99 VW Golf MK4 2.0L 8V - Running Too Rich/No Power

Status
Not open for further replies.
M

Mr_Accord

Joined
Jan 24, 2007
Messages
450
Location
LBP
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 the of 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.
 
Last edited:
It's a shame that you can't post technical data on this forum without it being censored.

Good Luck with your car.
 
Last edited:
Coolant temp sensor and MAF would be the first things to check.

How recent are the plugs? Distributor or COP? o2? Cat?

Edit*
I just watched the video, if the manifold is leaking excess air gets in, makes the 02 see a lean condition and riches up to compensate. The precat 02 sees rich and you get a code, and eventually the cat dies.

Patch it up an you'll be golden
smile.gif
 
Last edited:
Originally Posted By: Olas
Coolant temp sensor and MAF would be the first things to check.

How recent are the plugs? Distributor or COP? o2? Cat?

Plugs (NGK G-Power), wires, and coil pack were replaced about 3 yrs ago. They don't have more than 40K km on them.
 
It sounds like the cat may have broken up. Common enough with VW.
Hit it with a mallet, don't be surprised if it rattles.

Edit: If it did the resonator and muffler is full of cat pieces. Worth checking.
 
Last edited:
cilinder 4 misfire detected. can you swap ignition coils between cilinders, or have you checked the spark plugs?

likely you have a leaking injector on cilinder 4, which would cause the P0172 error aswell. check the spark plugs for discoloration.
 
Originally Posted By: Jetronic
cilinder 4 misfire detected. can you swap ignition coils between cilinders, or have you checked the spark plugs?

likely you have a leaking injector on cilinder 4, which would cause the P0172 error aswell. check the spark plugs for discoloration.

There was a run of defective ignition coils plaguing VW and Audi about this time.
 
Originally Posted By: FowVay
It's a shame that you can't post technical data on this forum without it being censored.

Good Luck with your car.


...what are you talking about?
 
Originally Posted By: Mr_Accord
MAF sensor was replaced with an used OEM one back in november.


Clean the MAF with MAF cleaner for posterity

If you've got good spark at all cylinders
Yet #4 plug is coming out sooty and wet?
If compression is there and good (should be), then I'm in the camp of stuck injector.
 
Originally Posted By: Jetronic
cilinder 4 misfire detected. can you swap ignition coils between cilinders, or have you checked the spark plugs?

likely you have a leaking injector on cilinder 4, which would cause the P0172 error aswell. check the spark plugs for discoloration.



This car has a single coil pack with 4 ignition wires, and the pack is after market so its not the original that used to cause problems.
 
Originally Posted By: michaelluscher
Originally Posted By: Mr_Accord
MAF sensor was replaced with an used OEM one back in november.


Clean the MAF with MAF cleaner for posterity



As stated in my post the MAF was already cleaned.
 
Originally Posted By: Mr_Accord
Originally Posted By: Jetronic
cilinder 4 misfire detected. can you swap ignition coils between cilinders, or have you checked the spark plugs?

likely you have a leaking injector on cilinder 4, which would cause the P0172 error aswell. check the spark plugs for discoloration.



This car has a single coil pack with 4 ignition wires, and the pack is after market so its not the original that used to cause problems.

A bad coil pack on this engine would mostly likely effect 2 cylinders.
It could be sticking injector but these Bosch units are pretty trouble free. I have a few extras here if you need one.

Just rap the cat with a mallet if you would just to satisfy my curiosity. This was real common on AEG engines.
 
Last edited:
but a wrecked cat wouldn't just affect cilinder 4. you'd get the same issues on multiple cylinders. That's what I'd expect anyway.

or there's a compression issue on cylinder 4.

check the plugs, if cylinder 4 actually has a problem thios will show up. swap the plug and lead (if possible) with another cilinder to determine if the problem is with either.

if the plugs state is consistent with running rich (lots of soot) check the injector (you can swap them to another cylinder again) or do a compression test.
 
Chances are it is not the cat but on the AEG its the first thing i check when a misfire code is detected.
I have a pile full of them, all broken media.
 
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:

29276h5.jpg


Look pretty burnt, they didn't have any gas or oil residue on them. Going to change anyway.
 
Status
Not open for further replies.

Similar threads

Redhawk454
After 1,800 miles my motor oil is black (gasoline engine)
2
Replies
22
Views
4K
DHBWA
E
What would cause inconsistent oil consumption?
2
Replies
34
Views
3K
ripcord
A
Timing chain rattle Audi A7 3.0tdi
Replies
8
Views
2K
vinu_neuro
Cujet
DC arc welder restores sulfated golf cart batteries.
Replies
8
Views
1K
Cujet
TiGeo
Oil, coolant, trans, intake air temp data log from track session
Replies
9
Views
979
TiGeo
Back
Top