plugs.

Also, some Motronic systems have the ability to be set for "low octane fuel conditions." I don't know if your 5.2 can be set that way, but that might be something to ask someone more knowledgable on this subject than me.

 

I know a very good mechanic in PR. Send me a private message, and I will give you his name. Unfortunately he is all the way on the other side of the island, and very busy, but he is an expert on Motronic systems.

Jay

 

Take Jay up on the offer.

The other advice being given is wrong.

You need a guy there who is a good motronics guy.