I'm having technical difficulties with my car. At a little before 3,000 rpm, I'm hearing a sound very similiar to valves knocking. after about 3,500 rpm, the sound goes away. If I'm on the car really hard, it will continue above 3,500 intermittently. I've always run 93 octane. My only idea know is to change my oil from 10w-30 to 5w-30. Anybody have any answers to my problem? Any advice would be appreciated.

 

I dont know if this is your problem, but replacing the fuel filter can cure any stumbling.

 

I replaced the fuel filter about 9,000 miles ago, but I replaced it with an Autozone fuel filter. I have a feeling it needs to be replaced because my performance has noticablely dropped and my gas mileage went way down south. I used to get about 360 miles to a tank, but now I'm lucky if I get 260. This has all happened within the past two weeks or so. I'm going to go and pick up a new fuel filter from Nissan either today or tomorrow and replace it.

 

Shot in the dark. Test your coils, your plugs, your compression, and get your injectors cleaned.

 

Wild guess: the sound you are hearing is engine ping and the cause is an EGR valve which is opening too late or EGR passageways which are obstructed with crusty deposits.

 

Is there anyway to fix this problem myself? Should I take the EGR system apart and clean it with some sort of solvent? If the EGR is opening late, wouldn't that signal the ECU that the part isn't functioning properly. I don't have a check engine light. Just taking guesses. Let me know if I'm thinking straight. I'm appreciating everyone giving suggestions. Keep them coming.

 

Exhaust Gas Recirculation system and component testing is covered in the Chilton repair manual (page 4-10) and the Haynes repair manual (page 6-19).

 

I can scan those pages in the Haynes manual if you dont have it. Send me an Email address and I'll do it tonight when I get off work.

 

I've got the Haynes manual. I'll look through it and get it cleaned. I appreciate you offering to scan those pages for me, though. I will let you know if it fixes the problem. I really want to thank you guys for the help. I'll keep you posted. Thanks again.

 

I was due for routine maintenance, so I just went through and changed spark plugs, fuel filter, PCV valve, and changed the oil. I also tightened the accelerator cable because there was way too much slack in the cable. When I got all of that done, I went for a test drive and the sound was gone. I want to thank all of you for your help. I was quite surprised at how easy it was to get all of that done. The hardest part was trying to get the fuel line off the fuel filter. Anyhow, thanks again for all of the help.

-Josh; no more noise!!!