Misfires

[mbagge01]

On my 2004 cayenne turbo with EVOM tune, I have been having stuttering under high boost with CEL coming on and codes reading out as misfires on 3 of the 4 bank 2 cylinders. My first guess is spark plugs or coils. I run revision 09 coils and Oem spark plugs that I gapped to .030. I am assuming that coils or spark plugs are going bad but would it be unusually that it has only happened on one bank of the engine. My plan is to replace all coils and spark plugs with upgraded revision ones but should I be looking for something else since this focused to one bank. Also should I be fine keeping the plugs at the recommended .032 gap with a tune.

[JFP in PA]

I would suggest contacting the company that produced the tune for their toughts.  Most aftermarket tunes, and particularly on turbo models, need both a slightly colder plug and a tighter gap to elevate misfires and even burning the plug electrodes.

[mbagge01]

With all the coil revisions that porsche has been through, is there any evidence that the new revision coils .21 have a stronger spark or are more durable made?

[JFP in PA]

With all the coil revisions that porsche has been through, is there any evidence that the new revision coils .21 have a stronger spark or are more durable made?

 

Better made perhaps, no data on hotter spark.

[clarksongli]

Move the coils to the opposite side and see if the misfires follow the coilpacks.  If it does, then you know its the coils, if it doesn't then it's something else.

 

You can do the same with the plugs as well.  Mindlessly buying parts doesn't seem to be a good way to solve this issue.

 

Plug gap is fine, you're running the correct heat range plug, i know you said they are OEM, just make sure they are.

 

30 vs. 32 gap shouldnt make a difference.

[PKN]

I spent a long time chasing a similar problem for which my Durametric was of little help. It turned out to be the front O2 sensor which is a bear to change out but relatively inexpensive. If you have over 100,000 miles on the car, I would swap them out anyway

Steve

[mbagge01]

I ended up replacing all the coils to the newest ones and replaced to denso platinum spark plugs recommended by EVOM with stock OEM beru plugs and car runs perfectly now. I think it ultimately was the spark plugs

Edited January 4, 2016 by mbagge01

[mbagge01]

After further driving, it was not the spark plugs causing the problems as it kept coming back. Today I did some pressure testing and low an behold, I found that the T-fitting at the back of the engine for the crankcase was completely cracked apart and wide open. I did best I could of a fix to reconnect it back together and so far the car seems to be running better but I will give it more time before I can confirm that. I do have a question in regards to when this crankcase line is cracked open. Can it cause surging like issues during heavy acceleration. Idle seems fine and mild acceleration seems fine but going under WOT was giving me problems. Can a leak in the crankcase cause such a significant issues but not give me any CEL codes?

Edited June 20, 2016 by mbagge01

[lewisweller]

How did you perform the pressure test?.

I've had stutter and surging on my ctt at 2k 3k and 4k approx rpms but to red line it's perfect and despite finding a split vac pipe from the change over valve to the T piece near the Throttle body, which made a great improvement to boost the stutter is still there.

I would suggest you clean your Maf sensors and the MAP sensor. I've read this can also cause stutter and on boost related problems. When I get back from vacation I'm doing the MAP sensor, MAF cleaning done and no difference.

I don't have any fault codes or CEL ever.

If you switch off the PSM does this change it? If so you know it the tuning/DME issue that I've read used to be an issue which Porsche had an update for apparently, although Im leaning towards this being manufacturer speak for we can't really fix this characteristic.

I've posted a lot about my issues but your the first to have anything the same or similar. Most others are ignition or boost related issues with fault codes to mention.

Looking forward to your replies.

[lewisweller]

Mbagge01

FYI I replied to your post "shuddering boost" started in April.

Check your N75 soleniod which controls boost! When hot can malfunction apparently. I may have the same issue. I will be changing mine when I'm off vacation and cleaning my MAP sensor in the hope I can kill this bug once and for all.

[mbagge01]

lewisweller, I went ahead and bought the Porsche boost tester kit and when I pressurized the system, air was flowing out of this cracked pipe at the back of the engine. I have already replaced the N75 valve, map sensor and MAF sensors, coils and spark plugs along with diverter solenoid with no improvement so I am going to drive some more to see if fixing the crankcase vent  leak helps fix the problem. Everything I reset the ECU, even before the fix, the car would drive great for about 10 minutes until the studdering would occur which would make me wonder if the car starts adapting at some point to a leak.

[lewisweller]

Wow you thrown so cash at this pig. What about o2 sensor and temp sensor? I've heard some members changed the first o2 sensor after having running issues without fault code. But I don't advocate swapping parts in the hope to find the problem cause unless money is no issue and problem keeps you awake at night. Lol.

The cayenne has so many vac pipes it unbelievable and at these ages so many brittle plastic pipes make life he'll to find leaks without a leak tester.

What I found must profound was after I drive mine for 600km following head Gasket engine out top end rebuild was it ran better. When I first got it back from garage it was terrible still, I then found the vac pipe leaking and replaced the DV's. After it got better and better stutter wise. Then I disconnected the battery and I went back to running and stuttering like a chump.

Dme learning or adaption must be at play here but I don't understand why it runs like a turd for so long?

I also do belive the pcv side is leaking somewhere because when I pull the dip stick out whilst running it won't even bat am eye lid, rpm stable at 500 you would even know it was out.

So if you pull your dip stick out does the engine react?

Other member have said it does. So this leads me to think I have a small pcv leak and it compensated for it and possibly this is causing the stutter?

All complete guess work I know.

[mbagge01]

What is listed is not even the extent of parts I replaced and I am a little embarrassed to admit doing it because I know better than to just throw parts at it, but one thing led to another and I just headed down a rabbit hole thinking that I found the source of the problem each time. I believe in regards to pulling the dipstick is that if there is a leak, you should not see a difference in idling, and will if there it not.

[lewisweller]

I done some more searching and I notice also in your other post you are having running issues once warm but cold running Is better? So this would point at a closed loop related issue. The o2 sensor only comes into play once engine temp is up to a certain temp. If an o2 sensor is not responding it will most likely see a lean condition and fuel trims will be affected. If you have durametric you can check the sensors and fuel trims to see what data is shown. I sadly don't have durametric yet but on the wish list as will save a lot of money in garage bills and fault finding.

[ekstroemtj]

lewis.........

 

about the scanning tool try iCarsoft for Porsche. it helped me a lot with scanning and finding codes. Its not durametric of course but for basic things more than enough

[lewisweller]

Thanks Ekstroemtj.

I had a look at that but after review people said it was a good scan tool but couldn't reset oil, service reminders which is a pita.

I think the extra cash invested in durametric is a wise choice when I have the pennies saved up.

Anyone else got their opinion pls pipe in

[ekstroemtj]

Thanks Ekstroemtj. I had a look at that but after review people said it was a good scan tool but couldn't reset oil, service reminders which is a pita. I think the extra cash invested in durametric is a wise choice when I have the pennies saved up. Anyone else got their opinion pls pipe in

 

 

i agree !!!

[mbagge01]

Lewisweller, in regards to the O2 sensors, I have replaced all 4, but what was interesting is that when I logged with durametric, if was telling me that I have demonstrating very long injector opening times. I had the fuel system checked for appropriate pressure and the fuel pumps and filter have been replaced. Would some kind of a vacuum or boost leak cause injector timing issues. As you had mentioned, there is definitely something related to it occurring more once the vehicle has warmed up.

[lewisweller]

Given that the o2 sensors and fuel system has been checked I would be looking at vacuum leak, fuel injector sticking or blockage, and possibly temperature sensor. What are your fuel trims looking like? When your at idle and rev to 1500 and 2500 rpm you should see rapid changes in short term fuel trims.

Another consideration is low compression on one or more cylinders and a burnt non properly sealing exhaust valve.

When they did my head Gasket the exhaust valves were pretty well burnt and they grinder them and cleaned up well. My compression test pre head Gasket proved they were not leaking so I didn't replace the valves at 120$ each omg.

So have you done a compression test and leak down check? This is first for me.

Then if your confident your leak test was thorough then try some moly lube injector cleaner in the tank to maybe release a suspected injector sticky.

With out my detailed data from the o2 sensor and fuel trims on load and off load it's very hard to work this out.

[lewisweller]

Are you able to log and screen shot the data for each injector with the scale set so we can see the pulse width and closing spike voltage. This will help me see if the injector is problem or your running lean due to vacuum leak and the dme is purposely opening longer the injector to richer the mixture.

If your up for it, you can check the injector with an ohm meter, each one should have similar resistance. If your log the data we can see any problem without measuring the ohms of each injector though.

Another thought is you changed the o2 sensors but did you check the wiring harnesses? What does the data for the o2 sensors look like?

[PaulH]

I have been chasing a similar problem on my 2006 Turbo s 93,000 mls and i have just had to have my timing chain replaced as it had stretched its a tough pill to swallow but now feels like a new car !

[lewisweller]

I think I have just cured the lean running misfire stutter and hesitation at varying low rims. Today I smoke tested the intake assembly by blocking off the intake pipes before the maf sensor and putting my hillbilly inspired plastic bottle and cigarette with compressed air injection placed into the MAP sensor hole. Worked a treat but didn't show any leaks.

Whilst I was there I thought to check the vacuum pipes again which I fixed before for the Divertor valves, I was suppressed to find the right side DV was leaking through the vac hose. I removed it and replaced with ne 710 P revision. (the left is I already new and doesn't leak).

So put it all back together and just the short drive home I could feel the car adapting the stutter misfire and smoothing the power out as you would expect it too normally.

Some more driving should learn the dme the right mixture and long fuel trims and hopefully end of the nightmare I been chasing for months.

[ekstroemtj]

Genius !!!

[lewisweller]

Can't believe it, after two days of perfection the problem is back. I test the vacuum pipe and DV's for leak and none found. There must be something leaking somewhere again I need to find. I really thought I had this cracked once and for all.

What this space, I won't be beaten.!

[lewisweller]

Well guys and gals im still at it. Last few days the car ran as normal stutter, today this morning it ran very smooth, typical! I already made a plan and went ahead today to pull the plugs and coils (both new 2k ago OEM Beru coils revision 21 and Beru 14F-6DRUP021 OEM from Porsche) to check for coil cracks and correct plug gapping using 0.8mm as specified, all in the hope to find something or read the plugs to shine a light on the stutter surge hesitation issues.

see attached the plugs 2-8 (forgot to snap plug 1 but was exactly like plug 2)

To me the plugs look good, black full turn around top thread is good A/F mix, the centre electrode is white/grey as normal, only thing I would say is the ground strap is not showing very obvious signs of timing either advanced or retarded. it look very uniform colour on most and the faintess change on a couple. some website say no colour sign on the strap means plug is too cold, being in the middle east im very reluctant to put a hotter plug in!

Plug 3 had a small browning around the ceramic insulator above the nut more than others did but again not a real issue.

Any spark plug reading experts please do jump in and give your 2 pennies worth. :)

Also note one Picture of the connector of the Actuator Solenoid oring leaking a bit, anyone think this is real issue? Im thinking no, it doesn't drip or run, no fault codes at all!!!