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Discussion Starter · #1 · (Edited)
Hello Guys,

I really appreciated your help.

Cars is a 2009 Jetta MK4 2.0L with only 51,500kms (The Jetta MK4 is still in production in Mexico under the name Jetta Classic)

Just yesterday, when I started the engine in the morning it misfires stumble/hesitate and can fill a small shake in the engine, sometimes fill like a hiccup at idle. If the AC is on, the problem is a little more worst.

This was at my building garage, I was having my door open and I can fill a strong fuel odor (like when is very rich) I am pretty sure I have start the engine before in other occasions with my door open and never smell that strong fuel odor.

As soon as the engine get semi warm (engine not quite up to temp) the misfiring goes away and the car behave like nothing happened and runs perfectly. At Idle I still fill sometime the hiccup.

There is no illumination of the Check Engine Light..

Scan for codes with my OBD FUSION and it throw P0302 Cylinder 2 Misfire Detected

My car does not have a secondary air pump that goes on top of the four corners coil pack so I can easily see the coil pack.

So I went a make the test of using a spray water bottle to spray over the coil pack and there was no misfires neither any electrical arcing.

I done this test with the engine at idle and also with some body helping me pressing the gas accelerator to rise the RPM. I spray very heavily and there was not a single hiccup.

I then use a garden hose to throw a lot of water over the coil pack and neither misfired.

I have not removed yet the plugs to check them but these plugs are almost new. I installed new 101-000-033-AA OEM plugs at 41,500 Kms (Does was the same part number plugs I remove and the same part my VW dealer says my car use with my VIN No.)

Any advice what other test I can perform to pin point what is the exact part I need to change? Or what other test I can perform with the OBD Fusion code scanner? Maybe I can make a test when starting it in the morning before the engine get warmer.

I really don’t want to throw money changing and changing parts.

Thank you for your help and time.

Regards,

Isaac


 

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Good question! It would be interesting; to see what your trim levels are and if there are any pending codes. These could give you some clues; as possible reasons, for the drivability problem.

Fuel Trim Info - Ross-Tech Wiki

16686/P0302/000770 - Ross-Tech Wiki

Typically, it will throw a code but a bad coolant temp sensor, has caused the problem you describe. You could use the OBD II fusion and see if the coolant temps, seem normal.

It sounds like; you did the typical testing for the cracked coil pack problem but here is a link to a good thread, anyway:

http://forums.vwvortex.com/showthre...eshooting-Coil-pack-on-2-0-AZG-AVH-BEV-or-BBW

Check your trim levels (+ or - 10% is said to be normal), pending trouble codes, freeze frame info and we will go from there.
 

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Discussion Starter · #3 ·
Hey Billymade,

Thanks for your reply and help.

I already changed the coolant temp sensor like 2 month ago, but when I started the engine with the bad coolant sensor it was a big stumble/hesitate and the engine shake was huge. There were no OBD codes during this problem. I changed the Coolant sensor and it fixes the problem.

Now the misfires stumble/hesitate is a small shake in the engine and you can fill like a hiccup at idle..... And this time it throws the P0302 but as soon the engine get warmed the shakes goes away and the car runs normal.

What exactly you recommend me to program on the OBD Fusion to see in graphics.

The OBD Fusion allows me to set 4 SAE PIDS but I am not sure which ones you want to see.

Here are the photos that show you what SAE PIDS I can program in the OBD Fusion. Can you let me know which ones to program.

THX,

Isaac









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I would try changing your brand of gas and see if that helps. I get similar symptoms with just one brand (Valero here in the US). For me, the problems gets worse the longer the car sits without running. It will start to show up at about 2 days and will be to the point it will barely idle on startup at 7 days.
 

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DO NOT TRY TO GRAPH WITH OBDFUSION, IT IS A WASTE OF TIME.

If you have codes, post Freeze Frame data.

Run a Diagnostic Report while the engine is running and warm and post the info.

Below are some comments for OBDFusion, however, in iOS a few things are different.

First change the MAF reading from Pounds/Min to Grams/Sec, stupid EASY.

Settings, Units, Airflow, choose g/s.

Temp sometimes can be more useful in C vs F, but no so critical.

Settings, Log Setup then set the following:

Logging Enabled - checked

Logging Trigger - choose Trigger at a fixed sample time

Sample Time - choose 1000 msec

Log GPS Items - suggest you unselect it as to not advertise where you live

Select Items to Log - This varies a bit for each car. But here is a list I like to see:

Fuel - do not check any of these 3 items

SAE PID's:

Fuel system 1 status
Calculated load value
Engine coolant temperature
Short term fuel % trim - Bank 1
Long term fuel % trim - Bank 1
Engine RPM
Vehicle speed
Ignition timing advance for #1 cylinder
Intake air temperature
Mass air flow rate
O2 Voltage (Bank 1, Sensor 1) - not all cars have this
O2 Voltage (Bank 2, Sensor 1)
O2 sensor Voltage wide range (Bank 1, Sensor 1) - not all cars have this
Input Voltage read by the scan tool

Before you clear codes, get the Freeze Frame data and email or save the screen shot if this is an option. Freeze Frame data saves about 20+ questions as to what is going on.

Set up a DropBox Free account. DO NOT DOWNLOAD AND INSTALL THE DROPBOX SOFTWARE ON YOUR COMPUTER. When you set up the DropBox account, once you enter your username and password and it prompts you to download the software, just hit you back browser button.

Then enter your DropBox username and password into OBDFusion.

You can then easily upload the Log file to DropBox. Everytime the App is connected Logging is active.

You can then log into your DropBox account, highlight the file you want to share, choose Share and then copy and paste the share URL back here for review.

I can then review the data and graph as needed.
 

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Discussion Starter · #6 ·
Hey jfoj,

Thank for your time and help.

I already program everything you toll me on my iPad with the OBD Fusion.

Yesterday I erase the Malfuntion Code :eek:

I went to start the car right now and belived or not, it started without any shake and there is not codes. I think the car hear us talking :rolleyes:

Please allow me to keep using the car and when it trigguers the problem and codes, I will get back with all the info you requested.

Thank you so much for your help

Regards,

Isaac
 

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Discussion Starter · #8 · (Edited)
Hello Guys,

Just an update.

Since my last post about my problem, the car has work without any problem.

I really dont know why it bother for 3 or 4 days and then the car is working without any problem.

The P0302 code has not comeback:warmfuzi: and engine is working as normal.

I have not removed the spark plugs, I havent done anything. It just cure byitself:roflmao:

If there is any news, I will keep you guys updated.

Thank you for your help

Isaac
 

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Most cold start misfires are not coil related problems.

Cold start is the easiest on the coils and it happens to be the lowest Voltage demand for the coils due to the low combustion chamber pressures and the Rich cold start fuel mixture is much easier to fire/ignite then a Lean warm idle or cruise condition.

Many of the cold start misfires occur after the car has been started for only a short period of time to move the car in the driveway or out to the street when cold, then shut off until the next day or later.

Vacuum leaks are also a prime cause of cold start and start up misfires.

Monitor the warm idle Fuel Trim and perform a cold start 4 minute Log and share the .CSV file here back in the thread.

See this thread for more info on OBDFusion and setting up DropBox.

http://newbeetle.org/forums/2-5-liter-gas/120273-air-fuel-ratio-issue.html
 
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