I have a '95 with auto trans......When accelerating lightly when the rpms get to about 3000-3500 the motor starts knocking until it changes gear, then does it again, and again through the gears. I notice it more when it's hot outside. It's driving me crazy!! I've replaced the spark plugs, got the injectors cleaned by the dealer, cleaned the air filter, and I've always used 93 octane since it was new. Nothing helps.
The check engine has never come on. It also seems kind of sluggish.
Any ideas???????
Thanks

 

check for codes, i bet ur knock sensor is shot!

 

check if your knock sensor is dead...
also, when it is misfiring, it should throw a code to the ECU and set off the CEL. this will tell you which cylinder is misfiring. then you can focus on that by replacing the ignition coil or seeing if the plug is fouled.
i don't know what cleaning injectors does...when it dies...its dead...just replace it.

 

If it was throwing codes, wouldn't the check engine light come on?
Also the old plugs looked perfectly normal.

Like I said before I only notice it when it's hot outside. It idles perfectly smooth, and revs fine. Can't hear the noise unless accelerating.
Possible knock sensor, huh?

 

no for the millionth time (no offense) the knock sensor code is a ghost code, it will NEVER trip the check engine light

 

Ohhhhhhhhh. cool, I'll check for codes.
A bad knock sensor would cause these symptoms?
I know it's never been replaced, and the car has 128,000 miles on it.

 

Yes a bad Knock sensor will give you theses symptoms. You will surely have a 0304 code.

 

a misfire code will flash the CEL temporarily...then go away
you have to check and be sure

when's the last time you changed your plugs? even if its not the problem, its probably a good idea to get them changed if its been awhile.

it doesn't sound like your knock sensor is dead, but check for it anyways...the symptoms of a dead knock sensor is the retard of timing and thus poor performance of the car.

 

AnGe's car pinged similar to that last year and never threw a code.
It turned out to be her coils.

Our ECU isn't perfect, don't expect it to always know whats wrong.
Thats where the org comes in handy

 

Did the coils test bad with a multimeter? Or did she just run out of ideas and start replacing coils?

 

If the knock sensor is bad and the car is still knocking with 93 octane gas, then you have other problems, not just a bad knock sensor. When the knock sensor goes bad the ecu reverts to a default mode where the engine timing is retarded the maximum amount to avoid detonation.

One thing that can cause detonation is an intake vacuum leak. An intake leak results in a lean afr which makes the engine susceptible to detonation, especially on hot days. The fact that the car feels sluggish can be due to a bad knock sensor, but it can also happen with a working knock sensor that has pulled timing as much as it can because of the detonation.

 

I don;t know if this is it, but have you checked the fuel pump? And for general maintenance, change the fuel filter.

 

The fuel pump comes on, and the fuel filter was replaced about 3000 miles ago. The injectors, and intake manifold were cleand by a Nissan tech about 3000 miles ago. The plugs were replaced about 2000 miles ago, none of the old ones were fouled. The knocking has been going on for a couple of years, but like I said it only does it when it's real hot outside. When it's cooler out, it seems fine, and I forget about it until summer.
Can somebody tell me the sequence of events to check the codes by using the check engine light? I Just moved out to CA from FL. Our house hold goods haven't arrived yet, and my service manual is packed up with everything. I did it a few years ago, and it seems like you got to turn the key on then off, put it in neutral, back to park......let air out of the front left tire,etc,etc.
The car is a '95 GXE w/ auto trans.

 

Check the top of the 4th gen forum. There is thread about the check engine light. It will tell you how to get the codes and how to find out what they mean!

 

Hey thanks.....I just went out to check the codes, and I got 0304.
Looks like the knock sensor!!!
Now.........since my service manual is packed up in Florida....how hard is it to replace it? Seems like I remember it being below the intake manifold??????

 

Hold on a second. The 0304 code is set when the signal from the KS is out of it's acceptable range. If your hearing the knock, it could be so excessive that it's indeed producing a signal from that sensor that is excessive. In other words, the KS could be working and alerting you to the fact that you have excessive knock and ping.

Clear the code from your ECU, dive around for a day and try to avoid making the car ping. (might be hard to do) See if 0304 comes back. If it doesn't, then your KS is good. If it does come back immediately, then chances are your KS is indeed bad.

Ben - I believe her mechanic found the bad coil(s) and replaced it/them.

 

I agree with this, but I would add that a bad knock sensor will not make your engine knock or ping (especially if he is using 93 octane gas), for the reason I mentioned earlier. Something else is not right with the engine, and that is what is causing the knocking.

Replace the knock sensor if it is bad, but that is not the source of the knocking.

 

locklear Check out these sites

The dealer wants $168
If you want to get it on-line heres the site http://cgi.ebay.com/ebaymotors/ws/eB...tem=2426114287

Theses sites will give you an outline on how to do it http://www.skippynet.com/maxima/knocksensor.htm
http://www.motorvate.ca/mvp.php/507

Just did mine
Hope this helps

 

You might want to think about checking your EGR system. If it is blocked or not operating properly, then cylinder temperatures can rise and cause knocking.

 

When resetting the ecu the directions from the 4th gen section say turn the screw clockwise wait 2 secs then counter clockwise x 2. It doesn't mention doing this with the key turned to "on" or off. Any ideas? I did it with the key on, and now 0304 is gone, and I get 0505, which says no failure recorded/detected. I assume I did it right??

 

You did it right. That's how to clear the code. If the knock sensor (or its circuitry) is bad, 0304 will come back.

 

Run some fuel system/injector cleaner through a tank. Chevron Techron heavy duty will work. Detonation should go away. If not, try again. Had exact problem, fixed it. Injectors are dirty, and engine is running too lean, causing detonation. Computer cannot compensate.

Put a can of Techron in tank every 10K or so to avoid this problem.

 

I just had the injectors cleaned by the Nissan dealer, which they hook up some kind of machine that cleans them........the knocking was still there afterwards.

 

Still, give a can of Techron and a tank of gas a try. Did they clean out the throttle body?

 

Yeah they cleaned out the throttle body, and also put a can of BG cleaner in the gas tank, which according to them is good stuff. It was all part of their injector cleaning package. I've never really looked around, but I've only seen BG products at parts counters at Nissan dealers.
I'll try a bottle of Techron.......which one? There's a few different ones I think. Like complete intake system cleaner, fuel injector cleaner. Which one worked for you??

 

I used the heavy duty fuel system Tecron to clean it out. Then I use the cheaper injectopr stuff to maintain the system.

Give it a try, see if it works after a tank of gas. It's cheap fix if it does.

And, it could be the EGR, as other have said.

By the way, you do stomp on it and blow out the carbon once in a while, don't you? I've noticed after a long freeway trip, without getting on it, my engine loads up, and develops a slight ping. Once I floor it a few times, the ping goes away.
When my high-compresssion 289 Ford engine loaded up, I would drip water into the carb at high idle. This blew the carbon out, and ended the ping.
This engine is just prone to pinging and detonation when everything is not perfect.

You might want to pull a few spark plugs, and see if the color is good if other things do not work.

 

Thanks...........i'll give it a try.
After resetting the ecu, the knock sensor code has not come back, but it's only been about 20 miles or so.

 

This may not be it but check it out anyways.
Go to the Chilton's online manual:
http://www.cybrrpartspro.com/Manual%...delLookup.html
- select the year and model
- select "Maxima (4 Door)"
- click on the TSBs & Recalls on top of the page-
- select "Fuel Sys, Driveability, Filters (Air & Fuel)"
- click on "07/31/1996 - SPARK KNOCK - A/T W/ FED EMISSIONS - PCM" & read

 

I may have to take it in to get checked out for this.
I just got some Techron complete fuel system cleaner. I'll try this and see if it goes away......if not, to the dealer it goes!!

 

I know this sounds like it's from out in left field but run a new ground to your air flow meter.
It takes about 6 inches of wire and a 25 cent splice.

I was having similar problems with my 95 when it got hot outside.
I tested, fixed, or replaced everything I could think of including the KS. Problem gone after new gnd wire installed. Gas mileage went from 18mpg to 22mpg in town too!

 

Where is the exsisting afm ground wire? Do I run a new one off of it? Or do I run a new one from the afm, along with the exsisting one?

 

Same thing is happening with my car! Cylender 1 Missfire, with ks code going off, What is causing this, I tried the Techron crap, Im fed up with it, There is like no power when I floor it anymore, I just past 50k a couple days ago? what is it thats causing this?

 

Bad injector more likely than a coil.
Check it with an ohm meter, if it's somewhere around 10 ohms you're good. If it's over 15ohms or you get no reading or "infinite" resistance (which is actually OPEN).
An OPEN injector is BAD.

You have to replace it.

 

Like a really quick flash?

I was tuning the AFC today and ran it slightly on the lean side and I think I saw it flash out fo the corner of my eye at 5800 RPM in 2nd Gear.....

 

could bad or no-properly gaped plugs cause a KS code, i have noticed a extreme losss of power but im not sure what it is, how can i check my Ks without taking it out? my car also smetimes throws the MAFS code.

 

I am with regbike. Ask the mechanic if he cheked the egr valve. Will cause knocking if bad.

 

Or just stick your hand under the valve on the diagpram and rev the engine and see if it moves.

There is a picture of the valve in the picture below - you want to feel underneath it for the diaghram then see if it moves up/down when revving the engine.

 

How long does it take for the Knock sensor code to come back after re-setting? If it is bad, will it come right back on, or does it take time? I'm getting the code again, but it didn't come back until about 40 miles after re-setting. During this time I drove the car nice and gentle, and did not hear any knocking. Bad????

 

how much would it cost to get this done @ a dealer? Is it covered under warranty? I have an extended bumper to bumper