Help with Code 34 - Knock sensor!

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Ka24DET-S14
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Joined: Mon Oct 11, 2010 7:16 pm
Car: 1995 S14 Working on KA-T setup.

Help with Code 34 - Knock sensor!

Postby Ka24DET-S14 » Sun Jan 29, 2012 9:33 pm

I finally boosted my 95 KA-T and everything is good so far except I get code 34 on the ECU. I took out the sensor and bought a new one and replaced it. But still code 34! Here's what I have tested and done:

I get 4.88 volts to the clip that connects to the knock sensor with ignition on, with the sensor disconnected. Checks out fine (I'm supposed to get 5v).

I get 2.53 volts when I plug the clip into the sensor harness and again, it checks out fine for what I have read on other forums since the sensor adds resistance. (I'm supposed to get 2.5v)

However, I have noticed that once I turn the car on the voltage increases to 4.55 or so when the car reaches 180-195 degrees! I'm not driving the car I just let it idle to get to that temp range. Even if I turn off the car, then put it with key on ignition I still get the high 4.55 volts even though the car is not running.

Can anyone suggest anything? I bought a new sensor harness and I hope that does it. I even added grounds and no use. The sensor checked out at .566 ohms resistance so it's good.

Thanks guys!


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Razi
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Re: Help with Code 34 - Knock sensor!

Postby Razi » Sun Jan 29, 2012 9:52 pm

You probably have, but I'll ask anyways; have you reset the ECU after you change sensors?

Ka24DET-S14
Posts: 33
Joined: Mon Oct 11, 2010 7:16 pm
Car: 1995 S14 Working on KA-T setup.

Re: Help with Code 34 - Knock sensor!

Postby Ka24DET-S14 » Sun Jan 29, 2012 9:57 pm

Razi wrote:You probably have, but I'll ask anyways; have you reset the ECU after you change sensors?
Yes sir! Each and every time I test I clear the codes. I proceed once I get a code 55 for all clear.

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Razi
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Re: Help with Code 34 - Knock sensor!

Postby Razi » Sun Jan 29, 2012 11:37 pm

Strange.
My experience was a smooth one.

Have you tightened it to the specified torque? I'm not 100% sure but I think they need to be torqued to the factory spec to work correctly.

Ka24DET-S14
Posts: 33
Joined: Mon Oct 11, 2010 7:16 pm
Car: 1995 S14 Working on KA-T setup.

Re: Help with Code 34 - Knock sensor!

Postby Ka24DET-S14 » Mon Jan 30, 2012 8:20 am

I hand tightened it. Ill loosen it up a bit today and check with the voltmeter if it does anything! Thanks again!

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neverlift
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Re: Help with Code 34 - Knock sensor!

Postby neverlift » Wed Feb 01, 2012 6:24 am

wiring needs repair.

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lexcrob
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Re: Help with Code 34 - Knock sensor!

Postby lexcrob » Tue Feb 07, 2012 12:07 am

^ hack hack and run new wire*


repair.... waste of time for shur id imagine it would need to be shielded in some sort of way tho. That may even be some source of your problem! (the gray tape with the wires inside of it all over nissan harnesses looks like speaker wire with a wire in it.....) I HAVE NO IDEA HOW TO RECREAT SHIELDED WIRING

Ka24DET-S14
Posts: 33
Joined: Mon Oct 11, 2010 7:16 pm
Car: 1995 S14 Working on KA-T setup.

Re: Help with Code 34 - Knock sensor!

Postby Ka24DET-S14 » Tue Feb 07, 2012 12:00 pm

I got a new harness in but I have yet to install it. What I did to temporarily fix the problem is soldering a 1 mega-ohm resistor to the signal wire that goes to the ECU. Now all I get it code 55 and I have to say it was absolutely MURDERING my power and MPGs! The KA boosts like a rabbit dog at 10psi now and now I idle well and MPGs are better and response is way up! Ill get to fixing it sometime later, damn the knock sensor my newphews 1995 is also having the same issue with code 34...the resistor did the job for him too.

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lexcrob
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Re: Help with Code 34 - Knock sensor!

Postby lexcrob » Sun Feb 12, 2012 11:56 am

Im gonna have to say that is a bad idea although theres no way to really know besides getting feedback from what happens.

In some pcm programs ignition is advanced until knock is detected to create the "best" ignition timing. Its in a sense like a oxygen sensor giving feed back to come up with ideal fuel trims. This also allows the pcm to take advantage of higher octan fuels and compensate for poor or degraded fuel.

If you wanted to put a bandaid on top of a band aid id recommend getting an aftermarket knock sensor to monitor whats going on. Some even have peak settings that can notify you when you've reached your set threshold! I forget some of the products out there i believe...safeguard makes a pretty good one?


GOOD LUCK

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neverlift
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Re: Help with Code 34 - Knock sensor!

Postby neverlift » Thu Feb 23, 2012 8:07 am

yeah the 1k ohm resistor trick will help.

you buy shield at the parts store...
besides the knock sensor is a one wire deal the second wire on the plug is just shielding...


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