Ok I've already posted this, but my problem got worse. I have a constant knocking sound from the engine that can only be heard at idle. I've searched and couldn't find anything usefull. I don't want to have to pay Nissan $75 just to tell me whats wrong. So if anybody has any thought or ideas, please let me know. Thanks.

 

How about a little bit more information? Year and model of the car? How many miles? Heard only when starting up the car at idle, or anytime during idle?

And also post the problem in the topic: "Knocking heard during idle", not "I'll give it one more try."

 

also, where is knocking coming from might help.

 

Be as detailed as you can to help us out on this one. That way people can figure it out easier for you.

SuDZ

 

Allright some responses . I got a 98GXE 5spd. The knock is only heard at idle when the car is warmed up(the rpms at about 600). You can hear it inside the cabin only if there is no outside noise. With the hood open you can hear it good. Sometimes when you're outside close to the car. It sounds like a hollow banging sound comming directly from the engine. First you could only hear it when the headlights were on. Now it's there all the time, with the above conditions.

 

i wonder if its detonation? but that is more associaed with ping than knok, or you could have something loose which would really suck

 

it can be two things, your valve, something loose, and your OIL. use synthetic oil.. try that first. your valve may be loose. its kinda hard to explain..

 

I don't think that I should be forced to use synthetic just to have my car run properly. Thanks for the help though.

 

Use a "mechanic's stethoscope" to isolate the noise. By mechanic's stethoscope, I mean you can use a length of rubber hose and place one end up against your ear and the other to probe for the noise. You might be able to find a valve or injecotr that's making more noise than the others or a maybe your chain is making the noise, etc...

 

You didn't mention how many miles you have on the car.

 

yup i agree with ravq, a 1-2 foot rubber hose will find your noise and lead you to your problem.

 

Is your 98 GXE still under warranty?


Anyways, even if you determine what kind of problem it is, when you take it to a shop they will still charge you to figure out what the problem is for themselves. Sucks, but that's how it works. It's even worse with the dealer, who almost never diagnoses anything correctly.

Like others have mentioned above, a knocking noise can be caused by many things. The obvious one is detonation. It should be happening even on regular, but are you running high octane (91+), or the cheap stuff. A lazy knock sensor might not be reacting fast enough to retard timing and detonation.

 

I have 52k miles on it. I always use 93 octane.(its only $1.19 here ). The reason I havent doe the hose test yet, is that even if I do isolate the noise, I'll have no clue what the part it's comming from is. I did the ECU check, and it came back fine.

 

use the hose, you'll be amazed how close you can find where your knocking is coming from. why did you check your ecu if the check engine light didn't come on? seems like you're willing to work and check your ecu but not will to do the most simple and most problem revealing. if you don't want to do the work, take it to the dealer!

 

I also hear metal clattering noise from the engine only at idle and when inside the car if there's no outside noise, like you mention. With the hood open it's more apparent.

I used to think it was the normal valves noise, especially since the V6 has more of them than what I'm used to with the V4. As it turned out MOST of those noises are coming from the fuel injectors opening and closing. I found this out using one of those stethoscopes with a metal ending and by touching it to various engine area I confirmed the loudest metal noise was from these injectors.

Also this type of noise can only be heard when the car is idling since while moving you have wind noise, road/tire noise, and of course your typical engine noise.

 

It's not really clatering noise, It's more like there a midget in there banging regularly on a hollow part of the engine with a hammer. Ok fine you guys convinced me. Now when I go to the Auto store, what exactly do I ask for, in terms of the rubber hose?

 

go to the hardware store and get 2" diameter rubber or plastic hose, about 1.5-2 feet long. you may be able to use an old vacuum cleaner hose.