Bit of a knock

[Parrot of Doom]

Theres a bit of a knock on either cylinder 1 or 2 of my engine (from the front that is). I can hear it faintly, its certainly not a massive knock, although I can feel it if I rest my finger on the line from the injector pump (its the bottom of the 2 lines).

The engine appears to run absolutely fine, I even filled the filter today with Redex injector cleaner to see what effect if any that would have. Doesn't appear to have made much of a difference tbh, although it can't have hurt anything.

You may just be able to hear the knock on this short mobile phone video but the sound quality isn't great. Use Quicktime to view.

Any suggestions? The clips for the injector lines to the cylinder head are all broken, I'm picking up new ones tomorrow, simple job to replace them all. If I push the knocking line with my finger, the tone of the 'knock' changes, gets louder/quieter.

Could it be as simple as the line vibrating because of the lack of the clip, or is it a poorly injector maybe?


/edit: youtube video:http://www.youtube.com/watch?v=-9FLGsp7rdQ

 

[Dieselman]

It could be the lines but unlikely, more likely is a squiffey injector or MAF or EGR valve letting in too much EGR.

Check the MAF output as if it is too low it will restrict the amount of fuel at idle causing an over lean mixture. Sounds odd but this can cause a real knock that can be much worse than yours is.
You can measure the MAF output using a digital meter. It should be about 2 volts at idle rising to 4.25v at full chat.

 

[Parrot of Doom]

Thanks Dieselman, I'll check that over.

I'm probably being paranoid The EGR valve spring is very strong still.

 

[GazCaff]

Where abouts in Manchester are you if you don't mind me asking?

 

[Parrot of Doom]

Urmston. Not far from you actually. I have a mate that lives in Leigh. I go cycling across Irlam Moss and down the Bridgewater canal

 

[mchips]

>>You can measure the MAF output using a digital meter. It should be about 2 volts at idle rising to 4.25v at full chat.<<

Can someone please explain how to hook up the connections to measure this? Where do you connect your multimeter probes? At least on my w202, I don't see anywhere you can make a connection to the MAF while the MAF is installed and the engine is running. Sorry to be so dense.

Thanks!

Doug

 

[Dieselman]

IIRC it's pin 5 on the MAF connector or back at the ECU.
Measure with respect to gnd.

 

[GazCaff]

Urmston. Not far from you actually. I have a mate that lives in Leigh. I go cycling across Irlam Moss and down the Bridgewater canal

Your welcome to have a listen to mine run if it helps at all, although a five pot won't be as smooth as a six pot.

 

[Parrot of Doom]

Thanks, I'm sure that theres nothing actually wrong with the engine, its probably just a bit mucky inside. I don't see anything breaking in the near future.