check engine light. knock sensor and injector circuit

[94pathfinderrr]

So I found this forum when looking up how to manually check my check engine light, thanks guys

 

But now I found it's throwing codes 51 and 34. Knock sensor and Injector circuit.

 

Where do i go from here? The car runs rough when the light comes on, but fine otherwise. I have rebuilt fuel injectors, like 6 months old.

 

Is the knock sensor going off because of an injector problem? Or is the knock sensor broken and need to be replaced?

 

Please i could really use some advice, this is my only car and i'm lost without it

[Precise1]

Hey, welcome to NPORA.

 

I have not had this problem myself, but from what I understand the knock sensor code can be triggered by many other failures. It is quite likely you have an injector failure that is the culprit. I do not know how to trouble shoot the knock sensor, but I recommend looking at the top here in the Garage Section in the Factory Service Manual thread and download your own copy, it can be invaluable.

 

I had to troubleshoot injectors on my wife's R50 and I was able to find an injector that was intermittently failing (only when hot after the motor was restarted) by checking the resistance (4-12 ohms or something like that, it's in the manual) so keep that in mind too.

 

B

[XSrcing]

IT sounds like you have an intermittent short or ground in one of your injectors causing it to either stay closed or get stuck open. Both of these will cause your oxygen sensor to read way out of it's normal range causing the ECU to think there is a fault with it.

 

I couldn't tell you if it was getting stuck open or closed without knowing the O2 sensor voltage while it is happening, though.

 

If the voltage is high (.9-1 volt) then an injector is stuck open. If the voltage is low (0 volts) then an injector is stuck closed.

Edited January 11, 2011 by XSrcing

[94pathfinderrr]

okay so i'm currently limited to tools at my disposal. but i changed my oil, added some fuel injector cleaner and topped my tank off with premium gas and reset the ECU.

 

the error codes are gone, but now the check engine light blinks whenever i press the gas peddle. So i'm thinking i either have a fuel injector stuck open (exhaust is blueish and i'm burning thru alot of gas) or my TPS sensor is fskced up

 

but i when i go into diagnostic mode now i cant retrieve any codes, it only comes on when i press the gas.

 

and ideas?

[Channel595]

if the cel is blinking it will hurt the cat more then the engine. as far as injector cleaner goes i have seen most of it do more dammage then good to the seals. check the wires to see if the insulation is cracking off

[94 Pathy]

I'm telling you right now.....If it's the knock sensor, do a relocation of the sensor so it's easier to replace & get to if you need to replace again. I didn't do it with mine that I just replaced last month, but wish I had the time to do so. I found a spread & guys are relocating it to the top of the upper plenium. You get from the Nissan dealership a wirelharness extension for like $30-$35. I'll try to find it again & add the link/info to this forum. Saves ALOT of headaches.

[94beast]

hey im having quite the same problems with my 94se. the only difference is that mine is marking the knock sensor and a leak in a injector. so i went along and took the heads off and did all that and my knock sensor was melted due to, to much overheating.. so i just went along and bought a new new knock sensor and all 6 new fuel injectors. i later then found out one of my heads were bad cause i took them to the machine shop and its what they told me.. so now ima put briefly about 1200 dollars in work.. but once im done putting everything back together ill get back on and let you know how everything turned out... so i say check your knock sensor make sure its still good..

[kefferjoe]

So i had this problem when i first picked up my pathfinder and i simply disconnected the battery, i called the dealer to see what it was and he simply said that if it receives for an instant a wrong code that it could set this thing off....before doing anything expensive i suggest unplugging your battery for 15 min and trying it again.