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Discussion Starter #1
My wife's new beetle has a misfire. I put new coil packs and ngk copper plugs in it from ecs tuning and it went away for about 3 weeks. The writing harness for the coil packs is not dry or cracked at all do I do not suspect it's the problem. Is there anything else i should look at? I'm stumped. Should i put iridum plugs back in it?

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Do you have a scan tool that can read real time data?

You need to read your fuel trims and engine coolant temperature.

My guess if you are having cold start misfires that are triggering random misfire and possibly cylinder specific misfire codes.

You need to check the small black & white check valves on the driver half of the engine under the top engine cover. Also check around the purge valve and rubber boot at the rear of the engine.

Most of these cars have thermostats that have soft failed, they rarely trigger any trouble codes or if they do they are very sporadic. The engine should run at a consistent 200-205F, if the thermostat has soft failed you will see 180-185 which is too cold. This can cause more build up on the back of the intake valves and in the intake ports.

You have a Galaxy Note, so this is a Andriod device. I would purchase the Torque Pro app for $5 and the ELM327 Bluetooth ODB adapter on Amazon for $15 then you can read real time data on the car, CEL codes and clear codes.

You may also need a number of Techron treatments, but do not waste your money on this until you can confirm the engine operation temperature is correct. Again an cold engine runs richer and has more carbon build up.
 

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My money is that your thermostat is bad and you have vacuum leaks somewhere around the intake area. Also your dipstick tube is likely cracked at the base. The crankcase is also part if the intake air path as well.

If your fuel trims are above 3% then you have vacuum leaks somewhere that need to be addressed.
 

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Discussion Starter #7
Well do. It should be here by Friday. I was just wondering...if the car is misfiring because of the thermostat issue it would be because the plugs are fouled right? Should i get an new set of plugs anyway? It's a pretty hard misfire....It's a pretty hard misfire

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What I have been finding is cars that chronically run a low engine temp tend to have the following issues:

1. Poor fuel economy
2. More chance for sludge buildup in crankcase due to oil not able to "cook" off additional water vapor and excess fuel dilution. Cars that have shorter drives are more adversely impacted. This also accelerates engine wear as well.
3. Greater carbon build up in cylinders on piston domes, in intake ports and on rear surface of intake valves. Carbon that has been "cooked" acts just like a sponge. After the engine is shut down and the carbon dries out, at the first start of the day the carbon acts as a sponge and will absorb fuel until the carbon is wet to the point it will not absorb additional fuel. During the point the carbon acts as a sponge, it will lean out the fuel mixture causing lean misfiring, unstable engine idle and possible stalling. Once the carbon is wet, it is almost like it does not exists. This is why many times if the engine runs poorly on cold start, then stalls, on restart the engine may run just fine, the carbon has absorbed all the fuel it can and will no longer lean out the fuel mixture. On these engines with 3 intake valves the challenge is a bit greater.

What I have found when the engine has been running chronically cold, if a new thermostat is installed and you run 4 Techron treatments things will start to improve over time as you continue to drive the vehicle.
 

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Then if you likely only have a misfire at idle, then you probably have a vacuum leak/lean fuel mixture.

If the misfire happens under load and while cruising, then likely a secondary ignition problem, plugs, coils?

What gap are you running on the spark plugs? Did you check them before you installed them? Forced induction engines usually need smaller spark gap due to the increased combustion pressures.

Do you have freeze frame data from the misfire codes? This would be helpful.
 

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Discussion Starter #11
I'm still waiting for my scan tool thing to show up...I'll get you freeze frame data as soon as i can. It feels like it's a dead hole at idle but rpm seems to help a little. I just put new plugs and coils in it from ecs tuning. I set them at 32 thousandths i believe. It ran perfect for like 3 weeks after i changed those parts and it all of sudden developed a hard misfire. Not like gradually, it just started doin it all of a sudden. Check Engine Light flashes and everythin.

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misfires

last time I had misfiring during cold starts it wind up being the NGK plugs cause that was the only parts I had just replaced the previous week. I went back to Autolite platinums at (.032) and Babyblue purrrs like a kitten.:D my 2 cents on this. good luck man.
 

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February?! Where did you order it from?!
 

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Time to hit Auto Zone, Advance, O'Rielly, Pep Boys or Aamco for a free code reading.

Some of the ELM327 ship from Asia, but mine came quick via Amazon, this is why you see if the item is Fulfilled by Amazon or someone else before you pull the trigger.

This one likely to take a WHILE?

Note shipped and sold by Overseafortune!

Soliport ELM 327 Bluetooth OBDII OBD2 Diagnostic Scanner : Amazon.com : Automotive


This one would likely show up earlier than the one above?? See notice about Fulfilled by Amazon.

Koolertron F-12 ELM 327 OBDII PC Car Diagnostic Scanner : Amazon.com : Automotive

You spend another $2.53, but are more likely to receive it in less than 1 week.
 

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Discussion Starter #16
Haha apparently it's coming from the moon. I got a buddies scan tool. It has P0301 cylinder one miss fire. I bought a set of platinum plugs to put in it. I also have the old coils to try. I'm gonna try swapping since parts now and see what happens...at least i know where to start. It's a pretty hard miss fire...

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Discussion Starter #17
So it ended up being the coil. Swapped an old one back on misfire went away. Put the new one back in just to check, misfire came back. I put platinum plugs in it and took the copper ones out after i found out they don't last in turbo engines. So as of right now it's running perfect. When i get that scan tool I'll make sure the thermostat is working correctly and the next time it breaks down I'll be back for more help haha. Thanks guys.

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Discussion Starter #20
Got my ELM. The cars been running good. Plugged in the ELM to check it out anyway. The LTFT is 8% and the engine temp sits at 170. Looks like I need to put a thermostat in it?

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