2002 Mercedes E270 CDI W211 Loud idle (knocking) after 4-5 when cold

[enes]

Following my previous issue with seals and non-start due to injectors. I recon'ed 3 of them and no black smoke appears under load.

However, there is a knocking noise at low engine speed/idling when say manovering around a car park. This is more prevalent when starting from cold, it starts fine and then after about 4/5 seconds, the car doesnt idle properly (gets louder and rpm sounds like it falls slightly) and you can hear a knocking noise coming from the engine gets slightly louder as you rev the engine. It tends to fade away as the engine gets to 80c or when driven under load for a few minutes.

Any ideas?

Does it sounds like an injector issue?

180k on the clock

 

[V6Matty]

does sound injector related a little but with it happening from cold and while idle or light load, I'd also suspect the EGR may be clogged. could be worth taking it off and giving it a good clean and then doing the bypass mod created by Alex Crow, it works well and may save you other issues in the future.

 

[Pookis Dad]

Definitely an injector issue.

Three are pulsing as they should, nice spray pattern and good power delivery, the other three, will be down on power. Perhaps not significantly so, but compared with the new ones.......

I had the same issue with my lowly FIAT Doblo 1.9 jtd. You would swear the engine was going to shake itself out of the bay

Starting was difficult some days and power was way down, but I never noticed how much until I had the injectors done.

WOW!

It was like a rat up a pipe after that, so fast I was burning Audi's at the lights (or that could be something to do with the 177bhp the re-map gave it :twisted.

Starting was on the button without glowing (during the summer anyway) and the exhaust smell was non existent, whereas before it tended to be grey/white with black upon hard acceleration.

Of course it's currently off the road as I may have *ahem* stripped the teeth out of the box while burning a laddo in a turbo box (can't recall, Vx or VW). I beat him good, but then the noise and "ticking" gear stick prompted me to limp home

But I digress.....

Anyway, I would not waste time doing half the injectors to be honest. Get the others done asap.

 

[enes]

Just to note this issue was prevalent before I had changed my injectors the only difference was the black smoke generally.

 

[star]

Have you checked your glows are working correctly.

 

[Pookis Dad]

It just sounds like a misfire or timing is out...

Did you have all the injectors tested?

 

[enes]

all injectors not tested, leak back test revealed 2 were malfunctioning but I replaced 3 that had the highest leak back.

glow plug lights up and goes out after 1-2 seconds and the cars start almost immediately. Is there any other way to check them? Diag did not reveal such an issue