2000 Other Volkswagen Models Code PO102 + Rough running engi

Thanks for sticking with me on this KHlow.

I decided to check the codes again today before doing anything. I idled the car and tested the car at 2000 rpms... the rough running still persists at 2000 RPM (engine shakes, bogs down, wants to stall). Checked the codes and did not get a PO134 code immediately. Instead, I got a PO301 error (misfire cylinder 1). I let the car cool down. Came back and checked the codes and the PO301 was the only one there. I cleared the code and cranked the car and let it idle. I pushed the idle up to 2000 rpms and the shaking was still there. I got a PO301 again... cylinder 1. I decided to check the plug wire for #1. Popped off the end, did a visual, and then plugged it back on.

Interestingly, the car idled perfectly up to about 3500 rpms after I did this. I decided to drive it. I took it up to about 3000 rpms on a couple of stop and gos... and everything seemed fine. I thought... the darn plug wire wasn't on tight. But then, on my way back to my house, the rough running happened again, only this time it seemed to happen at a lower rpm... about 1500.

Got back to the house... checked the codes and got a PO301 error again. So, I decided to let the car cool and then I changed the #1 spark plug. The old one was fouled. I thought... AHA! But, no, after I cranked it, I got a PO302 code (Cylinder 2). What the???? It migrated to cyl 2? I let the car run for a bit, and it ran rough at almost any speed now. I checked the codes after a few minutes and got these codes....

PO300 (Multiple mis-fires detected)
PO301 (cyl 1)
PO302 (cyl 2)

Later, the PO134 code came back into the picture.

So, now I am a bit frustrated. I corrected the original problem with the MAF sensor (Code PO102) and that code has not come back. But since then, I have multiple misfires.

In light of this new info, I decided to change out the remaining 3 spark plugs tomorrow. Do you think that this new info still indicates a bad 02 sensor like the code says, or does this sound electrical in nature? For the record, I replaced the coil on this monster of an automobile back in April. These 2000 Cabrios seem to have a problem with the coils and the aftermarket coils are not all that dependable.

I appreciate any advice you can give me on this. I'm considering buying plug wires. Could it be the distributor cap? I guess what I'm saying is, maybe I should replace the plug wires and dist. cap tomorrow along with the spark plugs. Of course, if it is likely that the O2 sensor would create multiple mis-fires and the other symptoms I have described, then maybe I should replace the 02 sensor first.

What do you think?

As for the EGR valve... where would it be according to this diagram. VW doesn't use the EGR terminology...

The spark plug was sooty. It was coated and in a black residue. Carbon I assume. I also assume that is from a too "lean" condition.

I replaced the remaining 3 plugs and they were all black, but not as dirty as plug #1. The car continues to run rough and at low idles now. I checked codes and got 3 misfires.

PO300 Multiple misfires
PO302
PO304

So, I have received misfire codes on cylinders 1, 2 and 4 at different times.

Before I changed plugs
Misfire on Cylinders 1 and 2

After I changed plug 1
Misfire on cylinder 1 and 2

After I changed plugs 2, 3 and 4
Misfire on cylinder 2 and 4

I did check the plug gap, and these Bosch Platinum Plus plugs require a.040 not adjustable gap. There is one thing. Each plug came with an extra top piece. The metal prong that the plug wire connects to. They are different sizes, the one which came installed on the plug and the one which was the extra. The extra one is longer. I am going to wait until the car cools and remove the plugs and change the metal piece. I believe the one that is installed may be shorter than the ones on the plugs which I took out. I didn't think to check before I installed the new plugs. I'll wait until the car cools and will update when I have completed the change.

The plug tips were fine. They were the same size as the old plugs. No problem there.

I have decided to replace the plug wires just on a hunch that their doesn't seem to be enough fire coming through. The plug wires look old and dried out and somewhat brittle. These are just hunches of course. If not the plug wires, I will replace the distributor cap also. If it is not the plug wires and dist cap, then I suspect I might have a bad coil. Another bad coil. This model vw has a problem with coils according to one mechanic I spoke to.

I have ordered the plug wires online and it will be a few days before they get here. Will update this thread after they are installed.