About two days ago I started hearing some engine knocking. It seems to get worse as the car heats up and It generally occurs upon acceleration, or revving. I recently have cleaned my maf and throttle body and today I put Fuel injector cleaner in. I use 87 gas. My car is just under 110K and its a 2002 se. Im really scared as to what this could be. It doesnt do it much when the engine is cool. Also it seems that the warmer the engine gets the more slugish it gets warmer...possibly bad timing? Is it safe to drive it with this knocking? Any insight would be greatly appreciated.

 

my guess is it's the 87 octane gas... you should be using premium which depending on your altitude would be between 93 and 91 octane

 

I'm hoping its the gas. I just filled it yesterday, but I put the fuel injector cleaner in today. maybe im mistaken but doesn't the injector cleaner act as an octane booster? Thanks for the help so far I really do appreciate it.

 

it may a little but you definitely need to stop using low octane gas otherwise you could cause some serious problems with your engine

 

okay I will def start using at least 91. I cant be cheap any more lol. My other guess is that it could be a belt. I just had a belt replaced so they might have installed it incorrectly.

 

it is about 6's anyway with using premium gas... you will get better mileage, performance and you will reduce the risk of pre-detonation which it sounds like is your problem

I really doubt it is your belts they tend to squeal when they are causing problems.

 

alright. well is it still safe to drive? should I have the fuel system flushed?

 

Definatly use super it's only like $3 more per fill up and it will make your engine run much smoother. Remember to only use top tier gas ie. Shell, Texaco, Cheveron etc. Don't cheap out and buy from discount gas stations. It may take a few tanks before it goes away but it will I'd recomend Shell V-Power I had some slight knock from using discount gas stations 93 and after 1 1/2 tank it was completly gone IMO its the best gas.

 

I don't see the need to do that at this point but i would pick up some octane booster, i'm not sure if it really works or not but it can't really hurt at this point. I would also avoid the activities that result in knocking (revving and hard acceleration). And from now on use good gas...

 

is it safe to mix the octane booster with the fuel injector cleaner? I just put the injector cleaner in today. also just clarifying after viewing some youtube videos most people with knocking had it constantly when the engine is on. mine is just if I rev it and I acclerate more then half way(especially up a hill)

 

fill up with premium as soon as possiable.

 

You probably only hear it under load because at idle the engine can retard the timing enough to elinimate it but under load it's more promenent because the ecu can't retard it enough to eliminate it without massive power loss.

 

Dont waste your money on octane booster it's not enough it only raises the octane by one tenth of a point if you read the bottle it will clearly state this 5-7 points = .5-.7 increase not enough to help.

 

As long as what you are hearing is pinging (pre-ignition), then adding some octane booster then using premium (says right on the gas tank door to use a minimum 91 octane) gas should get rid of the noise. If you are hearing a heavy knocking that is coming from the lower part of the engine, that could be a bad rod bearing. From the timing chain side of the engine, odds are it is the tensioner.

 

so im stuck then. I guess all i can do is burn up this entire tank of gas. ill do some basic local driving and ****. then once it starts to go down I guess ill put the premium in it.

 

what does pinging mean? this is exactly what I hear if my car is in park...

engine idles as normal give it gas, it revs , right after rev I hear a rattleing noise that I assumed would be defined as knocking. Also when driving up a hill the rattle comes back on once in a while. this generally only occurs when the engine is warmed up. the sound almost resembles throwing a bunch of rocks on the ground. Its brief yet noticable

 

If the car is simply pinging (sounds sort of like BBs in a can rattling), it won't do it in park or neutral, only in gear and under load (accelerating or going uphill). Sounds more like timing chain/tensioner rattle to me.

You can add octane booster to your current gas, that should help if it is pinging.

 

i took it to a local mechanic to get checked out and he said its my catalytic converter off the y pipe...he says it would be 799 for the converter and then 300 for maintenance. For some reason i'm feeling that he's full of complete ****. He said that i can drive the car like this until I come up with the money, it shouldn't give me a problem, just an unpleasant sound(as it is now)

does this sound right to any of you guys? could a catalytic converter really be making this noise? Also a friend of mine said that he could have his buddy weld on a pipe and just use that instead of a cat converter. He said he would also have it inspected for me so that she will pass.

 

If it was your cat you would definatly have a CEL I guess it's possible the cage the holds the material inside the cat could have a hole and pieces could be rattleing around in there but it seems unlikely as for the price $700 seems right for an OEM cat but can get a fastcat from Cattman for much cheaper and $300 for labor is outragous 4 bolts and it drops right out (plus 02 sensor) labor shouldn't be more than like $100-150.

 

Local high performance muffler shop here wants $300 for a high flow Random cat and $125 for installation (has to be right to prevent future SES lights).

Your buddy is looking at a $10,000 fine if he gets caught removing a cat and installing a test pipe and then passing you. Just FYI.

 

thanks for the info. Im actually taking the car to the stealership to see what they say. Couldn't hurt they said they'd check it out for me for free. Something is just telling me that its not the cat because I dont have the check engine light or anything. My instinct tells me that it's a loose heat shield from when I got in my accident a month or two back.

 

are there any good online places where I can get that cat?

 

Blitzfist, don't spend any money on your cat, change your gas. I was one of those guys who didn't think using 87 octane was bad for the Max since I used it religiously in my 97. I used 89 octane in my 03, added two bottles of octane boost and still had pinging.

Well this past Saturday I filled up with 93 octane and drove it out on a visit to my moms house over 200 miles away. I filled up again twice more on 93 and guess what, no more pinging?

Btw I did read the manual and it does say that 87 can be used but that it "may" cause poor engine performance. So I would now recommend using the highest octane gas you can afford. Good luck and I hope this fixes your problem.

Quick note: my last two fill ups of 91 and 93 octane cost me $48.24 @ 3.699 a gallon and $52.84 @ 3.669 a gallon.

 

Not lonly run better gas but I always get it from shell or exonn. Not sure if there is any real diff, but in my mind there is. Plus I have not had any more noises coming from under the hood...

 

Recently I had fill up with a full tank of regular, due to no other options. I ran through a full tank and now just filled up with 93 at Chevron and also added a bottle of Techron to the tank. This sound is considerably amplified when I shift or decelerate. Could this be due to any other engine issues ?

 

I had my car checked out by nissan and it was both low octane and a bad secondary cat. The guy said the cat does not need replacing, but there is something rattling around in there probably from when I got into an accident. I'll just live with the noise for now and then eventually pick up a cheap magnaflow converter and have it put in.

 

dude i had that problem and hollow the cats out quick because if the car gets no much back pressure then it will cause serious problems