[dr.abhijeet]

Originally Posted by SS-Traveller

@mercedised: The complete cylinder head has been replaced, including cams and valves. Even if a cam lobe was worn out, there's a new cam inside now. And this is an OHC engine, no pushrods there.

If cyl2 shows loss of compression after 500km, a leak test would of course be in order to check for integrity of the rings/cylinder wall.

sir one single complete cylinder cannot be replaced, only the head,
for changing the cylinders u need to change the engine.

@ tsk , sir i m not talking about a cracked cynlider head , but the body of the cylider

[dadu]

Originally Posted by tsk1979

Since the problem has reduced to a large extent, and fluctuation is very minimal, I guess this step will be done when the fluctuations increase. Leaks only get worse with time. So lets see, another 500kms to go!

Hopefully is they found "the" leak, it should have stopped, although heat helps in seating but then all new engines should show these symptoms out of factory. I sincerely hope this is the end to it.

Ok, we have gone from Air intake sensors to fuel injectors and rail changes but the Puzzle's:

• How did it go away by changing some washers in the injector seats ??, where was the leak then.
• When the engine warms up, the problem is not noticed, due to metal expansion or sensors start reading the expected data, miraculously.

btw, there's one more fuel temp sensor mounted near the fuel pump that manages the injection, changed ??

[tsk1979]

Fuel temp sensor was never changed, but I guess that also cannot cause compression loss.
Meanwhile I spoke to the customer care tech head, about how they go about diagnosing compression loss. He explained the following. I could not get some of it, but technically proficient among you will know.

They attach this pressure guage to the head. All cylinders normally show 24/25 pressure. The manual says 26+/-1 but due to leakages in guage etc., safaris report 24/25.
Now one cylinder was showing 20.
Therefore, they put oil on the rings(piston rings), and pressure in all cylindrers rose to 28 approx. But the cylinder showing 20 did not rise.
If the leak was from bottom half, that would also have risen.
Thats how they came to a conclusion that something was wrong in the head itself.
After head change, the problem has drastically reduced. I can't say its gone 100%, but more like 95% gone. I have seen little fluctuation in all safaris actually when the engine is cold. Infact most diesels have that rough idle chatter when started up cold.
Here is may be slightly more.
So its entirely possible that there is a very minor leak in the rings also.
So driving 500kms should make that issue show up.
Fingers crossed for now.
If problem persists, I will ask them to do another compression test, if compression is not 24/25 then I guess its engine replacement time.

Dadu sent me a link, I will quote from that. It pertains Audi

Wavering idle speed with cold/warm engine.
Cause:
A smaller vacuum hose branches off from the crankcase ventilation, which is routed as bypass around the throttle valve. Especially in winter the throttle hose and/or the vacuum hose can become clogged and/or iced up with crankcase condense water. Consequently the idle speed wavers by several 100 rpm during the phase of warming up, gradually dying down as the engine heats up. Pulsations in the air inlet hose are possible through the crankcase ventilation.
This leads mainly to wavering idle speed with switched on electrical consumers and air conditioning with a warm engine.
Models affected: ADP engine 1.6 l
Service:
Take away the intake hose complete with crankcase ventilation hose and vacuum hose. Clean the throttle hole, 2 mm (4) diameter, and hose of the vacuum (3). Take away the cylinder head cover, put in the new oil splash guard and get rid of the old one - Part No. 06A 103 544 - (unscrewed).
Adjust the cylinder head cover and intake hose. Do not lose the O ring and make sure it doesn't lose itself in the neck of the crankcase ventilation hose. A tiny wavering of idle speed by approx. 50 rpm when the vehicle is still rolling and the clutch is pressed down is no cause for concern and is normal.

Now I was getting the exact same thing. On warm engine fluctuation was there when electrical consumers were switched on. eg Air conditioning.
Hints and Tips : Audi idle speed problems

[dr.abhijeet]

Originally Posted by tsk1979

Fuel temp sensor was never changed, but I guess that also cannot cause compression loss.
Meanwhile I spoke to the customer care tech head, about how they go about diagnosing compression loss. He explained the following. I could not get some of it, but technically proficient among you will know.

They attach this pressure guage to the head. All cylinders normally show 24/25 pressure. The manual says 26+/-1 but due to leakages in guage etc., safaris report 24/25.
Now one cylinder was showing 20.
Therefore, they put oil on the rings(piston rings), and pressure in all cylindrers rose to 28 approx. But the cylinder showing 20 did not rise.
If the leak was from bottom half, that would also have risen.
Thats how they came to a conclusion that something was wrong in the head itself.
After head change, the problem has drastically reduced. I can't say its gone 100%, but more like 95% gone. I have seen little fluctuation in all safaris actually when the engine is cold. Infact most diesels have that rough idle chatter when started up cold.
Here is may be slightly more.
So its entirely possible that there is a very minor leak in the rings also.
So driving 500kms should make that issue show up.
Fingers crossed for now.
If problem persists, I will ask them to do another compression test, if compression is not 24/25 then I guess its engine replacement time.

this is how a standard compression testing is done, minuscule amount of leakage is possible from rings which gets sealed by oil, as seen in ur case

u see the only way to find out if the problem is gone is to do another compression testing.

u see i have only worked on old HM DIESELS so not much idea about sensors and stuff, to my limited knowledge of car electronics the rising and falling of rpms is due to the ecu sensing 1 of the cylinders not producing enough power so increasing rpm ro compensate for the loss.

but as we say dont go for symptomatic relief, see if the disease has been cured

^^^ hmm that link is interesting hmmm

[suman]

Hmmm, hope its the "final" fix this time!

PS: The white elephant is in good company Tanveer, nice to know that Audis exhibit similar "symptoms"

Bloody shoddy Audi quality!! (sorry, couldn't resist that one )

[Jaggu]

Cold starting diesels might sound loud but RPM should'nt bounce, atleast i havent seen that in any of the modern diesels or for that matter most of the well kept petrol ecm type engines.

Compression check they did is the right method. Though they should double check the same to see if the issue is resolved after the job.

[anujmishra]

Just my thought!!! Why don't you change your RPM meter and check this fluctuation comes or not? May that RPM meter is faulty and all parts getting replaced one by one.

I can see many speedometer fluctuates. I think speedo meter and RPM meter both work on same principle.

[4x4addict]

Originally Posted by anujmishra

Just my thought!!! Why don't you change your RPM meter and check this fluctuation comes or not? May that RPM meter is faulty and all parts getting replaced one by one.

I can see many speedometer fluctuates. I think speedo meter and RPM meter both work on same principle.

Anuj, I thought if this angle a while back but tsk has repsonded with a video where you can actually hear the engine noise rise and lower so it is not an issue with the meter. The engine is actually idling erratically.

[Jaggu]

So any further updates on this tsk? Are they agreeing for an engine replacement?

[tsk1979]

The problem still remains, but now I have doubts. What if the problem is related to some other component, or sensor. There are a million of those things in the 2.2!

[Rahulk76]

Originally Posted by tsk1979

The problem still remains, but now I have doubts. What if the problem is related to some other component, or sensor. There are a million of those things in the 2.2!

Tanveer.. with all due respect, Please ask for complete engine replacement. This hunting issue or whatever technical term has led to 3 -4 complete "Bare Engine Replacements" in Pune.

Please check you PM.

[MileCruncher]

Originally Posted by tsk1979

The problem still remains, but now I have doubts. What if the problem is related to some other component, or sensor. There are a million of those things in the 2.2!

Have you checked the alternator and seen if there is any problem with that or not.

If that also has been done, then I suggest you ask for whole engine replacement

[Rahulk76]

Originally Posted by dadu

Hopefully is they found "the" leak, it should have stopped, although heat helps in seating but then all new engines should show these symptoms out of factory. I sincerely hope this is the end to it.

Ok, we have gone from Air intake sensors to fuel injectors and rail changes but the Puzzle's:

• How did it go away by changing some washers in the injector seats ??, where was the leak then.
• When the engine warms up, the problem is not noticed, due to metal expansion or sensors start reading the expected data, miraculously.

btw, there's one more fuel temp sensor mounted near the fuel pump that manages the injection, changed ??

Dadu, apart from injectors from where minor leaks can happen, the other important source of leakage is the glowplugs. They can have minor leaks as well

[Jaggu]

Let me repeat again, please ask them or rather insist on ENGINE REPLACEMENT! There is no point in further experimentation if its a one off case and cannot be replicated on other vehicles.

[sbhaduri]

Tanveer thats what i mailed you sometime back.Insist on an Engine replacement if this thing cannot be replicated on other 2.2's.Let TML take your old engine and study and experiment on that.

I hope a proper TML R&D person is involved with the diagnosis in your engine.

Originally Posted by Jaggu

Let me repeat again, please ask them or rather insist on ENGINE REPLACEMENT! There is no point in further experimentation if its a one off case and cannot be replicated on other vehicles.