knock sensors and 100 octane fuel

[Dante]

I have a question , about a year ago i replaced a bad knock sensor and car ran fine with no codes. Recently i decided to fill up with 100 octane fuel to try out on a 4wd trip as soon as i was on the beach and giving the hilux a bit the codes came up for both knock sensors . After refueling on lower octane and ressetting ecu , codes still remained i then thought possibly faulty wiring surely both knocksensors couldnt go at once . So after stripping down motor and checking wiring and knock sensors i found that both knock sensors were faulty. After replacing both knock sensors every thing is fine and now i am too scared to use 100 octane fuel . Has anyone else had this experience or is it one of those unexplained weird coincidence things. Any feed back would be appreciated.

 

[George_R]

They might have been faulty long before you tried 100 octane, I'd honestly be more concerned of valves and stuff than sensors when trying high octane fuel

Toyota ECUs are known for very basic and primitive self-diagnostic features, compared to say ford, vw and some others.

 

[Dante]

Sorry if i am not understanding how can 2 knock sensors both be faulty when 1 is 1 year old and the other is 23 years old, what i understand how they work is that they send a self produced voltage to the ecu when they sense pinging noise. The computer will throw a code if it doesnt pick up a signal from the sensors. They both went from producing a signal to no signal ,100 octane is supposed to stop any pinging which makes sense why a code could be thrown but why would it stop them from sending a signal at lower octane or once pinging commenced again. I had them tested and they were both gone. Has anyone else used 100 octane and have or have not had these symptoms? Thanks

 

[George_R]

How did you test them?

 

[Dante]

I fitted them to my beachbuggy with the same motor and it showed the same code.

 

[George_R]

Does make sense, have you tried fitting them one at a time? It's VERY strange they both failed

Mate runs 1uz with twin turbo and LPG which can be regarded as high octaine in terms of knocking, and his knock sensors never failed

 

[Dante]

Tried fitting them one at a time yes and both had failed tried the new ones and no problem. Like i said its one of those strange things . Could it be possible that no pinging (no sensor activation) + heat from motor + bouncing around from 4wding ,cause the sensors to fail ? . Has anyone duplicated these conditions?.

 

[BlackUZZ31]

any corrosion on the terminals?

I'd suggest if you are going anywhere near salt water you check, clean and apply dielectric grease to all connectors!

 

[Dante]

Terminals fine.

 

[gloverman]

What did you torque them up to?

 

[Dante]

When i replaced one about a year ago I torqued it down to specs and didnt touch the other one that was probably there from when the engine was new. When i got to the beach and started to do some roosters the codes came up straight away, i wired up to the ecu the wires required to show codes and had them behind glove box on standby . As soon as the engine malfunction light came on I checked it and it showed both codes for both knock sensors. I failed to believe that both could go instantly and thought it must be wiring related but after various testing it was definetly the knock sensors got me buggered. When I say doing roosters I mean 2wd sitting on revs between 5000 and 6000 rpm. If you google "dantes ute" you will see some rooter action at lancelin in my ute listen for the supercharger.