going mad cayenne s misfire and chugging cyl 2,5,7

[DavidSavopoulos]

Hi Guys,

 

New here, and found this posting similar to the problem that cropped up on my 2005 Cayenne TT today. Very rough through all RPMs. I almost thought the Cardem bearing had busted again because of the roughness. OBD2 says Cylinder 7 misfire. I have had recent engine light issues with fuel system that only comes on when it sits idling too long, or if I left the engine running while refilling the gas. Bought a new fuel cap and helped just a bit, but still get fuel system error occasionally. 

 

Could this be related, even if only number 7 is misfiring? Perhaps 7 is at the end of the fuel journey and gets lower pressure when either  the regulator or fuel pump go south?

 

i hate to think of the expense to guess my way through this, and am hoping someone out there gets a twinge of deja vu!

 

Any ideas?

[lewisweller]

3 hours ago, DavidSavopoulos said:

Hi Guys,

 

New here, and found this posting similar to the problem that cropped up on my 2005 Cayenne TT today. Very rough through all RPMs. I almost thought the Cardem bearing had busted again because of the roughness. OBD2 says Cylinder 7 misfire. I have had recent engine light issues with fuel system that only comes on when it sits idling too long, or if I left the engine running while refilling the gas. Bought a new fuel cap and helped just a bit, but still get fuel system error occasionally. 

 

Could this be related, even if only number 7 is misfiring? Perhaps 7 is at the end of the fuel journey and gets lower pressure when either  the regulator or fuel pump go south?

 

i hate to think of the expense to guess my way through this, and am hoping someone out there gets a twinge of deja vu!

 

Any ideas?

Unlikely fuel will create a single cylinder misfire so first thing is to switch ignition coil from 7 with 6 and see if the fault moves? If not put it back and move the spark plug instead. Rough running at all rpm is more likely ignition related. 

The fuel tank purge valve is renowned for causing problems with start up after refuelling but usually comes with a 0441 code, also possible is evap canister clogged saturated or something. 

Purge valve is in red on attached diagram. Pelican Parts has a good DIY. I changed mine already, pretty straight forward job, but I had the code to confirm the problem. 

[DavidSavopoulos]

Thanks very much for the great tips! I'll go over everything in the morning and see what I can figure out. Cheers!

David

[RFM]

You may never let the engine running while refueling, fuel system operates under a specific pressure by environement regulations, controled by the DME. This fact alone is already a reason for a MIL.

[DavidSavopoulos]

I should have been a bit more specific about the fueling. I had no choice during a recent 500-mile return trip but to fuel with the vehicle running due to battery issues. I understand the risks, but had no choice at the time. 

[lewisweller]

Despite the dangers of fuelling with the engine on and disrupting the fuel tanks operating pressure, here in the middle east lazy culture and the extreme heat, no one turns off their engine when refuelling or even gets out of their cars. I personally haven't had a code or related fault from refuelling with the engine on not to say its not possible. Maybe different country emissions regulations can make a code pop if refuelling whilst running but it would be the first I heard. 

[boscology@gmail.com]

I had similar issues after replacing plugs and coils finally got to the camshaft position sensors, 1 time i got a phantom code for them so i investigated. I did the same optimistic thing and cleaned my camshaft position sensors then it ran even slightly worse (I am not sure about if this helps now that I know how hall sensors work) replaced it and it is fine now

 

btw mine is also an 05

[lewisweller]

2 hours ago, boscology@gmail.com said:

I had similar issues after replacing plugs and coils finally got to the camshaft position sensors, 1 time i got a phantom code for them so i investigated. I did the same optimistic thing and cleaned my camshaft position sensors then it ran even slightly worse (I am not sure about if this helps now that I know how hall sensors work) replaced it and it is fine now

 

btw mine is also an 05

Interested to know what your running problem symptoms were? I got no codes ever to follow but still have a temperamental running issue of hesitation and stutter, startup, idle etc is perfect and wot is pretty good also up at high rpm but through 1k-4k its jittery kangaroo most of the time and even like it in neutral or park just revving you can feel at certain rpm's it's not happy. 

[boscology@gmail.com]

inconsistent rough idle and a feeling of lacking power or missing. The way those hall sensors work is interesting, when it ran the worst it would start fun and run fine til over 1k rpm or something then when I eventually decelerated it would be very rough because I assumed the cps wasnt sending updated rpm speed info to the engine

 

[lewisweller]

2 hours ago, boscology@gmail.com said:

inconsistent rough idle and a feeling of lacking power or missing. The way those hall sensors work is interesting, when it ran the worst it would start fun and run fine til over 1k rpm or something then when I eventually decelerated it would be very rough because I assumed the cps wasnt sending updated rpm speed info to the engine

 

Only a scope pickup to test the cps inductive pulse wave form will confirm if the sensor is the fault or if the timing is the issue ie stretched chain broken tensioner guides etc. 

If the garage fee is high then maybe cheaper to take a gamble and swap them both for peace of mind?

 

[D8TA]

Here's the original post.  

 

 

[D8TA]

I have a 2011 Cayenne and misfire reoccur after replacing the coil and the spark plug.   The mechanic determined it was a turned bad Fuel injector but the problem has returned!

 

[JKR]

I am having the same issue with my Porsche here in Canada with misfire code to cylinder 5 and 6.

compression good in 5 but 6 is 50psi

webt through all the steps.  Seems like this issue is too common and she be a recall?  I called but there isn’t one as told by Porsche rep over phone at 1800 Porsche.  

Optimus1 did you ever resolve the issue?

[JFP in PA]

8 minutes ago, JKR said:

I am having the same issue with my Porsche here in Canada with misfire code to cylinder 5 and 6.

compression good in 5 but 6 is 50psi

webt through all the steps.  Seems like this issue is too common and she be a recall?  I called but there isn’t one as told by Porsche rep over phone at 1800 Porsche.  

Optimus1 did you ever resolve the issue?

 

Welcome to RennTech

Borescope the bad cylinder looking for wall scuffing.

[JKR]

Ya scored cylinder 6

[DavidSavopoulos]

On 10/11/2016 at 12:50 PM, lewisweller said:

Interested to know what your running problem symptoms were? I got no codes ever to follow but still have a temperamental running issue of hesitation and stutter, startup, idle etc is perfect and wot is pretty good also up at high rpm but through 1k-4k its jittery kangaroo most of the time and even like it in neutral or park just revving you can feel at certain rpm's it's not happy. 

Sorry for the 2 year delay getting back to you! My issues turned out to be multiple, but the main culprit was a combination of issues in the fuel tank and fuel pumps. They had to remove the fuel tank and clean out tons of crap and contaminants, including rust, from it. Once they did that and replaced the fuel pumps, the Cayenne behaved like a new vehicle!