Lately my car hasn't seemed to be its ole self. Since my check engine light never seems to come on when a problem is found, I did the diagnostic on it tonight. I came up with a Code 34 which is the knock sensor.

I will start the troubleshoot procedure tomorrow but has anyone had this code before? If the knock sensor gives a trouble code, does the ECU do anything to decrease performance i.e. a bad coolant temp sensor,etc.

Thanks for any comments,

Steve

I beleave it will go to limp mode. Don't quote me on this cause I'm really tired now. My FSM is at the shop:(

Well for those interested, I followed the FSM and checked continuity between terminal B of the knock sensor connector and Pin 27 of the ECU harness. All good.

I then checked terminal A and a engine ground. Nothing. I guess that means its time to replace the knock sensor after 210,000 miles.

Steve

hey Steve, I'm having the same problem as you and my turbo doesn't hold boost anymore because of it( I think??) Anyways, exactly where is the knock sensor located? (I know it's in the back of the block somewhere but I dont know what exactly I'm looking for)
Thanks,
Nick

Well it is a small black round looking thing with a bolt throught the middle of it and a plug on it. You mite have to take the starter off. Mine is broken on my bb and i have the motor out so i guess i should replace it ? lol

Originally posted by muleman
Well it is a small black round looking thing with a bolt throught the middle of it and a plug on it. You mite have to take the starter off. Mine is broken on my bb and i have the motor out so i guess i should replace it ? lol

Right, what he said. Except you shouldn't have to take the starter off. Its located a little to the right and a little higher than the starter if you are on your back and looking up at from the ground. Its a little bit tight in there but not that big of a deal. The connector points to the passenger side.

Steve

Thanks guys, I'll be taking a look at it later today.

A knock sensor from a ga16 and ka24 is the same, and probably most other Nissans will work also. It was said before, but definitely check continuity on all the wires. I had the same problem and it turned out I had tightened the bolt on the harness to the ecu too tight. This pulled the outer most portion of the connection just enough to loose continuity. Loosen the bolt a little and push the ends down. If that isn't your problem borrow a friends ecu, it might be that. Good luck.

and I am getting a code for Cylinder 1 misfire, and multiple cylinder misfire. I am not noticing any misfire, spark plugs are new, spark plug wires are new and the injectors are ok. Will a faulty Knock sensor cause these mis fire codes? Approx how much is this sensor? Thanks!

1. The knock sensor will not cause the car to go into limp mode
2. The knock sensor has nothing to do with boost, all it does retard the timing when it senses knock or detonation. The boost is controlled mechanically by your waste gate. All the computer sees is the amount of air sucked in through the MAF and gauges rough fuel calculations based on these readings. Fine tuning of th A/F ratio is done by taking readings from the coolant temp sensor and the tps in open loop, and the o2 as well during closed loop.
3. The knock sensor will not cause cylinder misfire codes or multiple cylinder misfire codes, you have another problem.
4. The knock sensor, when it fails will NOT illuminate the MIL light on obd1 vehicles. It will illuminate on obd2 vehicles but not all.
5. The only time you will notice any performance decrease is under high engine load and temps (unless you are using sh**** gas)and usually in the mid rpm range.
6. Little known fact(gained through experience): the knock sensor has NO effect on timing maps above 5000 rpm.(Documented) Engine vibration is too great above this rpm to get an accurate reading.
7. Do not under any circumstances drop the new knock sensor on the ground from any graet height. You will render it useless.

Spark plugs and wires are new, compression is fine, and injectors are working properly......where now?

Cap and Rotor?????

Thanks for dropping great knowledge David;) you said that the AF ratio is tuned by readings from TPS, coolant and O2 sensors so if either one is bad, could it cause a boost problem only and no other problem or symptom while the car isn't boosting?

probably not. If the turbo is not holding boost, you either have a vacuum leak (or boost leak), or in all probability, your wastegate is not functioning properly. The REAL turbo guru's can correct me if i'm wrong, but gleaning info from old threads leads me to believe this is true

I've been digging info and I think you're right on the money David. wastegate and vacuum leaks are the most common culprits for boost issues. I'll be checking it out as soon as i can.
Thanks again for the great advice,
Nick

Talking about Knock Sensor

Let me begin my story

Ok first when i install my S4 cams, my car ran like a beast, and a week later my car feels slower and slower. The people that i beat before keep kicking my ass. I didn't know what was wrong with it.

My car was mis-firing between 2500-3500 and after 5500RPM the engline is not making any power.

Finally my motor blew up on me. I blew it cause of overheating the motor and melted the Knock sensor off. and that was why my car ran like shit cause of the knock sensor retarded the timing.

sorry about your motor Thomas, so did your engine blow due to retarded timing from the melted knock sensor? or did it overheat and went kaboom

Andreas Miko told me that i overheated the motor before and melted the knock sensor off.

Stupied me that knows the Radiator have a crack in it and didn't bother to replace it, in fact just add water in everytime.

Than one day i forgot to add water and my motor went boom.