Knock Sensor Replacement...did My Own!

[Chriskaw440]

I finally dove in and did the ol' headache of replacing my faulty knock sensor on my 1990 se. Let me tell ya, for the average wrench turner, it was quite a project at times. While I had the manifold and plenum off, I also replaced the valve cover gaskets and ALL hoses, both coolant and vacuume since some are impossible to get to unless you remove the plenum.

 

Hardest part was putting all the electrical wiring back in the same place and the TWO LITTLE DAMN COOLANT LINES that run under the plenum where they connect at the very back. Pain in the butt and I wanted to slap Nissan around for that design and for putting the AAC valve UNDER the plenum instead of to the side or thereabouts, like on most other cars. If it goes bad, you have to remove the plenum to get to it. Lame on nissans part again.

 

Over all though not too bad for a first timer going that indepth into engine repairs. Also replaced the O2 sensor (thank you nissan for NOT putting a connector down by the sensor so you dont have to reroute all three or four feet of wiring again over the transmission...again like most other vehicles have)

 

Codes are all clear and she purrs like a kitten now, not bad for 239,000 plus miles. Overall cost, about $320.00 as opposed to over a grand that most any shop wanted for the labor and thats not including new O2 sensors and hoses and soforth. (knock sensor was $139.00....LOCAL NISSAN WANTED OVER $240.00 for the same one I ordered online for 139!)

 

PS....upon removing the valve covers and seeing all the GUNK/CRUSTY oil build up on the inside of the covers and on some of the rocker arms.....Im going all synthetic....even the best conventional oil didnt impress me in that department.

[88pathoffroad]

AFAIK you only have one O2 sensor.

 

Good to know, did a bad knock sensor cause idle or drivability issues or did it just annoy you with the CEL?

[Chriskaw440]

AFAIK you only have one O2 sensor.

 

Good to know, did a bad knock sensor cause idle or drivability issues or did it just annoy you with the CEL?

 

Yes thankfully this year (1990) only has one O2 sensor before the cat. Mine was probably the original one too.....

 

My model does not have Check Engine Light on the instrument panel, its the old school "red light and green light" on the ECU

flashing codes. "34 - knock sensor" been like that for years too.

 

For me, it caused knocking if you used any gas less than 93 octane, since it couldnt adjust the timing when knocking/pinging would occur.

 

Now it seems to be running at a much more efficient peak....and a lot smoother.

[Mr. Pickles]

Congrats on the replacement. You're lucky, when mine went, the truck was all but non-drivable. It simply would not idle at all, and barely ran under throttle. Had no garage and lived in a townhouse where the HOA nazi's threw a fit, so I had to pay like $500 I think to have it done. Good job.

[Chriskaw440]

Congrats on the replacement. You're lucky, when mine went, the truck was all but non-drivable. It simply would not idle at all, and barely ran under throttle. Had no garage and lived in a townhouse where the HOA nazi's threw a fit, so I had to pay like $500 I think to have it done. Good job.

 

thanks. It really was my biggest engine repair undertaking I have ever done. Just took my time and replaced all the common sense items too while the top half was all out....be silly on a vehicle that old to do JUST the sensor and not all the hoses and vacuum lines, and clean out the valve covers and replace their gaskets too.

 

Funny thing I found during this job, I think its called the "oil breather tube system" that runs from one valve cover to the other along the front rail, just above the AC belt tensioner assembly.....when I was putting it back on and decided I should replace the short hoses on each end too, I noticed there was something inside the tube! so with needle nose pliers I reached in and extracted a section of a WIRE BOTTLE BRUSH, that apparantly had broken off and was left inside the tube, I assume by the previous owner at some point (I'm the second owner) so its been in there for over 5 years if not more. I didn't think it was a true NISSAN part LOL. Hopefully now the valve cover breathing system will work more efficiently.

 

The local NISSAN/IMPORTS shop here, the best in town too, wanted about $1000.00 to do the job and since it was still running good even with the bad sensor, they suggested just leaving it be until things get worse.

 

I hear some trucks just go to running like crap when the knock sensor goes out but some, the ECU goes into a baseline mode just to keep it running and then flashes the code "34"

 

Next project, Shock Absorbers...at least those are easy

[Dannyg]

 

 

I hear some trucks just go to running like crap when the knock sensor goes out but some, the ECU goes into a baseline mode just to keep it running and then flashes the code "34"

 

 

My 93 pathfinder has been running rough for the last month and in the mornings when its ran for the first time of the day it runs smooth but once it warms up its sputters bad. Like its running out of gas but it mever dies on me. Its idles sort of rough but i also get the knock sensor code. Could a bad knock sensor cause those symptoms and by replacing it would it fix the sputtering ??

[Slartibartfast]

I haven't heard of a knock sensor failing only when warm. Also, however much the ECU detunes the motor when the knock sensor thinks there's a problem, it shouldn't be making it sputter.