stutter and hesitation if fuel level above 1/4 tank!

[lewisweller]

Purge valve unplugged didn't have any effect. It threw a code p0444 as expected. 

 

[lewisweller]

With the tank nearly 3/4 full and assuming the left pump is running only as normal I can hear a gentle noise which sounds like air sucking through a pipe or maybe it's just the pump running infact. 

Can someone pls sit in their car at idle with AC off and tell me if they hear a quiet but definitely sound similar to this as normal?

 

I replaced both gasket rubbers and all connection are correct im sure when both pump replaced and filter and regulator before that.

 

Appreciated   

 

[ybe]

I can hear my pump sometimes but it more like a turbine or winning noise. Even though all connections are correct there have been stories of hoses coming loose in the tank from the pressure after driving

[lewisweller]

Crankshaft position sensor has arrived today will be installing it in the morning hoping for some positive improvements. 

New sensor Resistance measured 919ohms between pin 1&2 open circuit on other pin combinations. 

 

I will heat test the old sensor and see if its resistance increases when hot. 

[lewisweller]

Fitted new crankshaft position sensor was really easy you don't even need to remove any covers just put suspension in highest terrain position and switch off the regulation, then you can slide under and unscrew the 5mm Allen head bolt. 

 

Went for drive and it was fine, it even lasted longer than normal good running when already warm, but after doing some hard blasts it started again to stutter ......so disappointed. 

 

The only thing I learnt today is the idle Dip is only happening when the AC is on or slightly if I put a lot of loads on with AC off like rear defroster seat heaters and all lights and fogs. 

 

Is there any possibility the air gap of the sensor to the flywheel is the issue? Ie the very small gap is actually getting too small when the flywheel expands? 

Some engine have a spec for the air gap and sometimes this gap is adjusted to fix cps problems. 

Edited January 27, 2017 by lewisweller

[ekstroemtj]

Lewis. 

Of course no good news. Why you dont give it a try and change the camshaft solenoid?  You are very fast with taking away the valve cover. Parts will not be mich more than 120 Euro.

I believe its worth a try.

[ekstroemtj]

http://rennlist.com/forums/porsche-cayenne-forum/803207-camshaft-actuator-replacement.html

 

[lewisweller]

7 hours ago, ekstroemtj said:

http://rennlist.com/forums/porsche-cayenne-forum/803207-camshaft-actuator-replacement.html

 

I've been reading a lot about the variocam but what I read is not very helpful in terms of identifying my running issues to variocam faults. 

A lot of the info is other Porsche engines and not a lot specifically about the cayenne v8 engine. Does anyone have cayenne specific info pls? 

 

What I really struggle to understand and find info about is when the variocam exactly switches in to move the inlet camshaft (which is all it does on our engine I belive). 

 

Some other Porsche engines move the inlet cam at around 1500 rpm other over 2000rpm. 

 

From my understanding the system works like this and please someone correct me as I'm sure it won't be correct.......

1. Idle: the inlet cam is advanced 25 degrees to Give an overlap of exhaust and inlet valves for scavenging and better smoother idle and effiency in terms of fuel economy and NOX Gas reduction?

2. At 1500rpm the inlet cam retards  to original position until around 5500rpm giving a flatter wider torque curve? 

 

I'm sure that is wrong ..........but cant find proper info to understand better. 

 

 

Edited January 28, 2017 by lewisweller

[lewisweller]

I just disconnected both the camshaft actuator solenoids and nothing happened. I revved up to 1k then up over 2k exactly the same as usual vibration and bad running just over each. Then I revved full throttle a few time and it hold to the 4k rpm limit as normal and really I can't tell the difference with them disconnected. I didn't drive it though as I'm not sure if that's advisable really. 

Engine running throughout the following .........

I Measure the voltage 13.91v on one pin to earth and 2.95v on the other pin to earth (it's a negatively switched circuit so ignore that measurement I think) when I measured across them 11volts which is the two voltages deducted which make sense. 

When I plugged the connector back on bank 1 actuator I could hear tappy ticky rattle metalic valve train noise which tells me something happened. Bank 2 did not make the same noise. 

 

So what could this all mean? Bank 1 is working in a fashion and bank 2 isn't? It means nothing because they are not supposed to be active at idle? 

 

Loren please help.

[ekstroemtj]

I am not an expert but i believe the vario cam system is working at any idle.

 

 

[lewisweller]

4 hours ago, ekstroemtj said:

I am not an expert but i believe the vario cam system is working at any idle.

 

 

Thomas found that oil strainer you mentioned, its part number 20 and also is non returning as well, ie oil travels in but can't flow backwards out after it goes inside the actuator. So if the actuator was blocked, stuck or intermittent it would create some weird results. They added this part in 2005 when I guess they started seeing issues with the blocking up of actuators on early models and also they revised the actuator part up to revision 08. So they knew something was wrong with this design! 

Still not 100 % understanding the system and the attached video and all the ones I have watched relate to the "variocam plus" which uses high lift cam and valve locking pins. 

But the cayenne and panamera use only various cam (cam phasing) advance and retard of the inlet cam the valve lift height is fixed the inlet cam timing and thus cam overlap is adjustable only. 

So just to hypothesis as no one is coming up with any factual info just yet,

Let say it is either not working or blocked. I've read the system "fails on the low side" meaning it doesn't advance the inlet cam at low rpm as it should. This makes sense if the actuator doesn't work and the normal position is not advanced. 

 

So why don't I unplugged both actuators and see if it drives the same then bingo I must be on to something here. Or maybe it's just one side and the other bank is OK. So then I could unplug 1 side only and test and then switch. 

 

I also read the actuators can be brought back to life with some shock treatments! Some w12 and pheoton engines responded to this. I expect if the solenoid is working OK when cold it is not a oil blockage and more than likely the coil windings going high resistance and then the valve doesn't actuate fully or gets stuck. Maybe the cold start has the effect of compensating for this but once hot it can't. ?!??

 

Many questions just begging for a knowledgeable chap to chime in with some facts.....anyone?

 

some interesting info below relating to turbo engines........ 

"Retarding overall cam timing: Retarding overall cam timing is better for high-RPM power. This is because the valves are closing later. The intake valve is closing AFTER the piston has started to travel back up the bore for the start of compression stroke. This is terrible at low RPM because the intake air velocity is low, and air that was once in the cylinder is now being pushed back into the intake manifold and causing turbulence"
 

http://www.hamotorsports.com/cam-gear-tuning.html

Edited January 28, 2017 by lewisweller

[ekstroemtj]

I spend now some hours to search in some german porsche forums.  I would bet its the actuator and its filter.

 

[lewisweller]

6 hours ago, ekstroemtj said:

I spend now some hours to search in some german porsche forums.  I would bet its the actuator and its filter.

 

Looking at my pictures from when the indy did the head gaskets the whole head was stripped and the actuators removed so the chances that it is blocked are less. The car was stuttering immediately after they returned it to me and was like it before they did the head gaskets. So I believe it is most likely the actuator is getting warm and malfunctioning unless when the car is warming up the non advanced inlet cam doesn't have much effect on the engines running characteristics until it's warm / hot then the cool air coming in and bouncing back off the the rising piston is trying to go back out of the inlet valves and creating a shock wave in the manifold which is the "stutter" I can feel until the rpm rise enough that the air velocity and weight don't allow it to bounce back as much ????

 

I also read some horror stories that the aluminium bolts of the cam phase adjuster back off and grind into the head eventually snapping and causing a really big problem. I think this was the later cayenne and panamera though. 

 

A small mirror can be used to inspect the bolt through the oil filler cap, I'm going to do this today and also run with actuators disconnected it won't cause damage I now understand. 

[lewisweller]

Ok, well I did some tests and have a conclusion!

 

Engine cold not started since yesterday. 

 

1. Measures the resistance of each solenoid actuator both are exactly 10.7 ohms. 

 

2. Connected some wire to earth and battery + and activated the solenoid (Engine still off), I hear a quiet but definite click so they both seem to work. 

 

3. I reconnected the solenoid plugs and started the engine, starts fine, during the warm up period I disconnected the plugs on each solenoid and nothing happens. Engine idles same. 

 

4. I reconnected the plugs and put my ammeter clamp around the brown and red strip + wire to measure the amperage the solenoid is drawing. At idle the amps was 0.45A (bank 1) and 0.36A (bank 2) dropping to 0.28A (both banks same) when engine was fully warm, when revving the amps would peak to 0.81A showing the solenoid is being activated more as the revs increase. 

 

5. Went for drive with both disconnected, instantly I can tell there is no low rpm power or torque! Power doesn't come until up around 4000rpm. (Feels like a crappy vtec engine) The stutter is still there but much less pronounced as low rpm power delivery is less and less agrresive and not because it has fixed the problem I don't think. 

 

6. Reconnected the bank 2 solenoid and drove for a short distance still doesnt feel powerful at low rpm but a little better, it's trying to deliver power. 

 

7. Reconnected bank 1 solenoid and power is back to normal low rpm good and high rpm as normal good. Stutter is still present through the lower rpm pickup and acceleration especially when boost comes in.  

 

8. Disconnected the MAP sensor to drive without boost and stutter is less pronounced but still there. 

 

So what did I learn. ????

 

Variocam is working I'm pretty sure this is conclusive. 

The system from my new understanding works like this. 

1. The inlet cam is always in the retarded position. The cam solenoid actuators when activated make the inlet cam advance giving a bigger valve overlap which encourages more power especially at low rpm when air flow is slower (hence when I disconnected them at idle it doesn't make any difference and when revving the amperage increases proportionality ie the actuator is energised and opening the oil flow to the cam phaser).

2. The terms used "variocam fails on the low side" means it fails in the retarded normal position. The solenoid doesn't advance the inlet cam when rpm increased. "Low side" refers to low rpm maybe? 

3. The oil flowing through the actuator pushes the cam phaser and helical gear to move the inlet cam to the advanced cam angle position as rpm increases beyond something around 1500rpm roughly?  

 

All the above is based on some assumptions and not on actual facts ( except the measurement taken and results of tests) so pls correct me if anyone knows better. 

 

[lewisweller]

Something I'm making a big big assumption on is the "new" BERU coils are working properly. What's the chances these little defective God forsaken pieces of s**t are faulty even though they are (were 8 months and 10k) new????

 

I still have the old ones. Tomorrow I'm going to put black tape on any of the cracked ones and throw all of the old ones back in. 

Thinking I was being the ever mindful new cayenne owner, when I bought the car the coils and plugs was the first job I did but come to think of it the car actually ran better on the test drive before I bought the car (boost was down cos divertor valve was split) but it didnt stutter like a fffffff**king Jim Davison joke.

If these turn out to be faulty my mate at the porsche parts desk may not be a mate for long if they don't honour a warranty claim for defective parts. Lol but I'm serious 

FYI I have inspection the new coils at least 3 times for any cracks or signs of anything wrong with them. "Apparently" when hot the internal resistance can increase or the windings can shorten increasing current draw and causing misfires. There is a transistor inside as well which can fudge when hot. 

 

[ekstroemtj]

Why you had to take the car to your Indy for the head job that time?

[lewisweller]

4 minutes ago, ekstroemtj said:

Why you had to take the car to your Indy for the head job that time?

Overheating at idle cos Head gaskets blew on bank 1. Replaced head gaskets on both banks. 

[lewisweller]

I just removed the new coils and put in the old cracked ones. (4 out of 8 were cracked)

The verdict is it drives the same but with worse misfire stutter. 

I drove it around for a while nice and hot and did some light cruising and some heavy acceleration which produces the same kind of stumbles and even harsher stutter misfire when boost and load comes in. So it really feels like coils misfiring under loads and lean mixture conditions is the reason. 

 

I got back to the parking and plugged in the vcds to check for codes which I was sure there must be something for all the bucking it did but nothing. Unbelievable! Obd2 is w*nk. 

 

I'm going to take these new coils back to Porsche parts desk tomorrow and ask them to have them tested either on another known good vehicle or send them for technical testing. I will be pushing hard for warranty replacement but I know the first answer will be no. 

 

[ekstroemtj]

Dont even remember what you already did everything to find out where the problem is. 

- did you rule out some voltage problem which is related with the ignition? Possible to measure the power flow to every single coil?

[lewisweller]

Dealer where I bought the coils from want to have the car in for testing of the coil. I said that's fine but don't expect to be sending me a workshop bill. He said he would call me later to confirm. 

Calls later and says 800dhs to test the car in their workshop. I promptly reminded him the parts only cost 1500dhs so really I'm not happy with this Cock and Bull approach to a warranty claim. I said take the coils which I already have packed in a bag ready, and fit them in a known working cayenne turbo. If the fault is now present in the known working car then it's the coils. Of course they won't do that because they can't get my vehicle in there workshop and charge me. 

Anyway I'm going to see the manager tomorrow or Thursday and try to twist his arm. 

[wizard]

I admire your persistence. However, if memory serves, you've had warranty claims on 2 new batteries, and now coil packs, potentially.  

 

It may make finding the solution to your problems a lot easier by having Porsche identify where the problems originate and then take it from there yourself?

 

Just a thought.

Edited January 31, 2017 by wizard

[lewisweller]

2 hours ago, wizard said:

I admire your persistence. However, if memory serves, you've had warranty claims on 2 new batteries, and now coil packs, potentially.  

 

It may make finding the solution to your problems a lot easier by having Porsche identify where the problems originate and then take it from there yourself?

 

Just a thought.

Valid point and I don't doubt the porsche dealership has much better capabilities than most, although the car has been to two indy's, the first has genuine PIWIS (German owner) and I watched with great interest as they scanned and viewed all the systems looking for faults and particularly misfires there was none. The second indy (German manager) has duremetrics and they also did the head gaskets for me. Long story short neither could find one single problem with the car which is a bitch when its obviously not right. So couple that with my genuine vcds from Ross tech which despite its crossover issues from vagcom and shared Porsche vw modules does deliver codes and data to an extent just fine also has never popped a misfire code. I've unplugged stuff and made codes pop, I've has a split pipe to n75 and got overboost code, I've got a SAI code which comes if I have a rare cold cold start, (sai are pneumatically fudged so I get "insufficient flow").

Subsequent to these indy's work I found the following faults and fixed them but never fixed the misfire.

1. Split pipes from change over valve to DV's

2. DV drivers side split diaphragm 

3. Cracked coils 

4. Alternator died 

5. Battery dead (now on the 3rd under warranty defect and going strong)

6. Few other things I can't remember just now. 

 

So this is a unique issue in the fact it's not giving up itself in the conventional manner and I feel a day in Porsche workshop at 800 per hour will run me into 4000-5000dhs without any resolve. Without codes they are just as dumbfounded as me and any other garages. 

[ekstroemtj]

I unfortunately need to agree. Looks like some problems with this Vehikel are realy tricky and hard to find. I remember when i got my first Cayenne years ago the car started to have  random psm warnings. I cant even count how many hours this car spend in the service. Thousand for parts and labour. It worked only flueless for some days . the Problem came back..... Until now. End oft the story, even so called specialists can fail to find a Problem. But the money is gone.

[lewisweller]

34 minutes ago, ekstroemtj said:

I unfortunately need to agree. Looks like some problems with this Vehikel are realy tricky and hard to find. I remember when i got my first Cayenne years ago the car started to have  random psm warnings. I cant even count how many hours this car spend in the service. Thousand for parts and labour. It worked only flueless for some days . the Problem came back..... Until now. End oft the story, even so called specialists can fail to find a Problem. But the money is gone.

That says a lot from a German man, living in Germany with two German cars. 

If I could have any guarantee that they would be able to fix the problem I would really save up the money and do it to end my misery but I'm sure they won't find anything in the conventional manner and knowing the level of expertise here in uae they won't even go beyond my tech ability. And that's not being big headed it's just a fact of this part of the world and the level of experience and creative thinking here for anything "outside of the box". 

You watch you tube video's of Scannerdanner, now thats what a top automotive technician is! 

[wizard]

I may be way off the mark here, but have you considered a failing/blocked catalytic converter as the possible source of stuttering/misfiring?

 

Yes, after 40 years of car ownership in Bahrain, I know what you mean :-)

 

 

Edited February 1, 2017 by wizard