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Thread: P0302 - 35-00 - Misfire Detected

  1. #1

    P0302 - 35-00 - Misfire Detected

    Hi everyone, I am new to the forum and I badly need some help!

    I bought an Audi A2 1.4 2003 Petrol for my wife.

    When I bought the car the engine warning light was already present. The previous owner meant that the engine issues were no big deal and that car handled well even if the engine light comes on. When I drove the car home the engine warning light came on, and the car drove terrible, lack of power. I had to pull over and restart the engine many times to get the warning light to clear so that I was able to drive home. When warning light clears, the car ran normally.

    The previous owner had the car into repair several times because of the engine warning light, but the repair shop was never able to solve the problem. They had done a lot of diagnostic and even changed the ECU and 1 coil/coilovers.

    I have very little experience when it comes to repairing cars and I am on a budget. That said I got a friend which used to be a car mechanic that helps me out. He also has access to VCDS, but as he explained his skills using VCDS is not that good.

    VCDS reports that there is a misfire cylinder 2 (P0302 - 35-00 - Misfire Detected). I can drive the car fine, but very often when car come to a stop still, the engine warning light comes on and the car then runs terrible. This also happens when I start the engine and let it idle for 1 3 minutes without hitting the accelerator. If I start driving right away, there is no problem as long as it does not idle for above a minute or so. What we have done so far:

    - Changed ECU (Second hand ECU)
    - Replaced injector on cylinder 2
    - Swapped coil/coilovers between cylinder 4th and nr 2, also from 3th and nr 2.
    - Replaced knock sensor
    - Replaced spark plugs
    - Replaced fuel filter
    - Regular service, oil, oil filter, air filter.
    - Compression tests on all cylinders:
    o Cylinder 1 = 16.2 Bar
    o Cylinder 2 = 17.1 Bar
    o Cylinder 3 = 16.8 Bar
    o Cylinder 4 = 17.8 Bar
    - Fuel pressure and fuel pump delivery rate:
    o Fuel pressure while engine idle: 47 psi
    o Fuel delivery 1600 cm3 in 30 sec (battery 12.80 V, ignition off, remotely/manually run)
    - Inspected the engine loom wiring harness. Measured resistance between the different connectors such as to coils and injectors. This was just a quick and dirty check to see if we can verify if there was some resistance difference it the readout between the different connectors/pinouts for the units, no difference was noticed.
    - Tried to spray starter gas around the intake manifold looking for leaks, but no rise in idling.
    - Throttle housing calibration done using VCDS, OK
    - Checked and verified timing belt alignment, OK
    - Cleaned MAF sensor, OK
    - Coolant sensor, OK
    - EGR valve calibration done using VCDS, OK

    We noticed that there was a color difference while changing the sparkplugs. Sparkplug on cylinder nr 2 was much darker than the others. We used a flashlight inspecting each piston through the sparkplug hole, and we noticed that the piston on cylinder 2 was a little wet compared to the others.

    When we disconnect the fuel injector on injector 2 while the car is running, there is just a slight difference in how the car is idling. When we disconnect any other injectors there is a very clear difference in idling. When my friend used VCDS and advance measuring blocks selecting Lamda readout, misfire cylinder 1-4, he thought that the lambda sonde/O2 readout was variating too little, close to 0 all the time. He decided to disconnect the O2 sensor. When disconnected O2 there was no misfire registering in VCDS and the engine was idling much better, no engine warning light. My friend had a new aftermarket O2 sensor lying around which is for an Audi A3 1.6. The wiring color code is the same as the original car O2 sensor/connector, so we decided to replace the O2 sensor with the one for the Audi A3. The readout in VCDS for the O2 sensor now showed a much more variable readout than before, but the misfire count on cylinder nr 2 started again, and as soon as it reached around 85-100 misfires the engine warning lamp came on again and then also the O2/Lamda readout stopped and went to 0. When we clear the TDC (misfire cylinder 2) for the engine while engine is running, the O2/Lamda readout start displaying values again, but so does the misfire counts for cylinder 2, and then engine warning comes on and O2 readouts stops again.

    So we concluded that if O2/Lamda is disconnected there is no misfire readout in VCDS, the engine runs smoother and no engine warning light.

    My friend is suspecting that cylinder nr 2 may have leakage problem in the intake manifold, or there is some kind of vacuum leakage (have not been able to trigger the problem using starting gas), maybe EGR issue (do not know is there is EGR tube for all 4 cylinders, or just one common tube/vent)

    I sincerely hope that someone here is able to point us in the right direction, maybe there is something that we are missing or overlooked.
    LOG from VCDS:

    Address 01: Engine Labels: 036-906-034-APE.lbl
    Control Module Part Number: 036 906 034 CA
    Component and/or Version: MARELLI 4MV 5949
    Additional Info: WAUZZZ8Z73N006323 AUZ7Z0B2128047
    1 Fault Found:

    16686 - Cylinder 2
    P0302 - 35-00 - Misfire Detected

    Readiness: 1010 0101

    And here is the vehicle identification:
    Click image for larger version. 

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    And this is the old spark plugs, the one who is more gray is from cylinder 2:
    Click image for larger version. 

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    Last edited by Glenn71; 09-04-2017 at 08:54 PM.

  2. #2
    Join Date
    Oct 2016
    Location
    Saltash, Cornwall, UK.
    Posts
    240
    What are the fuel trims doing? If there is a vacuum leak near cylinder no.2 it should be picked up with the air/fuel adjusted accordingly, the fuel trims can show if you have an air leak by showing if the ECU is increasing or decreasing the amount of fuel in the mix. (Loads of really usefull youtube videos on this)

    What doesn't make sense is that the car will not adjust fuel trims for individual cylinders - it senses and treats all 4 cylinders as 1 bank. Is the injector definitely fitted correctly with new o-seals?

    What happens when you disconnect the MAF sensor?

    If the MAF sensor is reading incorrectly it will also give the same symptoms as the o2 sensor.

    Nick
    2003 Audi A2 1.6 FSI Sport | Bi-Xenon Projectors | Climate Control | Front Fogs | Headlight Washer Jets | Heated Mirrors & Windscreen Washer Jets | Heated Seats | Symphony II | Vanity Mirrors | PDC | Rear Electric Windows | Auto Dimming Rear View Mirror | DIS | Working OSS | Rear Cup Holder


  3. Users that liked this post:

    Glenn71 (17-04-2017)

  4. #3

    Talking

    Quote Originally Posted by Topsie View Post
    What are the fuel trims doing? If there is a vacuum leak near cylinder no.2 it should be picked up with the air/fuel adjusted accordingly, the fuel trims can show if you have an air leak by showing if the ECU is increasing or decreasing the amount of fuel in the mix. (Loads of really usefull youtube videos on this)

    What doesn't make sense is that the car will not adjust fuel trims for individual cylinders - it senses and treats all 4 cylinders as 1 bank. Is the injector definitely fitted correctly with new o-seals?

    What happens when you disconnect the MAF sensor?

    If the MAF sensor is reading incorrectly it will also give the same symptoms as the o2 sensor.

    Nick
    Thank you Topsie.

    After I read your post I searched for fuel trim VCDS and found some great information. The value does changes and goes to more then 10% before it get adjusted.
    But I think there is something more wrong with the engine. I will poste some picture later that I took today after we took of the intake manifold.

    Thanks again for the information you provided, it's always great to learn something new.

  5. #4
    Hi everyone,
    Some new updates.

    Today we removed the intake manifold, we discovered that the intake on cylinder number two was oily and brownish.
    The other intakes were nice and clean and so were the valves.

    Further inspection reviled that one of the valve on cylinder number two was covered in oil/carb.

    We have not dismantled the valve cover but it seems like the valve guide or at least the valve seal is broken.
    Since its oil on the valve rod we suspect the cylinder number two is at least burning oil, will this result in misfire and is it possible that it draw air through the valve seal?

    Please see the included pictures for details.
    Click image for larger version. 

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  6. #5
    Join Date
    Aug 2015
    Location
    St Annes on the Sea
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    1,213
    Quote Originally Posted by Glenn71 View Post
    Thank you Topsie.

    After I read your post I searched for fuel trim VCDS and found some great information. The value does changes and goes to more then 10% before it get adjusted.
    But I think there is something more wrong with the engine. I will poste some picture later that I took today after we took of the intake manifold.

    Thanks again for the information you provided, it's always great to learn something new.
    Burn oil is a yes as the cylinder draws in oil it will suck on some oil from the valve stem oil seal but this is unlikely to cause a misfire Once the valve is closed then the oil leak is closed to the cylinder so would expect this not to cause a problem


    Sent from my iPhone using Tapatalk
    Paul (Depronman)
    1.4 TDI 2001 287,347 miles and still going strong

  7. 2 users that liked this post:

    Glenn71 (17-04-2017), steaman (12-04-2017)

  8. #6
    Join Date
    Oct 2016
    Location
    Saltash, Cornwall, UK.
    Posts
    240
    Very doubtfull that burning oil alone will cause a misfire unless in great quantities (thick blue smoke from exhaust) and even if air was being drawn in through the inlet valve seal / guide it would not matter, that air is metered via the PCV system, but still more likely to just burn lots of oil.

    Either way, I'd change the valve stem seal (it is manageable with the head on - again youtube is your friend) and see where that takes you, though i'd also be interested in seeing the condition of the valve seat. (Carbon build up on the inlet valves can indicate blow-by ie. damaged seat/bent valve - though your compression results are good so unlikely)

    Nick
    2003 Audi A2 1.6 FSI Sport | Bi-Xenon Projectors | Climate Control | Front Fogs | Headlight Washer Jets | Heated Mirrors & Windscreen Washer Jets | Heated Seats | Symphony II | Vanity Mirrors | PDC | Rear Electric Windows | Auto Dimming Rear View Mirror | DIS | Working OSS | Rear Cup Holder


  9. Users that liked this post:

    Glenn71 (18-04-2017)

  10. #7
    Join Date
    Sep 2009
    Location
    North Yorkshire Coast
    Posts
    138
    Have you changed the plug leads?

  11. #8
    Quote Originally Posted by Hank View Post
    Have you changed the plug leads?
    It's coils.

  12. #9
    Hi I have the exact same fault , I have had the head reconditioned and new piston rings I have also done all the same things you have ,and I still got the same problem would love to know if you solve it thanks steve


    Sent from my iPad using Tapatalk

  13. #10
    Quote Originally Posted by Stevo 191 View Post
    Hi I have the exact same fault , I have had the head reconditioned and new piston rings I have also done all the same things you have ,and I still got the same problem would love to know if you solve it thanks steve


    Sent from my iPad using Tapatalk
    Hi Steve,

    There seems to be a common fault on this model. (engine light)

    We will change the valve seal, and check the exhaust manifold.
    Change the seals from the things we have taken apart, and see if that changes anything. (fals air)
    If not, we have to check if it could be the wires. I have bought a used wire harness from ebay.
    On my wire engine harness there is some soldering on the wire to the injector on cylinder two.
    We have changed part of that wires that was soldered. So it should be alright.

    We will also check for leaky EGR valve.

    So I will keep you updated with our progression, and please feel free to share anything you find on your own car.

    Regards

    Glenn

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