00 Jetta VR6 common problem!!

[CaseyVR6]

Ok, I know of 5 people now who have an identical problem and have all tried the same things. We all have a Jetta IV VR6 ranging from my 2000 to a 2003. All are MT. Problem 1 is this:

The check engine light comes on and the car is acting very odd. It will run fine at times, and other times it bucks or hessitates then shoots off especially when first accelerating like when a light turns green. While driving, even at freeway speeds, the car will hickup like the worst clogged injectors you can imagine. If you really get on the gas, particularly on wet or snowy roads, the dashboard lights up like a christmas tree with the traction light, epc light, and check engine light... and then the car has probably 20% - 25% of it's power making it difficult to accelerate past 45mph on straight flat ground. If you turn the car off and on again, the lights are out and full power is restored. I have notices a slight loss of fuel efficiency, but I wouldn't notice if I weren't looking at everything. The engine code is emissions pre-cat zone 1, which is typically mass-air. So far, myself and the other 5 fellas have tried to fix with the following parts with no resolve; mass air, coil, plug wires, o2 sensors, plugs, fuel filter, clean or replace air filter. The only things I'm thinking are left are the cat and the ECM. Help, please?

The second problem, more annoying than anything, is the flickering of the lights. Usually at idle, sometimes at highway speed, the lights seem to shutter a little. Just get slightly dimmer and slightly brighter, as you would expect to see just before a car was about to stall. I'd say they dim and brighten 2 or 3 times a second while at idle, and until you rev the engine at highway speeds. Keep in mind all the above parts that have already been replaced.

Thanks for the help!!!

[boschmann]

http://www.volksparts.com/recalls.htm

[CaseyVR6]

I have a 2000 VW Jetta and the recall is for '01 - '30, and as you can see in the original post the coil has already been replaced. Thanks for the link, but it's not much help.

[bahnfire]

You might want to check the air screen in the air box below the air filter. During hard acceleration, a clogged air screen can result in a check engine light. That was the case in my 99 VR6. Mileage and pickup increased significantly after the fix.

[veedubmechanic]

Have you replaced ALL those things on YOUR car or all those parts here and there on other cars.

Have you replaced The ect yet? If its not green then replace it.

Have you checked all the vacuum lines if they crack then you can get check lights for system too lean.

Have you tried doing a induction service? cleans the injectors and valves

How many miles? The ecm isnt bad, unless you chipped it.

[CaseyVR6]

On my car, I have replaced the 02 sensors, plugs and wires, mass air, "recharged" my air filters, and replaced the fuel filter a few months ago. The coil pack was replaced about a year ago. I'm a bit confused about replacing the ect, to be fully honest I'm not sure what it does or how often it should be replaced. The vacume lines are all fine, flexible, and free of cracks. The hose still looks and feels as it should. I have not tried an induction service, I didn't want to put out that kind of money. The car has 180,300 miles on it, and the only reason I would consider replacing the ecm is because a buddy with a BMW had VERY similar symptoms and replaced all the same parts in basically the same order, and it turned out that the ecm had "gone bad"... as rediculous as that sounds.

This has been a very frustrating problem for about 2 months now, so believe me when I say ANY help is appreciated. Even if it's not a direct lead to fixing this machine I love.

"If it has tits or wheels, it will cause you trouble"

[boschmann]

What check engine codes do you get?

[veedubmechanic]

If the ECT is bad it can cause your temp guage to fluctuate or take a long time to come off 0. IF the ect is not GREEN then replace it. Its right under the small engine cover on the front by the battery. Its on the bracket for the thermostat.

A new ecm is arround $1000. I have only seen 2 ecm replaced before and one was on an 96 gti vr6 and the other on on a touareg.

All cats do go bad, and i am suprised the cat hasnt been replaced on your cat with 180k miles.

[CaseyVR6]

ECM is still green, so we're safe there. I have a huge suspicion you're right and it's going to be the cat. Bottom line is I'm going to have to pony up the cash and have the dealership go over it with the computer... then take it someplace that isn't going to totally blast me with the install. Thanks for the help, I truly appreciate it. I'm definatley hooked into the community... and to think I was gonna sell my sexy ride!!

[boschmann]

You don't have to go to the dealer to get the codes read. Most chains like Advance Auto Parts & & Autozone will read them for free. They may only have a generic scanner, but in most cases it's sufficient to point you in the right direction.

[veedubmechanic]

Theres an easy way to chek the cat manually...
Warm up the engine to normal operating temp.
Check the temp of the cat before and after the cat with a temp gun. If the temp is more than 100deg F different then the cat is bad. (on a vr6 check it at the front o2 sensor and ad the rear o2 sensor)

Oh and if you DO replace the cat- spend the 1300 for a vw cat because I have seen many aftermarket ones not fit right and also ones that arent made to VW specs and the check light keeps coming back on.

[CaseyVR6]

Fantastic advice, I'll definately give that a shot. Yeah, I almost exclusively buy VW parts. Best thing ever is 1-800-vw-parts. They've got vw parts, the real ones, for WAY less than dealership cost. The cat through them will be $387, and the dealership wants $1200. Gee, wonder who I'll buy from considering it's truly the same parts. I HIGHLY reccomend you call them next time you need a part. They have saved my broke pocket more times than I care to remember. Seriously though, that cat trick sounds too good to be true but I'll give it a go. Thanks again

[boschmann]

Just a note on checking for cat efficiency with an infrared temp gun. You want to compare the temp readings of the oulet to the inlet with the engine at operating temp & you should keep the engine revved slightly. On an older 2-way cat (approx. <'96) the outlet temp should be about 100F higher than the inlet temp if it's working properly. On a newer 3-way cat the outlet should be about 30F hotter.

[CaseyVR6]

I just found this old post. I wanted to add that it was the cat. After replacing the cat (and a brand new set of o2 sensors since it felt like the right thing to do) that problem is all gone.

[ctuagent117]

you also could of used a magnaflow cat there great on vws and are the ONLY cats that perform better than stock. slightly better not much but its there. VW has excellent cats. the magna floe is cheaper than 360 and works as well or better. glad your vws back in shape