Misfire/Rough Idle when start in cold Wheater

[Luis Hernandez]

I have a 2000 VW new beetle that i've had for about 3 months and i've done lots of work to it, but my bigest concern now is when i start the car in cold temperatures. it misfires and idles rough for about 10 min or so a check engine light comes on during that time and is always a P0300 (random Misfire)< I changed plugs and wires and i have also ran a fuel injector treatment to clean out the injectors, i used the NGK wires because of the thicker insulation after someone told me the problem was lack of insulation on the old wires. PLEASE Help.

[IndyTom]

Originally Posted by Luis Hernandez

I have a 2000 VW new beetle that i've had for about 3 months and i've done lots of work to it, but my bigest concern now is when i start the car in cold temperatures. it misfires and idles rough for about 10 min or so a check engine light comes on during that time and is always a P0300 (random Misfire)< I changed plugs and wires and i have also ran a fuel injector treatment to clean out the injectors, i used the NGK wires because of the thicker insulation after someone told me the problem was lack of insulation on the old wires. PLEASE Help.

Did you gap your spark plugs? I think a lot of people overlook this very important part about changing plugs. If the gap is too wide it will cause missfires. Not sure about the 2.0 engine but on the 1.8 the gap should be .032 or if you are chipped .028.
Check your plug gap. If that isn't it than it could be the coil or a vacuum leak. Check the hoses for brittleness or breakage. Those old hoses don't last forever.
Good Luck to you!

[Luis Hernandez]

Well, the gap on the spark plugs is OK, the only thing i can think of is the coil pack i would just hate to spent the money if thats not the problem, Vacum leak? would a vacum leak affect the car only in the morning and in cold weather only? how could I test the coil?

[IndyTom]

Originally Posted by Luis Hernandez

Well, the gap on the spark plugs is OK, the only thing i can think of is the coil pack i would just hate to spent the money if thats not the problem, Vacum leak? would a vacum leak affect the car only in the morning and in cold weather only? how could I test the coil?

Well, if it is the coil it would be missfiring all the time not just when it is cold out or in the morning. Sounds more like an emission issue. Certain valves open up when cold and close when the engine gets warm. So YES, a vacuum leak could most definitely effect your engine when cold and not when warm. Take the Plastic cover off and check the vacuum hoses. One in particular tends to dry rot and break.


That one to the Fuel Pressure regulator will most definitely effect your driving performance and cause misfires.

[IndyTom]

You could also try and clean your MAF and your Throttlebody.
When the car is running in the morning you can try and spray a fine water mist on the coil and see if it arcs or if your motor falters. That would be a good sign that the coil is bad. Another issue are the O2 sensors.
Hope you find your issue soon!

[Luis Hernandez]

UPDATE, I went ahead and checked the hose going from the fuel pressure regulator to the intake and found the hose bent at the spot conecting to to the intake and i also notice a small crack in that section of the hose, i cut of that part that was bent and reinstalled it the propper way, would this small crack cause all that trouble? I will have to wait for the temp to drop again so that i can test it and see if it worked or not, give me some tips on how to test the MAF sensor or the 02 sensor. And also thanks for all your help so far, hope we can get it fix quick.

[IndyTom]

Originally Posted by Luis Hernandez

UPDATE, I went ahead and checked the hose going from the fuel pressure regulator to the intake and found the hose bent at the spot conecting to to the intake and i also notice a small crack in that section of the hose, i cut of that part that was bent and reinstalled it the propper way, would this small crack cause all that trouble? I will have to wait for the temp to drop again so that i can test it and see if it worked or not, give me some tips on how to test the MAF sensor or the 02 sensor. And also thanks for all your help so far, hope we can get it fix quick.

Yes, a crack or split anywhere along that hose can cause all sorts of issues since it is the vacuum line to your fuel pressure regulator and with out proper vacuum you don't have proper fuel pressure. I would replace that entire hose because if one part is faulty then you can bet that the rest isn't in much better shape.

Here is a basic link to MAF sensor testing. Part 1 -The Basics of Testing a MAF Sensor.

http://www.google.com/url?sa=t&rct=j...iW8bDdwxhFFZVQ

VWVortex.com - MAF sensor testing


I wouldn't worry about it just yet. More than likely your problem was the faulty vacuum hose. If it still acts up then I would proceed with further diagnostics.
The O2 Sensors without removal can only be diagnosed with a VAG com diagnostic software. Again, I wouldn't worry about it until we eliminated the other possibilities.

[n7plus1]

vacuum leaks CAN cause misfires. gl

[daughtersbeetle]

Following this post, to see what you find out

[Luis Hernandez]

UPDATE Temperature was about 40 degrees this morning and the beetle act up again misfire/rough idle and check engine light with the ramdom misfire code, i went ahead and and spry the mist water on the coil pack while it was acting up and the pack did not arc or anything,i also loooked for any noise/vacum leacks and didn't notice anything. geting frustrated with this issue.

[IndyTom]

I feel your pain. Apparently this is a common issue with the 2.0l engine. On the Vortex there is an entire thread of several people having the same issue. The OP replaced the coil pack, the MAF (Twice), the injectors, the plugs, the wires, the O2 sensors and and and.... After one year of messing with it he still had the same problem. Once it warmed up the engine was fine and after a year and spending who knows what kind of money on needless repairs he finally gave up.

[IndyTom]

I think your 2000 VW 2.0 has the AEG engine code?

Anyway here is a coil for the AEG engine which isn't too bad in price:
Volkswagen New Beetle 2.0 > Search > Coil > ES#888 Ignition Coil - 032905106B

Do you have a friend with a similar car? Doesn't have to be a Beetle. A similar year Jetta or Golf will do. Perhaps you can swap out the coil pack to see if it will improve your situation before spending money on a new coil.

How are your spark plug wires? Also I would recheck the plugs and double check the gap. It is probably okay but it doesn't hurt to double check.
Take the MAF sensor out and gently clean it with some MAF cleaner. You can try and clean your Throttlebody and see if that helps a bit. I would find someone with a VAG com in your area. The Vag com will give you a much more detailed reading than just the basic OBDII scanner.

Sorry for your troubles. I wish and hope that you will find the problem soon. I know it can get very frustrating.

Good Luck!

[Luis Hernandez]

I have also spent a bunch of money on the car, i purchased the car with a small fender bender so i had to do some body work, new fans, radiator, ac, head gasket, timing belt, water pump, serpentine belt, spark plugs, wires, oil pressure switch, oil pump and screen and on top of all npw i taugh it w as ready and this issue came up but i am willing to fix it the right way, could this be a computer issue? Does anyone know anyone with the same problem?

[Smileybug]

I wonder if it could be an issue somehow related to the coolant temp sensor? I know it can cause crazy things to happen when it goes out, and it doesn't always throw a code. Just trying to think of things that will be related to outside temperatures.

[IndyTom]

Originally Posted by Smileybug

I wonder if it could be an issue somehow related to the coolant temp sensor? I know it can cause crazy things to happen when it goes out, and it doesn't always throw a code. Just trying to think of things that will be related to outside temperatures.

Could be a lot of things. Coolant sensor? maybe but unlikely.
O2 Sensors, Catylitic Converter, Crank positioning Sensor, Thermal 112C Sensor (unlikely), etc etc. The list can go on and on.

If the car was in a fender bender maybe the coil does have a hairline crack somewhere. They do break fairly easily. Just hate to have you replace things at random. If it's not a vacuum leak than my money is on either the coil or O2 sensor, then MAF or the ECM itself. I would see if you can find someone with a Vag com and have it scanned. It may reveal more than just a basic OBDII scan can.

[Luis Hernandez]

UPDATE - Just picked up a Coil from a friend who owns a shop and did a swap on a beetle last week who's engine trew a rod so the coil is good just to try it out, I will swap it with mine when i get home and hopefully this will do the trick tomorow, the reason why Iam inclining more towars the coil is because this morning it also picked up a code for Cylinder #1 and 4 along with the random misfire and I read that the coils for this cars share the spark between 2 cylinders at a time so if that is true it somehow explains why only cyl #1 and 4 are missing and not the others, well i would also like to know how to test my coil with a digital meter (dont know if that's possible) if this works I will buy the new coil to fix the problem if not then i will have to start looking at the MAF sensor to see if that's it. Thank you for all the help and interest in my issue hope we can get this fix and help others with the same problems.

[Luis Hernandez]

Update - i started the beetle this morning with no problem, the temperature was at about 40 to 45 degrees and the car started up fine with no misfires, who would of though the problem was a bad ignition coil since the issue was only in the morning and in cold weather temperatures, i had ruled out the posibility of it being the coil because the car ran fine after it warmed up, hope this can be really helpful to people having the same issue, thanks for all your help guys.

[IndyTom]

Originally Posted by Luis Hernandez

Update - i started the beetle this morning with no problem, the temperature was at about 40 to 45 degrees and the car started up fine with no misfires, who would of though the problem was a bad ignition coil since the issue was only in the morning and in cold weather temperatures, i had ruled out the posibility of it being the coil because the car ran fine after it warmed up, hope this can be really helpful to people having the same issue, thanks for all your help guys.

GREAT NEWS! Glad you got her fixed!!!