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Help! What have I done wrong?

2383 Views 20 Replies 5 Participants Last post by  AUDVM
Hello all. New to the forum and need input. I have a 1999 Beetle GLS auto trans with 109k miles. Car is new to me, have owned it for about 1 month. Before I bought it, it had timing belt, water pump and thermostat replaced. Car ran well, however CEL was on; generic code reader gave several codes: P0300, P0301, P0302, P0303, P0304, P0134, P0171, P0455 and P1582. I was able to see arcing plug wires and also found cracks in all 4 terminals of the coil pack (plug wire towers). Plugs were replaced (Denso). Wires replaced (NGK). Coil pack replaced (Beck-Arnley?). Front O2 sensor replaced (Bosch , wiring and OE connector look good). Upon first start up, I have a rough idle, a very strong odor of unburned fuel at tailpipe and a P0301 code. Car runs worse when attempting to drive and CEL now flashing. I have checked all vacuum lines and they appear in good order. Have double checked my plug wire connections. I don't have access to a more advanced scan tool. It seems that something I have done is amiss as the car ran well ( no miss) before and while CEL WAS on, it was not flashing. Please help!
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Maybe got two of the plug wires mismatched. ? This happened to me,and I'm a professional mechanic!
Oh, and by the way welcome to the new beetle.org! :)

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Thanks for your reply. I have rechecked my plug wires at least 4 times to ensure they were correct . Any other suggestions ?
Usually when replacing the spark plugs the connectors for fuel injectors 1 & 4 are disconnected to allow access to the plugs. Were they disconnected, and if so did they get reconnected?

The p0455, while it won't cause your current problem, is for a EVAP system leak and likely will still be present. See this:

P0455 Volkswagen EVAP System Large Leak Detected OBDII Engine Light Trouble Code | Engine-Codes.com

Here is a DIY I put together on checking the EVAP system. Cracked charcoal canisters are the usual culprit for large leaks.

Thanks for the link. Injector wires were removed. Replaced and checked multiple times since. P0455 code has not reappeared but have not driven over about 2 blocks since CEL began flashing. Car runs so badly I don't see how you could drive it anyway. Any other suggestions?
I'd check the wire for plug #1 for continuity. Should be 4000-6000 ohms. If that looks good, pull plug #1 and replace it with one of the old ones and see if that fixes it. I have heard of brand-new plugs not working. If that all checks out, the coil pack should measure 4000-6000 ohms between plug terminals 1 & 4 and the same between terminals 2 & 3.
Will do. I have pulled # 1 plug and visually inspected, can't see an obvious problem but will swap it and see. Will also check resistance and post back ASAP. Thank you.
If the number one plug is wet when you pull it, there is a problem with the ignition. If it is not wet,then there is a problem with the number one fuel injector?

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Well I have tried new plug(s), no change. Wire ohms within spec. Coil pack ohms at 7500, both sides vs old cracked pack at 4700. Would this matter? By the way, replaced coil pack with another new one, same symptoms. Fuel injectors are "working" ie you can hear/ feel the "click". Seems to have no miss above 2000 rpm, but misses/ stumbles off idle badly. Check engine light flashing, now has shown misfire codes for cylinders 1,2,4. WHAT NOW!!!!!!!! I am at a total loss. Anyone help! Please!
Here is are the proper connections for the coil pack, along with the resistance spec:

Volkswagen Workshop Manuals > Golf L4-2.0L (AEG) (1999) > Powertrain Management > Ignition System > Ignition Coil Pack > Component Information > Testing and Inspection > With Manufacturer's Scan Tool > Page 4772

A faulty camshaft position sensor can cause a random misfire. They usually fail due to physical damage, so inspect it see if it looks OK. It is located behind the camshaft timing belt pulley so you may need to remove the upper cover to see it.

Volkswagen Workshop Manuals > Golf L4-2.0L (AEG) (1999) > Powertrain Management > Ignition System > Camshaft Position Sensor > Component Information > Testing and Inspection > Page 4764
It has been my experience with both my 2.0's that neither runs well with non-OEM plugs. I have tried so many other plugs it was futile. So I would recommend that you put NGK's in it. Also use plug wires that have the metal connector housing.

Here is the Plugs, Wires and Coil DIY, it might be helpful.
Car now has NGK plugs and wires ( with the metal boot, sourced through NAPA, listed specific to AEG engine). I have reviewed my plug wire placement and connections too many times to count. The coil pack has the terminals labeled A,B,C,D. I have 1A, 2B, 3C, and 4D. In the link provided earlier to the Volkswagen service manual, the diagram of wire placement at the coil pack ( listed for the Golf 2.0 AEG, not sure it would matter) the wire placement showed wire 2 connected to left upper coil pack terminal, which is labeled C on my pack. I have even switched wires 2&3 to reflect this diagram, made no difference at all. It would seem most logical to me that since this problem arose only after the initial swap of plug wires, coil pack and O2 sensor that the problem must come from 1 of these areas. As stated earlier, I have checked resistance now on both new coil packs at ~ 7500 with the ambient temperature in the 30s F. I am by no means an ASE tech, but have been a mechanic my entire life (48 years) for myself, as well as the public. I again am at a loss. Any other suggestions? I thank you once again.
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I should be clear that even after putting the NGK plugs in, same symptoms, made no difference
Plugs 2 and 3 are attached to opposite ends of the same coil and thus always fire together. Interchanging the wires should have no effect as you say. The same goes for 1 and 4.

My Bentley manual does show 2 and 3 connected opposite from the linked page, but should make no difference.

You seem to have eliminated all the things that have been changed since it last ran OK, so I was starting to suggest other common things that could cause your symptoms like the cam position sensor. One last thing, ugly as it might be, is to put the old coil back in just to eliminate that for good.
Also should mention that I just swapped the coil pack for the original cracked vw one, made no difference at all
So, was the O2 sensor an OEM replacement, or a universal type that required wire attachment?
O2 sensor is Bosch. Not universal wire in type. The problem was solved by replacing one plug wire for one of the old originals. Bad wire out of the box (NGK COPPER). Thanks to everyone for all the help. It is greatly appreciated.
O2 sensor is Bosch. Not universal wire in type. The problem was solved by replacing one plug wire for one of the old originals. Bad wire out of the box (NGK COPPER). Thanks to everyone for all the help. It is greatly appreciated.
Interesting. We just replaced our wires a bit ago with the recommended NGK types. Kinda surprised to see NGK have a bad wire out of the box. Guess no one is immune to issues.


(PS: Glad you got it sorted out!!)
Interesting that the plug cable was bad even though the resistance measured good.

Glad you got it sorted out!
Woo hoo!!! :party
You had me over here sweating bullets for a while..

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