When I am in low RPMs and usually in a higher gear (i have a manual) a strange "knocking" "rattling" noise comes from the engine bay....A friend of mine told me this was from the injectors and a sign that they needed cleaning. I poured in some Lucas fueld injector cleaner and the noise was gone or wasn't as noticeable for about half a tank of gas. A poured in another treatment with another tank of gas and the noise is less but is still coming at times.

I cannot associate the noise with any kind of conditions....(cold, wet, ect.) Anyone have any idea what this could be and some solutions?? Again, the noise comes when I am accelerating in a lower rpm (below 2,300 maybe). The noise is also the same noise the car makes right before it stalls out (for you manual people out there). It is a sort of "grinding" "clanking" noise....kind of hard to describe. All i know is that it is making me mad and worried....

 

mine does the same thing...i just live with it.

 

Is it a quiet rattling or a loud one? When I hear "rattle" I usually associate it with minor detonation. But that's coming from the supercharger world

 

if he's talking about the same noise, it kinda reminds me of a diesel...its like a quiet rumble that only happens at low RPM under load.

 

yah, basically....


Although it is usually medium soft, once i stepped on the pedal and it was pretty loud....very very noticeable loud. Loud as in someone that didn't have a clue about cars would ask, "what is that strange noise?"

What should i do to fix this.....

Edit: Although now that i think of it, this could be detonation because the Lucas treatment claims that if you use it, you don't need higher octane gas.....and when I have used it twice so far the noise has gone down considerably....

 

yep same here I believe this is called pinging try a higher grade octane gas

only time I get this is under a heavy load like backing up a hill with my 4x8 trailer in the woods also usually only dose this if the motor is hot for me

 

well, isn't there anything I can do to prevent it from pinging other than using high octane fuel. I mean the specifications say to use regular. Why is there early detonation occuring? Shouldn't the ECU advance/retard timing automatically?

 

Could it be something with my spark plugs or anything else that I can replace/check.....? Its been going on for some time now to.... Isn't pinging also harmful for the engine?

Sorry about all of these question pouring out at once but I just want to do something about it.

 

I had been hearing a very similiar noise. I tried for months to pin point the noise. I even thought it was something loose or rattling in my header/exhaust.

anyways, about two weeks ago i decided to pickup a k&n drop on air filter, new spark plugs, and some seafoam.

To be honest I believe the seafoam fixed my problem.

 

i have the same noise and always have. seafoam didnt do anything for me. i havent tried to fix it or anything other than the seafoam

 

If you're issue is indeed pinging, the most likely reason for the occurence is heavy carbon build-up. This effectively decreases combustion area, proportinally increasing heat and leading to premature detonation. The fact that carbon likes to glow red hot doens't help much either in there.

Seafoam is usually a real good treatment and just running higher quality gas helps tremendously. I know it might be hard to believe, but running a supercharger, the differences between 91 flying j and 91 chevron are HUGE.

 

i had some pinging too but i had 80k miles on my fuel filter and spark plugs. plus 80k miles worth of gunk and carbon build up. seafoam (2 in the tank and then 1 in throught pcv valve), new regular denso plugs and new fuel filter i havent heard it ping...... sometimes you get bad gas somewhere and you get it.. try getting the same grade fuel somewhere else like bp, exxon or some name brand and see if that makes a difference and work up to buying plugs and etc..and deff do the seafoam! perhaps also take the intake tube off and spraying some carb\injector cleaner in there.. how many miles do you have on the truck?

 

Detonation or Pinging bad stuff
could be carbon build up.
do the normal tune up stuff, make sure everything is to spec and use some premium fuel

 

I have around 112,000 miles on it...I bought it at 108,000 miles around november and its been doing it since then as far as I know....I usually fill up at the 76 station or Shell by my house....

I guess I could do a search but does anyone have a picture of the PCV valve as i do not know what in the world that is or where it is located....also are there any "chain" stores that carry Seafoam?

 

NAPA and Schucks carry Seafoam.
I have the same pinging noise and I would also like to know about where the PCV Valve is so that when it's gets above freezing up here in a month or so I can try and run some Seafoam through my truck and replace some wires.
Thx in advance.

 

Hi,
this is an old post but the solution is important to so many, so I will respond.
Had the EXACT same issue around 80K after using fuel injector cleaner....Killed my allready old/aged spark plugs

I'm 110% sure its your older sparkplugs......
FINAL ANSWER?
YES
MY FINAL ANSWER!
To other who have had this issue solved..... its wasent carbon or fuel injector cleaner that solved this issue as soon as you decided to replace your aged spark plugs,that did the trick!
again it is your OEM plugs that are supposto be replaced every 30K!!!
Please trust me....
If you add seafoam or techron cleaner to these older plugs you will foul them badly and make the detnoation much worse.
AND YES THAT NOISE YOU HEAR IS 100% HORRIABLE for your engine and you need to replace the plugs right away....

good luck and god speed everyone!
over and out!

 

I have the same noise too. When accelerating at low rpms under load (not pressing the pedal enough for the auto to switch gears), the engine makes a marbles in a can sound. I've always maintained my engine well so I'm not sure what it could be. I have a new Toyota air filter, new NGK factory replacement spark plugs that are pre-gapped, new NGK spark plug wires, throttle body and MAF sensor cleaned and it still makes the marbles in a can noise (I also sea-foamed it before changing the spark plugs). Going up to 89 octane helped a bit, but this feels like a bandaid solution covering up another problem.

The next thing I will change is the fuel filter. I'm stuck too regarding this problem.

 

i've got new plugs too and have the sound, I believe it is valve chatter...i'm not sure what the fix is, i don't think the valves are auto-adjustable, I've got to do a timing belt change soon so may have the valves looked at then....I could also be totally wrong....i'm going to try and record the sound it makes and post the vid here, it doesn't do it all the time and doesn't last long so I may have a tough time getting the camera ready

 

I may be way off base on this but is it possible that if its a rattling noise that it could be an exhaust heat shield or something along those lines. I have a slight rattle under minor acceleration and that is what i have come up with.

 

It sounds like a gear rattle in the manual tranny.Do you have a manual?If so shift at a higher RPM.