Weird Knocking

[Emode]

Tonight when I after i got home, as i was letting the engine idle, i got out and heard a slight knocking coming from the engine. Upon further inspection i realized that the knocking sounded like it was coming from the rear left of the engine, It is relatively faint, and rythmic to the running of the engine. I have not really noticed this before, but i dont think its normal. Has anyone else heard this? Another thing to note is that a few days ago i installed four of the iridium IX spark plugs from Sparcko online. The tips of the plugs are very fine, and one of them got a little worn down when we were spacing them, (.7-.8mm) Could this have some effect on firing? I have already decided i dont like them, because it actually seems as if i have lost some top end power, and have ordered the NGK heat level 7 copper plugs to replace them. I wouldent have installed the iridiums after the one got worn, but after taking the other ones out i couldnt reuse them. Any ideas? thanks
rob

 

[EVILSRT]

Damn it could be a rod man...if it gets worse you could a have a BIG problem......take it in ASAP!!!

 

[Emode]

**** thats exactly what i didnt want to hear

 

[flat_black]

Uhm, it may be the plugs, too... You aren't supposed to change the gap on Iridium plugs, I don't beleive. I would put in a set of copper NGK's to see if that helps.

 

[changedman]

arent most plugs these days pre gapped?

 

[ForceFed]

Most plugs these days are pre-gapped but not for each individual car.they are all gapped the same from the factory then you have to gap them to your car's specs.I used to work in auto parts and in service for many years so i know first hand.
Everyone has a misconception of plugs being pre-gapped and then they just buy them and take um home and put um in without checking the gap.This is a NO-NO!
Always check the gap on your plugs,even if you think they are pre-gapped from the factory as they do get shipped and bumped around and this could change the gap setting!
Also when you gap them it is sometimes recomended to gap them a thousandth or two smaller than spec as the heat from the combustion chamber will over time open the gap up bigger than you set it.
Matt

 

[flat_black]

Most copper plugs are pre gapped, yes, but they should be regapped before installation, regardless. But the iridium plugs are special cases, due to the fact that they will produce a more powerful (hotter) spark if the gap is too close, and colder if the gap is too large. The plugs are gapped as they are to provide the proper heat range, and spark length.

A friend with a Focus installed the Iridium plugs, gapping them first, and had drivability issues... He took them out, and compared them to another Iridium plug of the same part number, and checked the gap with a feeler gauge, then re-gapped it to the longer gap, and those issues were resolved without a problem.

Another thing to keep in mind, it's very easy to damage the iridium landing, as it deforms with the slightest pressure, from what I saw. Just a few thoughts!

- Eddie