AKE intermittent rough engine

[two left feet]

evening all, i have a 2002 a6 4b 2.5 AKE with 240,000 kms, in the last 4 months Edward (old iron) started running rough and had a real rough idle. started with injector cleaner / diesel additive, which helped - for a week, then it returned. another few treatments had the same outcome. then tried the 1:200 two stroke oil in the diesel. helped or a few days then, the rough running returned.
i m guessing this is a injector malfunction, rather than a nozzle issue. my next plan is to get the injectors cleaned and checked at Bosch. should i start to get worried about the vp44 or cams? any thoughts?
havent had The car checked for error codes as yet.

 

[two left feet]

5 months later...

injector number 3 replaced, timing chain replaced, injector clean and two stroke oil had no real benefit...

next step, injectors out andclean / refurb....

stay tuned..

options left, DMF, engine mounts....

 

[adamss24]

I will stop wasting money and check the cams in both heads...

 

[two left feet]

i had been considering cams, any idea on costs? ?

 

[two left feet]

wtf, found a surprise when i opened the left bank rocker cover.

opened the rocker cover this morning to remove the injectors, had a glimpse into the cam and valve area. noticed that a rocker arm had "disengaged" inself from the cam and valve on cylinder 1. the guide from the top of the valve stem had fallen off also.

so the engine was running with cylinder 1 with only 3 functioning valves.

question, how the hell can this happen, and the car still runs ok? and then how to fix?

i searched every where on the web and could see this problem....

 

[AlexGSi2000]

Are the cams worn?
Broken hydraulic lifters can cause the arm to fall out - mine did this.

 

[two left feet]

cams did not appear worn.

 

[two left feet]

what sort of fix is involved, assuming the lifter is defective? it
sounds costly..

 

[adamss24]

There might be issues with oil pressure, the hammer action from oil pump/stretched oil pump drive chain will dislodge the rocker arms off their guides... The engine has 4 valves per cylinder: 2 intake and 2 exhaust. When only one of each drops, the valves stay shut and the compression exits trough the remaining working valve. When 2 exhaust valves are shut the compression/exhaust gases will exit trough the intake and you will hear noise inside the airbox. The ECU compensates for wear by injecting a little more fuel into the next cylinder and as it happens gradually, you most likely would not notice any difference...till you drive a healthy one with bags more power !

 

[two left feet]

that explanation makes sense, thanks. so root cause may be in the oil pressure. is it a simple cases to slip the rocker arm in place, or does the cam have to be removed first? the cams themselves look in OK condition without any real sign of wear. best regards Andrew

 

[two left feet]

what did it cost to get the lifter replaced? .

 

[two left feet]

update....

treated all the injectors with ultrasonic (JPl) and rebuilt. rough idle is now gone. still missing a rocker arm on cylinder 1 inlet. now to get prices to get the rocker arm installed Z(and hydraulic lifter repaired)... thanks to Adamss24 for his advise..

 

[two left feet]

another update
rough idle soon returned (inside a week). terribly dissapointed that the ultrsonic cleaner work was for the bin.
Eventually went to local specialist who i asked to replace the rocker arm and lifter. call came in thisafternoon, cams are worn and should be replaced if i want to drive any longer. so have agreed and additionally asked that the engine mounts are replaced for new.
2k Euro later i will really be in the hole, but will simply enjow the ride..... wish me luck.. regards to all.

 

[two left feet]

last update.
replaced the clutch and dmf with Sach SRE and Sachs dmf. problem solved.
the dmf was quite worn and the engineer was quote sure this was the root cuase for the shaky idle.
but due to theage of the car, the fact that thére were multple issues was not that surprising.
now with that sorted, i now feel the need for more power.........
tis a slippery road

 

[quattrojames]

At least you fixed it :thumbsup: