Go Back  AudiWorld Forums > Audi Models > Audi Q3 /Q5 / Q7 / Q8 > Audi Q7 > Q7 Discussion
Reload this Page >

Misfire Cylinder 2 - Please Help

Q7 Discussion Discussion forum for the Audi Q7 SUV built from 2005 to 2015
Sponsored By:
Sponsored By:

Misfire Cylinder 2 - Please Help

 
Old 05-05-2019, 03:19 PM
  #21  
AudiWorld Member
 
Join Date: Dec 2015
Location: 2007 Q7 3.6
Posts: 310
Default

my guess is its related to the oil leak. just a guess. I am guessing maybe the leak is at the intake. cuz that would cause a misfire.
I just noticed the post about power washing the engine.
I would warn you to not do that. power washing an engine risks messing up a lot of sensor, you just dont do it.
the proper way to clean oil to find the trail is with brake cleaner do not use chlorinated. and beware where it leaks down on the pavement that will stay there for a few months so put cardboard down or old blankets something that covers a lot of area.
several cans of brake clean will clean the oil and dirt right off, and try not to spray stickers as it will clean the ink off them lol.
carb cleaner will work too but I think brake cleaner is cheaper again dont use chlorinated it will eat rubber.
also, if the oil leak is at a seal you can put 1 bottle of AT-205 ATP Re-Seal Leak Stopper in there and it should stop the leak.
bspurloc is offline  
Old 05-05-2019, 07:20 PM
  #22  
AudiWorld Member
 
Join Date: Sep 2017
Location: Australia
Posts: 158
Default

Hi mate, there is a pretty good chance that the fuel injector for number 2 is on its way out. The symptoms that you described and the fact you already replaced the coil and spark plug doesn’t leave much left. The 4.2 is very probe to having “valley” leaks under the intake manifold. When the valley fills up with engine oil in has a drain passage drilled into the underside of the intake that will leak out just to the right of the intake actuators when looking at the fron of the engine. This will then flow down the front past the pulley etc and make a hell of a mess.

Upside is to repairing the underside oil leaks, is you will also have access to the number 2 injector and replace it if need be. If your not confident in tackling the engine work then by far take it to someone that knows their way around these engines and who wont rip the cash out of your wallet also.
Up-it is offline  
Old 05-05-2019, 08:36 PM
  #23  
AudiWorld Member
Thread Starter
 
Willgatlin25's Avatar
 
Join Date: Apr 2019
Posts: 80
Default

Well after driving from Enumclaw, WA to Ocean Shores, WA, all around and back.... Ended up driving about 500 miles. I didn’t have any issues until I took a trip back from the ocean to pick someone up and as I accelerated from a stop I got a misfire and the check engine light stuck on again.
If I drive the car really hard to extremely gentle it doesn’t misfire, but again if I drive it normally I get a misfire and I can feel the engine vibration like something is definitely a miss.
I may be exaggerating but I feel like the oil leak I have is significant. When I park and leave it overnight I come back to a ton of oil spots when I pull out of the parked spot.
I think my only option here is to consult a local mechanic that specializes in these vehicles, not the dealer, and see what they have to say. I know the injectors themselves aren’t that expensive but the labor to have the intake manifold taken off and put back on is what I’m worried about.

Here’s some pictures of the oil spots on the ground that I’m referring to.



Willgatlin25 is offline  
Old 05-05-2019, 09:52 PM
  #24  
AudiWorld Member
 
Join Date: Sep 2017
Location: Australia
Posts: 158
Default

Wow thats a little bit more oil spilled then my 4.2 but hey as long as you can get someone to track the point of the leak then they may have a chance of slowing it down. I have ordered a heap of seal for my 4.2 for this weekend as the oil cooler orings have failed aswell as re-seal the sump. Pretty much I have gotten on top of everything else but hey that 4.2 v8 noise is what is keeping me from letting it go.
the reason your fuel injector is more prone to missing during steady operation has more to do with the fuel mapping at thoses particular speeds. When you hit the gas pedal or just slightly the engine ecm make assumptions on more engine sensors at the time and thus makes your injector dump heaps of fuel or minor amount of fuel based on pedal commands then when driving steady it goes into a more pre-determined closed loop.
all in all the intake off and back on with the standard 4.2 oil filter pipes seals etc to be replaced shouldn’t take a good shop anywhere near 10hours to do mate. Take that a ball park idea for when shopping around.
Up-it is offline  
Old 05-06-2019, 08:31 PM
  #25  
AudiWorld Member
Thread Starter
 
Willgatlin25's Avatar
 
Join Date: Apr 2019
Posts: 80
Default

also, if the oil leak is at a seal you can put 1 bottle of AT-205 ATP Re-Seal Leak Stopper in there and it should stop the leak.
I used used a bunch of that standard engine degreaser spray that you can get at any Autozone. I removed the plastic trim covers from the top of the engine before spraying that stuff in the engine bay. I did notice a considerable amount of oil and grime down near the intake manifold on either side near the valve covers. Also quite a lot of oil and build up near the rear of the engine bay close to the throttle body area. I sprayed about 2 cans of that degreaser all over inside the engine bay, let soak for about 20 minutes, and then rinsed down the entire engine bay. I can tell you that some really nasty **** came out of there as I was watching the water run out of the engine bay and it was dark brown and a nice oil rainbow sheen...
It did leave one hell of a stain in my driveway which I considered would likely happen, but with a little brake cleaner the oil will come off the concrete... not my first rodeo getting oil on my driveway.
The water that comes off my driveway filters into a grass area instead of flowing into the storm drains and the run off completely killed my grass, so it was definitely nasty.

So the downside to washing the engine bay- No sensors were affected, and nothing was damaged. However, having said that, the seals around the coil packs are NOT water tight, not even remotely. So, after all my cleaning efforts I started the engine and it sounded like I just rallied it down a gravel road for about ten hours. The engine was shaking like crazy, check engine light flashing like mad.... I practically loaded my shorts thinking that I just ruined my car. But, after a bit of digging around I relaxed that I managed to fill up all the spark plug tubes with water so every single cylinder was misfiring.
Simple fix was to pull the coil packs and blow out everything with compressed air, dry the coil packs, touch of dielectric grease, and start her back up. After getting all the water out of there it ran fine.

But again this all preceded my trip to the ocean in which cylinder 2 misfired again and so I’m back to square one, however with a squeaky clean engine.

Right now my car is at a detail shop getting fully cleaned inside and out and then my next step will be coming up this Thursday where I’m having a diagnostic done at a local mechanic that specializes in German vehicles. Also considering I cleaned all the gunk and grime off the engine the mechanic will be able to trace back the new fresh oil leak trail or do a dye leak test if needed and not have to deal with all the nasty grime in the way of trying to pinpoint the leak(s).

I did want to ask about this AT-205 ATP Re-Seal Leak Stopper. Is this really a good product to put in my engine? I already tried some engine oil stop leak made by Prestone and it seems to have done absolutely nothing thus far. I found this ATP Re-Seal on Amazon for about 10 bucks USD.

Opinions?



Willgatlin25 is offline  
Old 05-09-2019, 04:43 PM
  #26  
AudiWorld Member
Thread Starter
 
Willgatlin25's Avatar
 
Join Date: Apr 2019
Posts: 80
Default DIAGNOSIS UPDATE

Just got back from Mouse Meat in Tacoma, WA- A local German auto specialist.

Oil leak diagnosis: Crankshaft Oil Seal has failed. Replacement seal $45 USD + Tax, Labor 2Hrs.

Misfire Cylinder 2: Possibly bad injector or carboned up valves. Replacement of Bosch injector is $158 USD + tax. Labor 6Hrs. Included in the labor time is evaluating how much carbon is built up and if cleaning is required.

Dropping off my Q7 this upcoming Monday and will report back once repairs are complete if misfire has stopped.
Willgatlin25 is offline  
Old 05-12-2019, 10:52 PM
  #27  
AudiWorld Member
Thread Starter
 
Willgatlin25's Avatar
 
Join Date: Apr 2019
Posts: 80
Default SPARK PLUG UPDATE

Another item to mention:
When the misfire first started happening I replaced the plugs. Admittedly I replaced the plugs with cheap single electrode autolite’s... Yes, I know that will contribute to further issues. Having said that the misfire still occurred in the same manner on cylinder 2.

Moving on to my point:
I started hand cleaning the factory plugs that I removed. All of them were pretty carboned up but no significant damage or signs of major combustion issues. So now that I’m literally on day 2 of gently hand cleaning I have all 8 of my factory plugs cleaned up beautifully. The plugs are either original OR someone had these plugs replaced by the dealership because they still have the VW/AUDI code stamped on them, not the NGK part number as if you’d ordered them directly from NGK.
Code on each plug is NGK VW AG 101905621B R1 JAPAN.

After cleaning I could clearly see that the center electrode points look to be in good condition. As well the 3 outer electrode prongs also appear to be in good condition with minimal wear. Factory spec says gap should be .036” and these gapped out after cleaning at .036”-.037”.

Also did a resistance test test on each plug and the results are as follows:
Plug 1- Resistance 1,230 Ohms
Plug 2- Resistance 1,260 Ohms
Plug 3- Resistance 1,280 Ohms
Plug 4- Resistance 1,300 Ohms
Plug 5- Resistance 1,340 Ohms
Plug 6- Resistance 1,360 Ohms
Plug 7- Resistance 1,360 Ohms
Plug 8- Resistance 1,390 Ohms

NGK’s Data-sheet States that these plugs come from the factory with a resistance of 1,000 Ohms plus or minus 5% variance.

Heres some before and after shots of the plugs:


Before Cleaning Close Up of Electrodes

After Cleaning Close Up of Electrodes

All 8 Plugs After Cleaning. Resistance Test Results Written on Each Plug

Looking for comments or opinions on the cleaning of these plugs. Thanks
Willgatlin25 is offline  
Old 05-14-2019, 07:50 PM
  #28  
AudiWorld Member
Thread Starter
 
Willgatlin25's Avatar
 
Join Date: Apr 2019
Posts: 80
Default REPAIR UPDATE 05/14/19

Mechanic has diagnosed the oil leak, after further digging into the issue, as several seals. Camshaft Oil Seal, Valley Pan Gasket, and All Upper / Lower Intake Seals. Oil pan gasket does not appear to be leaking.

Misfire was further diagnosed as being massive carbon build up, not a bad injector. Upper intake manifold is being cleaned as well as both lower. Below is a photo showing the lower intake manifold, left side, and you can see how the carbon build up has almost completely clogged the intake port over cylinder 2.


Lower Intake, Left Engine Side, Above Cylinder 2, BEFORE CLEANING

Lower Intake, Left Engine Side, Above Cylinder 2, AFTER CLEANING.

Carbon build up issue with direct injection on these FSI engines.... Nothing to stop it or prevent it. Unfortunately this is what happens.

Currently waiting for the motor to be reassembled and tested. Hopefully the errors are corrected after this work.
Willgatlin25 is offline  
Old 05-14-2019, 07:55 PM
  #29  
AudiWorld Senior Member
 
dreadlocks's Avatar
 
Join Date: Mar 2017
Location: Denver, CO
Posts: 1,277
Default

you can dramatically reduce buildup by driving it til it reaches operating temp every time, if you use it to go to work 4m away that EGR runs at 100% duty cycle.

Previous Owner probably rarely took it very far, you can delete the EGR and pretty much fix this issue.. newer direct injections have an extra injector on the intake thats operating when EGR is just to keep valve-train clean.

Last edited by dreadlocks; 05-14-2019 at 07:57 PM.
dreadlocks is offline  
Old 05-14-2019, 08:15 PM
  #30  
AudiWorld Member
Thread Starter
 
Willgatlin25's Avatar
 
Join Date: Apr 2019
Posts: 80
Default

Originally Posted by dreadlocks View Post
you can dramatically reduce buildup by driving it til it reaches operating temp every time, if you use it to go to work 4m away that EGR runs at 100% duty cycle.

Previous Owner probably rarely took it very far, you can delete the EGR and pretty much fix this issue.. newer direct injections have an extra injector on the intake thats operating when EGR is just to keep valve-train clean.
I’ll have to run the EGR Delete past my mechanic and see what he has to say about that. Wouldn’t that mess with emissions and cause issues? I imagine such a process would have to be completed by way of VCDS.

Good point on vehicle manufacturers recognizing the carbon issue and adding dual injectors to each cylinder. My 13’ F150 Ecoboost only had a single injector for each cylinder and was prone to build up. I believe in 2015, along with a new aluminum body design, the F150 Ecoboost motors were redesigned with a dual injector setup as to achieve the valve “wash down” that is achieved prior to direct injection designs.

Not sure if the newer Q7’s also have this dual injector setup, but I imagine that they do. Unfortunately mine is an 08’ so only single injector for me

Unfortunately I don’t regularly travel long distances at all, sometimes not even a mile so the engine isn’t even at normal temp before I come back home. I’m a firm believer in Lucas fuel additive to keep the injectors nice and clean but I know it does nothing for the intakes on these single injected FSI motors. Always supreme fuel, never 87 octane regular. Either way I know I’m still going to build that carbon right back up but I have a strong feeling I will develop other issues long before I build up that amount of carbon again. That’s 150,000 miles of carbon build up and unknown ownership history prior to me buying it, so I have no idea how it was driven the last 10 years or so.

What about adding catch cans to these? Any thought there? These are not turbo so I don’t have intercooler sludge to worry about but PCV vapors still build up.
Willgatlin25 is offline  

Thread Tools
Search this Thread
Quick Reply: Misfire Cylinder 2 - Please Help


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: