Slight knocking sound at idle

[irrompible]

Hey guys

I have a slight knocking sound at idle. It speeds up as you rev the engine, but you can't really hear it over 2500 rpm. I took it to the dealer a few months ago and they claimed it was caused by the high pressure fuel pump and it was normal. Can anyone else with an MS6 or MS3 verify this noise for me so I stop worrying about it.

 

[MS6 4 Lyfe]

i had a knock that u can hear but it didn't sound like a rod knock it was just a tap an i could hear it from inside but when i stepped on the throttle a lil it just kinda went away but wen i let the throttle go it came back i don't know it was weird but Mazda dealers put a new motor in an its not doin it..does it sound anything like wat i just said?

 

[spanxxxdyer]

I just did the internals swap on my high pressure fuel pump, I can honestly say that it is a noisy little bugger. So noisy that I thought I had put it together wrong.

If you take off the plastic intercooler cover you can hear it much louder than when the cover is on. When the cover is off you can put your finger on the pump and feel that the knocking sound and the vibration from the pump are happening at the exact same time.

Like mentioned as you rev up the engine the sound smooths out, but it comes back louder when the car is idling.

I wouldn't worry about it - that's my $0.02

 

[irrompible]

i had a knock that u can hear but it didn't sound like a rod knock it was just a tap an i could hear it from inside but when i stepped on the throttle a lil it just kinda went away but wen i let the throttle go it came back i don't know it was weird but Mazda dealers put a new motor in an its not doin it..does it sound anything like wat i just said?

Yes, that's describes pretty much exactly what I'm hearing.

If you take off the plastic intercooler cover you can hear it much louder than when the cover is on. When the cover is off you can put your finger on the pump and feel that the knocking sound and the vibration from the pump are happening at the exact same time.

Like mentioned as you rev up the engine the sound smooths out, but it comes back louder when the car is idling.

I wouldn't worry about it - that's my $0.02

Thanks for the info. I'll remove the cover and see if the pump is indeed where it is coming from.

 

[speede606]

What about when the AC is on?

Hello everyone!

I haven't been on these forums in a while so hello! I have been looking for an answer for this knocking (sounds almost like a clicking) sound that comes at idle. I know it is not the Variable Swirl control system shutter valve stuck closed because my symptoms do not match up exactly with what has been described on this page. What I am wondering is if this fuel pump issue is the problem. However, I notice several different symptoms in additional to what has already been discussed here and please forgive me if I am beating a dead horse and this has already been covered.

I notice a couple additional factors. 1- that knocking sound does not always happen on a consistent and regular basis (although it has become more regular recently) and 2- it tends to come on more when there is a load of some kind on the engine, i.e. when I turn my AC in the car on and roll down the window I can hear the knocking sound. Any suggestions or info on if this is the same problem? Thanks for the input!