Will not stay idling, will not run but between 1k-2k rpm on 2000 Volkswagen Beetle

Ok, it started out not idling when it was cold and then after it warmed up it would not start after letting it set for approx. 30 min. to 1 hr, so I replaced the fuel filter since it has 75,000 miles on it. It seemed to have fixed it for awhile, but after a couple days it started doing it again. I put a scanner (code reader) on it and it showed P0322, P0134, & P0102 so I replaced the Engine speed sensor, Mass Air Flow sensor, and the O2 Pre-converter sensor. This seem to help it idle and was running good, better than ever. After running it down the road about 5 miles it started cutting out and bogging down. Then it picks up. It was showing a misfire P0300, P0301, & P0303, so I replaced the plugs and it is doing the same thing now, but it is not showing any codes in the ECM. The fuel injectors are still clicking, assuming they are working OK. What do you think will cause it not to idle, bogs down not going over 2000rpm, and if you hold the accelerator steady the engine fluctuates?

Asked by for the 2000 Volkswagen Beetle
For P0300, P0310 and P0303 you need more than just plugs. Usually you need to replace the wires as well. Also look at the coil pack, because they often become burnt from misfires. I have had the terminals come off in my hands when I have replaced the wires on 2.0 VWs. (AEG motor)
What rpm does the car not want to go over when you just rev it with out it being in gear? I ask this because there is a rev limiter built in to the system. Do you have any more Check Engine Lights? Because you had so many codes and problems, i.e. Oxygen sensor, Mass Air Flow Sensor, Crank Sensor and 3 misfire codes you may have over heated and damaged the CAT which will cause the car to bog under power. Can you do a vacuum test at 3000 rpm? Do you know what that is? It is a way to tell if the CAT is plugged. I can go over it with you in detail if needed. It isn't too hard and it can tell you if the CAT is plugged.

The best way to check a coil pack is with a spark tester. Ohm checking is good to a point, but I have seen , recently, where, for example a Mercedes coil ohm checked fine, but the spark blasted right out the side of the coil and onto ground. It never reached the plugs. It would idle just fine but under load, it misfired really badly.
So if you could get a 40k spark tester ( easily obtained at a decent parts store )which is basically a spark plug with a wide gap and a ground clip. Your coil pack should fire that bad boy with out even breathing hard because they are rated at about 80k. remember, 2 coil terminals fire at once so BE CAREFUL so you don't get scorched. I would only test one terminal at a time and leave the other wires connected. It will be pretty obvious if there is a problem. The spark will be weak and or very inconsistent. Rev the engine or even have someone power brake it ( that means give the engine power in drive with your foot holding the car back, it can be done with a stick for a little while while slipping the clutch )Best of luck to you.

So, you said that you replaced the wires, what type did you use. This is very important. Only a few wire sets will work OK on this vehicle. It is interesting that it ran fine for awhile and then stalled with the same codes. It sounds like there was some difference made with the wires. Is this true? Is the weather wet and snowy where you are? I ask this because coil pack problems tend to get worse in this type of weather. Especially as the coil pack heats up, it will tend to short to ground.
I don't think it is the CAT because it will be running like a top then when you let off the accelerator the rpm just drop to idle and you have nothing on the accelerator for awhile then all of a sudden it's back running good. It is very speratic.
Also when it is running there is plenty of exhaust coming out of the tailpipe, but at times I think it is burning really rich with a strong smell of gas out the exhaust. Kind of like the choke is stuck.
I will go ahead and get the plug wires changed and check the coil pack. Is checking the coil pack with an ohm meter between terminals 1 & 4 then terminals 2 & 3 (should have 4000 to 6000 ohms)a good indicator if the coil pack is bad?
Unplugg your maf sensor and see if it straightens up. I have the exact problem, had a vacuum hose to the brake booster cracked right at the check valve and when i fixed it, problem still persisted. Unplugged the maf and like magic it starts running better than ever
3 answers 3 comments
You need to accurately diagnose this before replacing parts. To do that you need a scanner that is able to access the various address locations. For example address 032 will give data as to your fuel mixture , learned values etc.That is the basis for replacing a MAF. Basics such as fuel pressure and volume , ignition , (preferably checked with a scope as the problem occurs) and mechanicals including compression , cam timing and integrity of the intake tract (preferably checked with a "smoke" type tester) all need to be 100%.

I got the spark plug wires replaced yesterday and started it up. It was running fine until my step daughter started driving it again and left her stranded at school. I picked it up and it was running same as it did before. Checked the codes in the ECM because the check engine light came back on and was showing the missed fired codes again (P0300, P0301, P0304, & P0303).
I don't have a spark tester handy but I do have a 1998 VW beetle that has a 2.0L in it that has been wrecked but the engine runs good in. I'm going to go ahead, probably this weekend and swap out the coil pack between the two. I appreciate your time and comments. I'll keep you informed on my progress.
I have an 04 NB... Last summer I was having problems with my car just stalling out and not wanting to restart. It would crank like crazy, but not start. And, like you did, I left it alone for awhile and went back to it and Bam, normal(ish).... Turns out it was my Crankshaft Position sensor. not very expensive, super easy to do. 5 min job, once you locate it!! My big red truck on the diagnosis, was that it was only a problem if engine is hot. Good Luck!