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View Full Version : VR6 idling rough.. feels like its running on 5 cyl, help please


tictactoe2004
10-08-2007, 10:20 PM
Ok.. so i'm used to working on my mustang lol and this is the first issue i've ever had with this car.. so here's whats going on, any suggestions would be greatly appreciated.

2001 GTI VR6, 120,000KM

About a week ago my check engine light came on but it felt like it was running ok. Friday I went to start it and it felt like it was idling really rough, it felt like it was running on 5 cylinders. It's been a while since I had a tune up and I thought maybe one of my spark plugs was on its last leg so I went and bought a new air filter and spark plugs hoping one of my plugs was dead but it wasnt the problem.

I started trouble shooting, I disconnected one spark plug wire at a time.. they all made the car run a lot rougher except when I pulled cyl #1, that one made almost no difference. The car doesnt really have a coil, it has 3 banks of 2 wires on the drivers side of the motor, I found out that cyl 1 and 6 both fired at the same time so I switched those two wires, pulled cyl 6.. it ran way rougher so I put it back and pulled cyl 1 again and almost no difference again so I assume the problem isnt spark related. I put the wires back to how they should be and pulled the wire from the fuel injector on cyl #1 and it felt 90% the same.. didnt matter if the injector was plugged in or not, it idled and revved almost the exact same.

My buddy had a code reader, so we checked for codes and found the following two.

P0420 Catalyst System Low Efficiency
P0301 Cylinder 1 Misfire Detected

I'm assuming I got the 301 code because I had the car running for a couple seconds without the wire on cyl 1, but I also tried it on all 6 cyl's, so I dunno if it should have stored the codes on all 6 cyl's or just that one since it was the last one that was run with no wire.

I'm assuming that some how my cyl #1 fuel injector has died or some how got plugged up... is there something else I can check? Should I just go buy a new injector? I was thinking I can take the intake off and swap injectors #1 and #6 and see if the problem moves to cyl 6? It's not a huge job, but a fair bit of work to do that just to trouble shoot...

I'll also mention that over the last couple years when my engine was first started in moist weather 3 or 4 times it felt like it did the exact same thing or something really close? but it went away as soon as the engine warmed up... only problem is that sounds like more of an electrical thing to me, not fuel?

anyways as you can probably tell i'm fairly noob with this shit and could use any suggestions or pointers you guys have..

Thanks.
slowep3
10-08-2007, 10:26 PM
ever changed ur fuel filter?
tictactoe2004
10-08-2007, 10:31 PM
Originally posted by slowep3
ever changed ur fuel filter?

No, I have not... Would that effect one cyl this way? or are you thinking maybe something got past the filter and went into injector one and plugged it up, since its the first injector on the rail?
Annoyingrob
10-08-2007, 10:33 PM
Pull the spark plug out of #1, and see that it looks like.

You're probably right about the injector being stuck. It's probably stuck OPEN though, dumping fuel into your exhaust, which is why you're getting catalyst problems. If you pull the #1, and it's soaked with fuel, that's probably your problem. You may be able to just send your 6 injectors off for cleaning and flow testing.
tictactoe2004
10-08-2007, 10:38 PM
Originally posted by Annoyingrob
Pull the spark plug out of #1, and see that it looks like.

You're probably right about the injector being stuck. It's probably stuck OPEN though, dumping fuel into your exhaust, which is why you're getting catalyst problems. If you pull the #1, and it's soaked with fuel, that's probably your problem. You may be able to just send your 6 injectors off for cleaning and flow testing.

I did smell a bit of fuel and there was some moisture coming out of my exhaust... all the plugs are brand new so it looks ok, but i'll check to see if its soaked with fuel in the morning.
tictactoe2004
10-08-2007, 10:41 PM
if its the injectors, is there someone in the city that cleans and flow tests injectors? or any good recommendations?
Annoyingrob
10-08-2007, 10:42 PM
Originally posted by tictactoe2004


I did smell a bit of fuel and there was some moisture coming out of my exhaust... all the plugs are brand new so it looks ok, but i'll check to see if its soaked with fuel in the morning.
Moisture is normal. Fuel smell can either be too much fuel, or just non-ignition.

Try running the car with the #1 plug out, sitting on the block, plugged into the wire. You can see if it sparks. This will tell you if you are infact getting a spark to #1.
tictactoe2004
10-08-2007, 10:53 PM
Originally posted by Annoyingrob

Moisture is normal. Fuel smell can either be too much fuel, or just non-ignition.

Try running the car with the #1 plug out, sitting on the block, plugged into the wire. You can see if it sparks. This will tell you if you are infact getting a spark to #1.

k, added that to the list to try in the morning.
Akagi Redsuns
10-09-2007, 01:45 PM
Perhaps it's the VW famous coil-pack issue?

http://forums.vwvortex.com/zerothread?id=1568254
Supa Dexta
10-09-2007, 01:49 PM
Is it coil on plug? either way, remove them one at a time and you may be able to pin point which one is giving you trouble, if at all.. It will get worse (shake studder) when you take off the good ones, and if there is a bad, plug/injector/coil/wire it won't be any different when you get to that one...
littledan
10-09-2007, 02:03 PM
does it only occur at some times and not others? a buddy of mine had a vr6 with similar symptoms and turned out it was the timing chain becoming loose. we found this out when the motor puked out a rod on the highway.
Annoyingrob
10-09-2007, 02:05 PM
It's not coil on plug. It's a waste spark system with 3 coils each firing 2 cylinders. As was discussed above, he tried swapping cylinders 1 and 6 around with no change. If it WAS a bad pack, it would be running on 4 cylinders, not 5.
tictactoe2004
10-09-2007, 10:31 PM
Originally posted by littledan
does it only occur at some times and not others? a buddy of mine had a vr6 with similar symptoms and turned out it was the timing chain becoming loose. we found this out when the motor puked out a rod on the highway.

Well, I tried adding some fuel system cleaner and going for a spin... (hoping for an easy out)... anyways, not so much. From what I see cyl #1 is getting no fuel anymore, after going for a spin I let the car idle in my garage, it was 100% running on 5 cyl. I pulled the plug from cyl #1 out and it made absolutly no difference, none at all.. The spark plug is firing for sure, there's just no fuel in the cyl. From what I found out from talking to people and reading online, the electrical system that is connected to the fuel injector is similar to the coil in that two cyl's get fuel shot into them at once time so if it was an electrical problem to the fuel injector it would be happening to two cylinders.

I guess i'm going to pull it out tomorrow, god what a tight squeeze, I have to pull the front end to a service mode and remove the upper intake manifold in order to get to the injectors. I'm planning on buying a used one and installing it. Gonna drive it for a couple weeks and then do a major tune up which will include sending the injectors to RCTS for a full cleaning and testing. Fuck this thing is a lot tighter than my mustang :( heheheh oh well, it's 10x the car :)

Thanks for all the help guys.
Ashers
10-09-2007, 11:28 PM
Originally posted by tictactoe2004


...From what I found out from talking to people and reading online, the electrical system that is connected to the fuel injector is similar to the coil in that two cyl's get fuel shot into them at once time so if it was an electrical problem to the fuel injector it would be happening to two cylinders...



I thought that the VR6 from that year was Sequential injection... not batch fire?
tictactoe2004
10-09-2007, 11:38 PM
Originally posted by Ashers


I thought that the VR6 from that year was Sequential injection... not batch fire?

I could be wrong, but I would assume since two plugs fire at once that they would both need fuel at the same time.
Supa Dexta
10-10-2007, 07:34 AM
I don't know this engine at all, but I do know there are engines out there that will fire on the exhaust stroke as well..
tictactoe2004
10-10-2007, 08:53 AM
well, bad news... after tinkering with it a little more I discovered that there was fuel on the spark plug on cyl #1. Talked to George at Tunedub and he's seen this before where the one of the cylinders died and it needed a head rebuild. Boo fucking hoo.. i'm going to take it in to him and get him to check it out before I start ripping more shit apart.
Annoyingrob
10-11-2007, 07:27 PM
do a compression test now.