anyone figure out that knocking noise??

[migs7585]

I was looking for the thread about the noise some of our cars make while slowing down and at a stop...its the knocking type sound coming from under the car in the middle area...someone said something about the heat shield but i wanted to get a conformation on that....anyone kno???

[masterbeatty]

What type of gas are you using because the higher octain level you use reduces that noise. If you always use the cheap sh*! then in time you will develop the knocking noise. But it is acctually from your valve train. There are acctually anit-knock sensors in the engine but they can only do so much if your using low grade crap.

[dldjros69]

Im not sure thats true Master! Be prepared for the rest of the community to jump on you.

Umm - first the 2.5L engine is designed to use 87 using 89/91/93 is not going to give you any added benefit. It could possibly hurt the engine or reduce performance.

The 2 noises you could be hearing have been discussed on there before. 1st could be the head shield on the exhaust. There is an active recall out for this. the other thing it could be is your ABS system doing a self check. Your problems sounds like the first one. My coupe never did this.

[LinkNuc]

Um I don't want to offend but were you slowing down on a slippery surface? That would be the ABS and VDC working together. It exactly sounds like knocking from the middle underbody.

[migs7585]

nah it does it all the time basically at a stop or slowing down. Dont think its the ABS so I think I'm going to have a talk with my stealership. I was using 89 but was getting poor mpg so I went back to 87.

[scannon007]

Ok guys - listen up. I have had my car in the dealership at least 7 times for this problem. They replaced the front pipe twice. Still heard the noise. Each time I went there I told them I thought it was the heat shield. Now I'm just a girl and not a mechanic so they dismissed me. I finally had it after they told me it was a normal noise - we know its not. I went to a different Nissan dealership and guess what? It was the heatshield in the middle of the car that was heating up and popping and hitting the body of the car. They fixed it by putting washers behind the rivets so that the heat shield cannot hit the body of the car. I'm happy to say I haven't heard the noise in 3 days - woohoo!! They should have listened to me a year ago. Tell your mechanics this is the fix. If you need further details let me know. Good luck!!