No power off idle,,, Emissions Workshop

Yesterday my 04 Passat strated having an issue. There was no indication that anything was going wrong before hand.

Drove the car to dinner, when finished the car started fine, I backed out of the parking spot, selected drive and then when trying to accelerate it was like I wasn't even pressing the pedal. Kept pressing, the rpm's came up slow and when it hit 1700, the engine seemed nomal. Then the Emissions Workshop and CEL lit up. Drove a couple blocks thinking about it and had a similar issue a couple winters ago when the snow screen got clogged with snow. So I pulled into a parking lot, pulled snorkel and the airbox cover. Snowscreen was clogged with some sort of debris. Cleaned it out and all seemed fine except the EW and CEL were still on.

Drove home and the next morning it started fine but I still got the EW and CEL. Backed out of the garage, went to drive forward and same thing. No accellration until it hits around 1700 rpm. Once you get above 1700, the engine runs normal,, accelration and even pulling hard uphill. Drove it to work and parked it.

Anything obvious to look for??? I haven't found a local with VagCom.

Look inside the entire intake piping circuit in front of the snow screen. I had limp mode issues similar to yours. Code 16683 - "Boost Pressure Regulation: Control Range Not Reached" (no Emissions Workshop light, though). I had been scratching my head for a while and discussing the problem with Jeff @ Rocketchip (I've got RC2 and this only started after the chipping).

Well, I had a headlight go out and I popped off the connector pipe between the intake plenum and the snow screen to get to the bulb. There was a little debris in the screen, but a couple of dead bugs fell out of the connector pipe. When I looked inside the connector pipe, there was a leaf wedged in there in such a way that it could flap around and block 60-70% of the area. I cleaned everything out and haven't had a problem since.

Best to find someone in your area with VCDS, though.

Hmmm,,,

after I had cleaned the snowscreen out I drove home without the whole snorkel. Yesterday morning I put it back on before I drove it to work.

I'll look everything over tomorrow but I'm suspecting something more invovled. Today I was going to pull it into the shop and start trying to check it over. When I started it, everything almost seemed normal except the WE and CEL light came on. After idleing a couple seconds it started missing and quit. Tried starting it a couple times and same thing except lots of smoke from the exhaust. Now it won't start at all.

Well, I haven't had time to deal with this so I had a neighborhood guy look at it. He's a diesel mechanic, but as far as VW's has really only worked on the older stuff mostly. OBD codes show EGR error and MAF. So he unplugged the EGR and cleared the codes. He says it runs fine but feels it has too much turbo lag. Thus he feels the intake may be plugged up also. The MAF didn't come back and thinks that may have been triggered because of the debris that was partially plugging the snow screen.

He's going to see if he can revive the EGR and if not just get rid of it like quite a few people do. My concern is will the car pass inspection in New York State with the CEL on?

Boatman said:

Well, I haven't had time to deal with this so I had a neighborhood guy look at it. He's a diesel mechanic, but as far as VW's has really only worked on the older stuff mostly. OBD codes show EGR error and MAF. So he unplugged the EGR and cleared the codes. He says it runs fine but feels it has too much turbo lag. Thus he feels the intake may be plugged up also. The MAF didn't come back and thinks that may have been triggered because of the debris that was partially plugging the snow screen.

He's going to see if he can revive the EGR and if not just get rid of it like quite a few people do. My concern is will the car pass inspection in New York State with the CEL on?

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Clogged intakes on these Passat's are not common. It takes a few minutes to remove the EGR valve and inspect the manifold for clogging. Sounds like you don't have a VCDS to do a real scan. My guess is a split hose of a vacuum line issue. These MAF's seem to last pretty well also.

I don't know about passing smog in NY with a CEL on, but I'll bet it will be an issue for them.

He pulled the EGR and found the manifold substancially blocked. When he removed the manifold the intake ports were down to the size of a dime so I'm thinking it was everything coming together at the same time. Like I said, unplugging the EGR the engine ran fine except for the lag and I assume this was due to the blockage.

A called the place that does my inspections and in NYS the diesels are exempt from being connected to the DMV computer. He said as long as I tell him there is no EGR ahead of time he doesn't think the CEL will be a problem. He'll pull the code with a scanner and as long as the EGR is the only code he'll "pass" it.

I'm kind of surprised that I didn't notice a significant drop in fuel mileage.

So after having the intake cleaned and driving the car for a couple hundred miles,,, everything seems to be back to normal. The engine is a bit snappier and gets up to speed quicker so I guess my issue is solved.

Had one with 02 codes and maf codes that was behaving that way a few weeks ago. EGR valve was sticking due to carbon caked on it.

Tell-tale sign was black smoke (unburned fuel) coming out while the lack of power happened. Logic is if there is unburned fuel then there must be lack of oxygen to burn the fuel. EGR gas displaces the oxygen.

Matter of fact I got two BRM's here right now doing something similar that I think is sticking EGR.