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I have a 1999.5 MK4 Golf with the 2.0L 8v AEG engine. This is my winter beater car that I drive about 20 mins everyday to and from work. About a month ago the check engine started intermittently coming on during my commutes. I would drive in the morning with it on and when I drove home in the evening it wouldn’t show up, all the while the engine was running fine, nice a peppy. I kept a code scanner in the toolbox of my trunk and every time I checked it. It was a P0172 – Engine Running too Rich (BANK1). I did a quick check of the MAF and TB which were cleaned in the fall (but I cleaned them again), The air filter is new, and I looked to see if there were any leaking vacuum lines…none that I saw. I didn’t have time to look at when it this problem came up… time/bad winter weather. I was planning on dealing with it this weekend when…
Today however on the way home from work the car was running terribly. I had my foot to the floor and it was barely going anywhere, and the check engine light was flashing a cylinder 4 misfire. I managed to get it home, but it idles badly and when i give it a good rev it stalls now. One day its running alight, today can barely keep it going. I made a YT video.
[video:youtube]https://www.youtube.com/watch?v=VyerND3CzRA[/video]
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This may be pointless, but I was working as a VW parts guy when your car was new and I remember the AEG. I sold piles upon piles of MAFs, front o2 sensors, and coolant temp sensors to AEG engines specifically. Failures of these kind of parts can cause a P0172. I was just a parts guy at the time and I didn’t know what problems the techs were fixing, but warranty was having a conniption fit over the cost.
VW solved that warranty money hemorrhage like a boss, though.
(List Prices)
The MAF went from $375 down to $49
The o2 went from $140 to $22
The CTS went from $24 to $3Thanks. Yeah i’m well aware of the sensors these cars go through. Its already on its 3rd coolant temp sensor which was changed a few months ago. The MAF is a used OEM one which was changed in the fall. If it was the o2 sensor wouldn’t you think the code specific to that fault would come up though instead of the P0172 code?
all right, so its been awhile but I finally got around to taking a look at the car. Funny thing is I pulled the battery cables awhile it sat and put it on a charger since it was going to be really cold the whole week. Hooked it up again today and the car runs great…starts fine,I can rev it and it doesn’t stall, and there are no check engine codes???
I decided to check the plugs anyway. So I pulled all of them and this is what they look like:
[IMG]http://i60.tinypic.com/29276h5.jpg[/IMG]
Look pretty burnt, they didn’t have any gas or oil residue on them. Going to change anyway.
So changed my plugs and replaced the vacuum line between the manifold and fuel pressure regulator. Thought it was fixed but…Yup too good to be true. After a few days my CEL came back with the same P1702 Bank1 running rich code. Engine still has a good rev and power, but the exhaust smells heavy again. So its only a matter of time before these plugs get burned. Going to go back to vacuum line checking. Got a hold of my buddies VCDS, but its the shareware version with the chinese knock off plugs that works occasionally. Haven’t been able to get it to function to get a fuel trim status.
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