YACT: Can an anti-knock sensor get dirty/be cleaned?

[DurocShark]

Or should it just be replaced...

My volvo has always had a problem where it pings on accelleration. Only for the first like 1/8th second (one or 2 pings).

My local mechanic and I have determined the knock sensor is the last possible place, but expensive. He says it can't be cleaned/serviced. I'm willing to try, but I'd like to find out for sure before going through the hassle of pulling it out...

 

PLEASE




No it can't, have your mechanic remove the sensor, hook up a digital high impedance ohm meter to it, tap it with a wrench, you should see a voltage generated by it.

 

[Pepsi90919]

it sounds like it's working then? the knock sensor actually has to hear an audible knock and the computer has to have time to retard the timing, so one or 2 pings doesn't sound bad?

 

[DurocShark]

Originally posted by: Pepsi90919
it sounds like it's working then? the knock sensor actually has to hear an audible knock and the computer has to have time to retard the timing, so one or 2 pings doesn't sound bad?

There shouldn't be any at all...

And this happened with 2 different engines using the same sensors...

Roger: yeah, they put the voltmeter on the sensor with the engine running and it bounced around, but they didn't know voltages...

As for car specifics, didn't think it was necessary for this. 1984 Volvo 244GL 2.3l b230 (replaced a b23).

I guess I'll pop it out and replace and see if that helps. At the same time the cat is getting replaced (grrrr).

 

You must remove the sensor for testing, it is normal for a engine to knock once or twice before the ECM retards the ignition timing and richens up the fuel mixture, to be on the safe side, remove the sensor and test it according to my instructions.