Knock sensors test

[PynkEye]

Ok, i know on the old Supramania there was a thread on how to check your knocksensors, yet i didnt find it on this one. Was wondering if anyoen knew how to check them. Ive been getting code 52 for a long time, mega hesitation at beginning of boost, and underboost I just dont feel the max power (timing retarded).
Yes I have rewired my knocksensors, right after rewiring, for 2 weeks didnt get code, but still had hesitation, then all of a sudden the code came back strong..check engine comes on and off, but the hesitation is always there (dunno if thats normal), anyways, im guessing I got a back kncoksensors, But before buying one, id like to see if there is really one broken...or if I fucked upduring rewiring.

Thanks guys

 

[scottiedawg66]

check all your grounds for the shielded wire. IF those are off you will still get the code. I would go back and double check wiring, I have done 2 KS rewires, adn both of them I had to get a good ground before 52 would go away.

~scott

 

[PynkEye]

k, cool, ill check that this week end, hope its just that.

 

[shaeff]

check all your grounds for the shielded wire. IF those are off you will still get the code. I would go back and double check wiring, I have done 2 KS rewires, adn both of them I had to get a good ground before 52 would go away.

~scott

strange... after i did my rewire, i ran around for a week or so (had no time, i was working ridiculous hours) without the grounds connected, and never threw a code.

-shaeff

 

[devil358]

is this wiring issue a lot more common than actually having bad sensors? My supra is doing the same thing...but ironically, it's only when I'm cruising on the highway...I can push the engine hard on the backroads all day long, and nothing wrong at all....but if I get on the highway for about 20 minutes and drive at the same RPM/speed, the light always comes on...never fail...code 52...car drives like ass...when it hits boost...

more annoying over anything else....

 

[Supra Blues]

If you want to actually test the knock sensor itself, its pretty easy. The test is somewhat crude, but it should give you the results you are looking for.

1. Remove knock sensor from engine.

2. Hook up a volt meter to the knock sensor.

3. LIGHTLY tap on the sensor with a wrench or screwdriver.

If the volt meter spikes a little, then your knock sensor is working properly.

If it doesn't spike, check #2 above and repeat step 3. If you're sure it is hooked up correctly, and still no spike, then your sensor is bad.

Note: Knock sensors rarely go bad.

 

[PynkEye]

cool exactly what I wanted. I didnt do the grounds when rewiring, me and my father just didnt understand the point of having a ground to ground wire ....since there is accually nothing going threw a groudn witout having a positive...we didnt get it..anyways...we just didnt hook em up (kinda regret it now...if it accually does do something)
But most important ill check the knocks if they are good.
Oh and ive heard often the rewiring needed to be done, but also heard lots of ppl changing 1 of the 2 knocks sensors...probably 75-80% rewire...reste is bad sensor (for what ive seen since 1-2 years on this site.

Thanks again guys

 

[John Lunsford]

If you want to actually test the knock sensor itself, its pretty easy. The test is somewhat crude, but it should give you the results you are looking for.

1. Remove knock sensor from engine.

2. Hook up a volt meter to the knock sensor.

3. LIGHTLY tap on the sensor with a wrench or screwdriver.

If the volt meter spikes a little, then your knock sensor is working properly.

If it doesn't spike, check #2 above and repeat step 3. If you're sure it is hooked up correctly, and still no spike, then your sensor is bad.

Note: Knock sensors rarely go bad.

I similar but maybe easier way to do that is to lightly tap the block around the knock sensor and watch a timing light. When you tap it just right the timing will retard and you'll see it with the light.

 

[PynkEye]

ya good idea, but I have no timing light

 

[Dirgle]

The grounding is there to shield the KS wires from radio interference emitted by various electronic devices, primarily the sparkplug wires. This is done because the KS are extremely sensitive and can misinterpret electrical interference as a knock.

 

[PynkEye]

ya, but I didnt know that a ground to ground wire...that accually emits nothing...could shield radio interference. I did use r58 or whatever wire, with the wire around it, I thought it would be enough to just leave that there and it would protect the core...the wire plus the plastic thing around the core...

I just dont see what a ground to ground does...what goes threw it...anyways..dosnt matter...electronics aint my shit, im more mecaniques..i have to see da shit to understand it, and you cant see electiricty

Thanks

 

[Dirgle]

Na I hear ya man. :icon_wink As far as the ground goes the shielding basically picks up the electrical interference like an antenna before it gets to the KS wire. The electrical interference turns into energy and has to go somewhere, hence the ground. The reason it's grounds at both ends is because electricity follows the path of lest resistance. Having it grounded at both ends just disperses the energy quicker, resulting in a cleaner signal from the KS. That’s just the basic idea of how it works.

 

[PynkEye]

cool cool, sound a little clearer

Thanks

For that voltmeter test tho...I put the positive on the sensor (that goes in engine) and the negative of the voltmeter to what ??.the male connector ?