P0302 - 35-00 - Misfire Detected

Glenn71

Member
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:
Audi_A2_identification.jpg

And this is the old spark plugs, the one who is more gray is from cylinder 2:
sparkplug.jpg
 
Last edited:
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
 
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.
 
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.
20170411_214811_1.jpg
 
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


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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
 
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


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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


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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
 
We have still problem with the car. We have changed the valve seal, and many other things, and we have changed the wire harness that goes from the ecu to the engine.
That did not help. I have purchased a used ECU from ebay but we are having problems getting the skc pin from the ecu.
So we think maybe it is the ecu that has given us trouble. We have ordered kkline cable from ebay and will see if that can read out the skc from the ecu.
 
just to confirm, when you changed the harness from the ECU to the engine - did that include the wiring to the coil packs themselves? These harnesses have been known to be problematic.

Very strange and I'd imagine frustrating issue. Good luck on resolving and let us know if you do.

Nick
 
Hi Topsie,
Yes that included the wiring to the coil packs also.
This is the readout from VCDS:

2 Faults Found:

17961 - Barometric / Manifold Pressure Signals
P1553 - 35 - 10 - Implausible Correlation - Intermittent
17912 - Intake Air System
P1504 - 35-00 - Leak Detected

Readiness: 1010 0101

We have used start gas and sprayed all around the engine without finding any leak.

We are also having problem getting the SKC/pin from the car. We need that to change the ECU.
We don't know what has been done with the ECU that is in the car so we will use the donor ECU.

We have tried with Vag-Tacho but that did not work on this car.
Is there anybody who have any luck with getting the SKC from this model?

Regards

Glenn
 
you should be able to read the SKC from the instrument cluster, it is the same SKC code as the SKC code in the ECU

I have used VAG Commander to read the SKC code, but I have only ever done this on a TDI, however the instrument cluster is in principle the same and therefore no reason why it will not work on the petrol models

cheers
 
Stil the same problem with this car:
2 Faults Found:

17961 - Barometric / Manifold Pressure Signals
P1553 - 35 - 10 - Implausible Correlation - Intermittent
17912 - Intake Air System
P1504 - 35-00 - Leak Detected

Readiness: 1010 0101

This is by far the worst purchase I have ever done. :(

We have used a smoke tester at the inlet to see if there is any leak.
And we used the smoke tester with compressed air, and no leaks. :(

Now we don't know what to do. We have tried everything that we can think off.
 
I bought an a2 1.6 fsi with a misfire. Turned out that the injector that had been replaced by the previous owner was defective. Changed the injector and all is ok. Do all your injectors have the same part number on them.
Brian
 
I have no misfire on cylinder two anymore. I delivered the car to a Polish car mechanic and he have had my car for a week and he called me today and said that my car was fixed. It was the throttle house. He ordered a new one and changed it. He have ordered another one also because the idle is a bit low. And that is because the throttle house he got was for a automatic gear, so I will get a new that is for an manual.
So I will pick the car up tomorrow. :D

All the things we have done with the car and all the parts we have changed I will have a car for many years now.
There is still a couple of things that I will need to do with it but that has nothing to do with the engine. :)
The sunroof is not working so that will be fixed. And there is an error message with the air-condition that need fixing.
The aluminium wheels need to be sandblasted and spray painted.

But that is just nice to do, consider all the work that has already been done. :)
 
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