Question regarding injection quantity difference?

Hi and sorry for my english posting here!

Can anyone answer me how large difference in injection quantity between cylinders is tolerable? My Bosch KTS500 has a test where it mesures at idle the "menge differenze" (with injector number three as referens) i think the term was and I cant find what kind of numbers are right anywhere.

Once again, sorry for posting in english, my school-german cant help me with these tecnical questions.

Regards Fredrik

Max. +/- 2 mg/Hub or 2,5mg/Hub, sorry I do not remember. Anyway, everything above +/- 2 mg/Hub should be checked.
Please check also that the belt for alternator etc. is running smoothly. Keep in mind that the values in measurement block 13 are the injection quantity differences that the engine ECU gives to the injection pump in order to receive a constant angular rate of the crankshaft.

Best, Rainer

How the ECU get to these numbers were almost as interesting as the numbers itself. What is the prime reason that you can end up with to large difference between injectors? I get +2,3 mg/H and -1,0 mg/H on two cylinders. My A6 2.5 TDi AKE 180PS experience a jerkyness between 1200-2000 rpm when given throttle on higher gears and everything i checked so far seems right. Kind of stuck now...

Hi Frederik,

it can be any reason that lets a cylinder produce less power than the others. Even consuming more power at a specific position can show up this behaviour, e.g. a defect belt pulley.
The engine ECU knows the position of the crankshaft at any time, e.g. low compression on a cylinder lets the crankshaft rotate slower than with 'good' compression (with the same injection quantity).
Prime reasons for your AKN should be:
- bad injection nozzles
- defect camshafts. The camshafts tend to shake down. Hardened camshafts are available at your local dealer.

Best, Rainer

Is it a particular cylinder head that is more common with damaged camshafts? I have checked cylinder 1-3 with no damage to camshafts, car is a 2002 with 150000 Km on it.

Hi,

if the camshafts would be damaged, normally all of them should be affected...
Personally, I would continue with:
- checking compression
- checking injection nozzles

Best, Rainer

Hi,

The R4 TDIs have three liquid-filled mounts (Hydrolager).

But all V6 TDI have adjustable engine mounts. They are luquid-filled and have an on-off switchable air-chamber:
"open" for soft mounts, when idling
"closed" for a harder, torque-transferring mode when not ideling

Maybe your mounts are "always open" so the engine can shake hard.

This can explain the "jerkyness", but not really the "out of range" injection quantities.


martin

edit: I thougth "Lager" is mount in english, but leo.dict.org told me "support".
Now I replaced the occurences with "mount".

Thank you all for your answers!
I will continue checking compression this weekend. What is the most common reason if compression fails on these engines. Regarding injectors, they are non-rebuildable, right? So, only way to test these are with new one's or? Regarding engine-"lagers" I have kind of been suspicicios of those but then again, power-delivery is uneven, it's not only engine running "jerky" or unsmooth. I guess these engine mounts (lager) cant be the reason for that?

One more thing, have read a lot of EGR trouble, what's up with that?

the most wellknown cause for a lack of compression, is damaged camshafts. Look at all of them, when not all 4 are damaged, the injection quantity can try to smoothen the idle rpm (?). It also could be the piston-rings ore the valve-fitting, but not so likely. Failing power also could be becaused by the camshafts. I think, the engine mounts cannot cause this problem.

When you also have a problem with the EGR, close down this circuit (just to test it ), by a metal plate. That can also cause a loss of power (by loosing turbo pressure).

Normally you will see that the turbo-pressure is lower as specified, when the power is not available. That is my problem. It can be caused/amplified by these camshafts or EGR.

The injectors can be tested with a machine, normally every diesel-service has suchs a machine. Mine were tested for a few weeks.

The AKN motor also have a problem with the camshafts, mine are "badly" damaged at 170.000 km.

OT:
were are you from, what is your native language? My dutch is better, if it helps..

Sorry, i'm from Sweden, so dutch is definitely off the table

Regarding test of the injectors. My local diesel repair shop claims that there isn't possible to test step two of the injectors i.e the highest opening pressure. He can check the first step (235 bar opening pressure) only and of course check the looks and shape of the injected dieselcloud.

Is it true that there are in fact repair kits available for these injectors. They sure are possible to dismantle?

Regards

Hi,

Zitat:

Is it true that there are in fact repair kits available for these injectors. They sure are possible to dismantle?

I am working on this. Currently I only rebuild injection nozzles for the R4 VP TDIs.
There seem to exist more injection nozzles with problems for the V6 TDIs than for the R4, although much fewer V6 engines are on the road.

It needs special equipment to test the second opening stage of the nozzles, but in most cases, it is not necessary to test and adjust this.
If the 'spray image' is bad with the first stage, it will also be with the second.

Best, Rainer

klutten hat folgendes geschrieben:

He can check the first step (235 bar opening pressure) only and of course check the looks and shape of the injected dieselcloud.

True, he can also check if they close and do not lose pressure (dripping?). That is enough. If they are not OK, you will see it with this test, you do not need to test the second step. If the first is not out of range, you can be sure, the second is also OK, at least that is what they told me.

Be carefull with taken them out. The seals in the "Top of the Zylinderhead" cant be bought seperately...

I have changed my nozzles, changed to a new LMM and still misses the smooth power delivery between 1200-2000 rpm that i hope this engine should have. Checked the camshafts also, although they have very little rundown on some cylinders but it is barely visual and shouldnt affect the performance of the engine.

Im kind of stuck now but think of looking into the following:

catalysators, perhaps one of them are plugged?

The pump inside gas tank(Vorförderpumpe) does my A6 AKE has one?

Please, anyone with some ideas what to check next?

Regards Fredrik

Can it be checked in any way with the pump still in the car?