2003 Cayenne Turbo - Timing issues - Durametric diagnostics

[parabolic]

I've been having issues with rough idling and a slight 'knock' sound ( at full operating temp only )in my 9pa Cayenne Turbo.I've checked the cylinders (boroscoped) for damage and compression tested- and there is no cylinder scoring or leakage. Spark plugs have been replaced - and coils look fine (03 rev coils). No fault codes in engine module.I'm currently leaning towards a timing chain issue - whereas the knock sound is a result of a broken timing chain guide and/or stretched chain.Using durametric the cam deviation is reading a steady +1 ca / -1 ca. Actual cam timing is relatively synchronized between banks at all rpm.

Can anyone give me pointers as to what I should be logging with Durametric - so that I can post the log here for help in diagnosing this issue. ?

Edited June 30, 2013 by parabolic

[royxaxa]

I replaced timing chain and guide before because my bank 1 camshaft angle was off (deviation angle at -15CA and the other bank was +6CA I think, the limit is +-6CA)

one of the bigger guide was cracked and the old chain was about 1/4" longer than the new one, that however should not trigger any timing issue, tensioner should be able to compansate for that.

based on your deviation angel reading, i think your timing should be okay, cayenne V8 engines have tapping noise more or less, at least all turbos i've seen has that tapping noise

i would probably start from checking PCV valves(5 mins job, mine was broken), and clean the throttle body. replacing timing chain or adjusting timing is big job. I wrote something before regarding that and posted on 6speed. I did replace all guides, chains, tensioner, gaskets, O rings, starter, water pump, thermostat, cost me around $3k for parts. labor is around 25-30 hours, I did that with my mechanic buddy at his shop, so free labor LOL

good luck and let me know if you need more info

[parabolic]

Royxaxa - I read your description regarding the timing chain swap - and I was partially basing my assumptions on your writeup regarding the stretched chain and broken guides. I also spoke to the local Porsche workshop manager - who said the tapping noise was unusually heavy, and he agreed that the engine idle was indicating timing problems. This engine is now at 150k km - and I was leaning towards the chain as the culprit.

The strange thing is that the bad idle comes and goes - randomly. There are no preset conditions that trigger the bad idle - but the tapping noise ONLY appears with the engine at full operating temp. Maybe I need 5w-50 oil for this engine for the tappets at operating oil temp.?

I´ve recently changed the oil/filter (Motul 300v 5w-40) - waterpump/thermostat/cooling pipes - PCV is new and I´m about to change the diverter valves. There are no apparent vacuum leaks and the engine seems to run fine otherwise. What I haven´t ruled out is MAF´s - pre-cat Oxygen sensors - Coils. But there are no misfires or fuel mixture anomalies according to the durametric readout.

The only other issue is that the engine ´chokes/hesitates´ on quick throttle from idle.

[mcbit500]

Have you had any fuel pump problems yet?

[parabolic]

I haven´t checked the fuel pressure....if there was a problem with a fuel pump, wouldn´t it be apparent at higher rpm´s also ?

Edited July 2, 2013 by parabolic

[mcbit500]

Mine only affected me at low RPM until it wouldn't rev at all.

[royxaxa]

how about the readings from durametric? deviation and actual values. i think deviation should be constant regardless of rpm.

hows the interior of engine looks like? oil change intervals?

I would probably replace the tensioner first. it is around $70 and not too difficult to replace.(still pretty tight)

all that I am saying is that unless you are absolutely sure the timing chain is to blame, do not do it, it is a lot of work and could lead to more issues if not done properly.

are you going to let dealer to do it? or you have some reliable shop. it won't be cheap either way.

another thing, i always hear that 5W50 works better on higher mileage engines, i've never tried it myself. but i did switched from m1 to castrol and liqui moly. the engine burns less oil after the switch. and i am using liqui moly MoS2 now, it seems that it quiet down the engine a little.

[parabolic]

The Durametric readings look good. The cam deviation stays constant at -1 ca and +1 ca - throughout all rpm´s. Actual cam values are properly synchronized between banks at all rpm´s - 0 deg at idle up to 30 deg. So, there are no apparent problems there.

The interior of the engine looks VERY clean - the oil change service book shows an irregular but acceptable oil service interval. When i purchased the car I initially did an oil change with M1 0-w40 and again 5k km later - to Motul 300v 5-w40. My next change will be to Mobil-1 5-w50 (Rally formula). I´ve also used Liqui-Moly Ceratec and that did quiet the engine down considerably.

The thing is, I am far from being sure the rough idle and knock has anything to do with the chain - but in my mind it was the only diagnosis that fit both symptoms. Probably the best action would be to take the valve covers off and run a borescope down the chain housing. Maybe do the tensioner while at it.

Probably the knock and idle issues are unrelated - could be the poor thing just needs thicker oil and a new fuel pump :)

[Leela0826]

I too have a rough idle. I have a 2005 cayenne turbo. When I accelorate it seems as if the car builds itself up then takes off, but when the RPM passes 6 and enters into the red, the truck seems to jump or hesitate, almost like I'm slamming on the brakes then it takes off again. The engine light comes and goes and every time it throws p0016 which is camshaft and crankshaft position sensors. I had it checked out and was told there is no way to diagnose it as the timing belt without taking out the turbos out and blah blah blah. So, I am left to replace both sensors and go from there. What does this sound like? Help please!

I replaced timing chain and guide before because my bank 1 camshaft angle was off (deviation angle at -15CA and the other bank was +6CA I think, the limit is +-6CA)one of the bigger guide was cracked and the old chain was about 1/4" longer than the new one, that however should not trigger any timing issue, tensioner should be able to compansate for that.based on your deviation angel reading, i think your timing should be okay, cayenne V8 engines have tapping noise more or less, at least all turbos i've seen has that tapping noisei would probably start from checking PCV valves(5 mins job, mine was broken), and clean the throttle body. replacing timing chain or adjusting timing is big job. I wrote something before regarding that and posted on 6speed. I did replace all guides, chains, tensioner, gaskets, O rings, starter, water pump, thermostat, cost me around $3k for parts. labor is around 25-30 hours, I did that with my mechanic buddy at his shop, so free labor LOLgood luck and let me know if you need more info