Mister Bally

I'll add that skipping that step will result in improper belt tension that will result in early belt failure. Belt failure that can basically grenade the engine or at least ruin a dozen or more exhaust valves that are no fun to replace.

audi2l20v

Thank you Mishar and Mr. Bally!
Since I was a little afraid of DIY for timing belt, I have it done in local servise (not Audi one). The price was about 750$ with labor (in Bulgaria) so I prefered to have it done by proffesionals. They also changed thermostat and the camshaft seals, since right bank one was bleading a little (also all pulleys and tensioners, water pump, servise belt). It's a pitty I didn't tell them to change and the crankshaft seal. So after picking my car and first long trip around 1000 km I noticed engine power loss in high rpm. When the car is between 2000 and 3000 rpm everything looks ok, but it wouldn't spin over 4500 or 5000 rpm and seems to stumble. You have to release the throttle so the car upshifts and then you have more torgue and can accelerate only with lower rpm.
I have the shop double check the timing belt position and they do it with propper audi instruments - T40005 and 3242. So camshafts position is ok.
Now I have following issues wich could affect car performance:
- left bank hall sensor fault (for the past 2 years it didn' affectet performance so drasticly) and we checked the wiring - there is + and - and signal to computer.
- K&N air filter which probably affected MAF (for the past 80000km)
- ignition sparks changed before 18000 km
- ignition coils changed before 65000 km
- car is with LPG conversion (110000 km ago), so I'm sure power loss is not connected with fuel pumps - the car behaves the same with gas and with LPG
- the car have 320000km on it, so probably chain tensioners are bad and chains are stretched, but there is no rattling sound when you press the trottle
- intake air system is working - on low rpm vacuums are pulling the levers, over 4500 rpm vacuums release the levers and with engine shut, when you move one lever you can see the other one is moving a little bit, so I think the valves are moving inside the intake collector
- also when you floor the throttle there is CEL on gas, when you release it CEL goes off (on LPG CEL does't light)

So I replaced left and right bank hall sensors and will have the car checked for faults tomorrow - this will give me idea if the left bank hall sensor is bad or the copmuter wich reads the data. Also we will check for missfire (coils or sparks) and I hope this is the problem.

From the threads in the forum I understand that EGR valves could affect performance so vacuum lines have to be checked also some air lines under the air filter box.

If you have any sugestions and directions please share them!

I will post the error codes tomorrow.

Thanks again! Emil

mishar

So, lets talk tomorrow.

audi2l20v

Hi, after changing the hall sensor car behaves much better, it jumps up to 3500 rpm and revs to more of 5000 rpm, but still with some trembling. After scaning with VAS PC there were no engine fault codes, no misfire when runing on gasoline. But on LPG there is misfire on 6th and 8th cylinders. The guy running the scan didn't provide me with any log, so I can't share it. His suggestion is that the left bank catalityc converters are partially clogged. (could it be from prolonged driving with fault hall sensor?). Also he advises me to drive the car on gasoline for a week, so car could relearn itself to new ignition charts after beeing so long in emergency mode.
For sure I will change all sparks and if needed these two coils. Have to buy myself this VAS PC!

mishar

If your catalytic converter is clogged fix it first. Engine would act exactly like you described with it clogged.

03_AR_CO

Something like this?

mishar

Yes. Much better than Audi tool.

03_AR_CO

Mother is the necessity of invention, I found the crank pin hex plug stripped out, likely by previous timing belt job service people. So that hand fashioned bracket was the only thing I could think of to keep the crank stationary.

I know I asked why the cam sprockets needed to be loosened for the timing belt procedure, but once I was in there and saw with my eyes exactly how it all worked together, finally made sense. I did my first 4.2 timing belt procedure in December, and aside from the crank pin cover, all went well. Thank you for posting the how-to.

BostonSlaya

I am on my way to do this job very soon! I'm getting all OEM parts from
http://www.blauparts.com/audi_timing...placement.html.
This comes with everything even the coolant. I will be renting the whole tool kit to do the job from them as well as instructions. I have done many timing belt/chains in my life but this one scares me lol. Does the cams have to come out to replace the seals? Does the valve covers come off as well? I don't know much about this engine. Should I replace the cam chain as well? Any help would be appreciated. Thanks

MP4.2+6.0

Read sticky and do a search first. But to save some time for starters, see my reply #11 (the latest one as of this morning here) about timing belt work in this post: https://www.audiworld.com/forums/a8-...epair-2896683/ Your situation is similar, with same potential waste of time on seals, same unknown quality quality kit, etc. Actually, somewhat known...ask Mister Bally about his Blau Parts experiences broken down on the side of the road with his A8. Decide on how "new and improved" things are I guess. Why search is your friend too.

If you don't know much about the engine, you don't want to be fooling with the cam chains--have to pull valve covers, cams, tensioner assembly, keep intercam timing correct. No reason to absent issues, nor reason to do seals if not leaking as I pointed out in other post. I have pulled cams in a 4.2 (to do valve stem seals), so know what is involved. Again while these kits sound good and "cheap," they not just use non OES parts in a lot of cases, but also send people off doing work that creates more issues or problems--or lines owners' shelves with yet more "extras."

Relative to the other reply I linked, if you are at the 75K mile interval or thereabouts (you don't say), what I suggested there applies. If you are at the 150K interval, then I would do all the parts, but not with a kit with parts from unknown or non-tier 1/OES suppliers.