2003 Jetta 1.8T misfires, dead oxygen sensor

My daughter just had her 53,000 mile 2003 1.8T Jetta repaired (for a
number of issues). They said there were codes for misfires in all four
cylinders and that the oxygen sensor needed to be replaced (I assume it
was the front one). The car has had an issue with trying to stall for
maybe 30-60 seconds after startup.

If the oxygen sensor was bad, I'm guessing that it was killed by
something upstream like whatever is causing the misfires.

Anybody got an idea for "most likely" causes of misfires and startup
stalling issues in the 1.8T? I'm thinking coils or MAF sensor.

By the way, this is not a dealer service department, but it deals
primarily with German cars so the techs are probably fairly
knowledgeable. However, I suspect they are not as familiar with "most
likely" causes as dealer techs are. Unfortunately the local VW dealer
service department is predatory and untrustworthy.

Thanks,

Bill

On Mon, 09 Jun 2008 17:29:52 -0500, William Maslin
> wrote:

>My daughter just had her 53,000 mile 2003 1.8T Jetta repaired (for a
>number of issues). They said there were codes for misfires in all four
>cylinders and that the oxygen sensor needed to be replaced (I assume it
>was the front one). The car has had an issue with trying to stall for
>maybe 30-60 seconds after startup.
>
>If the oxygen sensor was bad, I'm guessing that it was killed by
>something upstream like whatever is causing the misfires.
>
>Anybody got an idea for "most likely" causes of misfires and startup
>stalling issues in the 1.8T? I'm thinking coils or MAF sensor.
>
>By the way, this is not a dealer service department, but it deals
>primarily with German cars so the techs are probably fairly
>knowledgeable. However, I suspect they are not as familiar with "most
>likely" causes as dealer techs are. Unfortunately the local VW dealer
>service department is predatory and untrustworthy.
>
>Thanks,
>
>Bill
Bad MAF is not going to cause misfires says this shade tree mechanic.
Temic seems to be a prefered coil. Beru least liked.

Bad coils is a rather well known issue with VWs I would have thought
most cars had been fixed by now.

http://www.theautochannel.com/news/2...04/154251.html
http://www.mylemon.com/VW_18T.php
http://forums.vwvortex.com/zerothread?id=1568254
http://www.gti-vr6.net/library/engin...oil_packs.html

Bad mas air flow sensors can absolutely cause misfires by causing the system
to run too lean. It is also likely to cause misfires on all 4 cylinders as
it affects all of them. MAF sensors are pretty common but not for this
issue. I have also seen faulty Coolant Temp sensors cause this issue.
Especially on cold startup first thing in the morning. What color is the
coolant temp sensor in her car??? If its the black sensor I would recommend
replacing it as they are well known to cause many problems & have been
changed to a newer green sensor.

I would also recommend checking all the vacuum/PCV hoses under the front of
the intake manifold as they are prone to oil contamination which causes them
to go soft & split. These cause air leaks which also can cause misfires on
all cylinders until they get bad enough to cause an adaptation code.

Considering you had misfire codes for all 4 cylinders you need to look at
something that affects all the cylinders rather than things like coils that
usually affect on single cylinders.

Hope this helps.

Craig



"Jim Behning" > wrote in message
news
> On Mon, 09 Jun 2008 17:29:52 -0500, William Maslin
> > wrote:
>
>>My daughter just had her 53,000 mile 2003 1.8T Jetta repaired (for a
>>number of issues). They said there were codes for misfires in all four
>>cylinders and that the oxygen sensor needed to be replaced (I assume it
>>was the front one). The car has had an issue with trying to stall for
>>maybe 30-60 seconds after startup.
>>
>>If the oxygen sensor was bad, I'm guessing that it was killed by
>>something upstream like whatever is causing the misfires.
>>
>>Anybody got an idea for "most likely" causes of misfires and startup
>>stalling issues in the 1.8T? I'm thinking coils or MAF sensor.
>>
>>By the way, this is not a dealer service department, but it deals
>>primarily with German cars so the techs are probably fairly
>>knowledgeable. However, I suspect they are not as familiar with "most
>>likely" causes as dealer techs are. Unfortunately the local VW dealer
>>service department is predatory and untrustworthy.
>>
>>Thanks,
>>
>>Bill
> Bad MAF is not going to cause misfires says this shade tree mechanic.
> Temic seems to be a prefered coil. Beru least liked.
>
> Bad coils is a rather well known issue with VWs I would have thought
> most cars had been fixed by now.
>
> http://www.theautochannel.com/news/2...04/154251.html
> http://www.mylemon.com/VW_18T.php
> http://forums.vwvortex.com/zerothread?id=1568254
> http://www.gti-vr6.net/library/engin...oil_packs.html

I agree with Craig.
Since you have the 1.8t (1.8-liter turbocharged) engine each spark plug
should have its own coil. Some of the newer engines will have coils that
might pop up off of the plugs creating a misfire. People have devised ways
to secure these coils from popping up.
The Coolant Temperature Sensor can create a rich mixture so that needs to be
checked out. It might not even throw a DTC either.
Someone needs to plug into the computer to see what is happening there.
Guessing can be very costly!!!
Other things could be visually checked such as the color and level of the
engine oil. The color of the spark plug electrodes. Any cracked or loose
vacuum hoses/connections...........etc.

IF the CTS is bad and has not been changed then it could cause the 02 sensor
to go out again! 8^)
Also using the correct spark plugs will help the performance of this
turbocharged engine. BOSCH Plats are NOT the ones, but this is JMHO. I
think the preferred ones for performance will have 3 side electrodes.
--
later,
dave
(One out of many daves)

"Craig" > wrote in message
...
> Bad mas air flow sensors can absolutely cause misfires by causing the
> system to run too lean. It is also likely to cause misfires on all 4
> cylinders as it affects all of them. MAF sensors are pretty common but not
> for this issue. I have also seen faulty Coolant Temp sensors cause this
> issue. Especially on cold startup first thing in the morning. What color
> is the coolant temp sensor in her car??? If its the black sensor I would
> recommend replacing it as they are well known to cause many problems &
> have been changed to a newer green sensor.
>
> I would also recommend checking all the vacuum/PCV hoses under the front
> of the intake manifold as they are prone to oil contamination which causes
> them to go soft & split. These cause air leaks which also can cause
> misfires on all cylinders until they get bad enough to cause an adaptation
> code.
>
> Considering you had misfire codes for all 4 cylinders you need to look at
> something that affects all the cylinders rather than things like coils
> that usually affect on single cylinders.
>
> Hope this helps.
>
> Craig
>
>
>
> "Jim Behning" > wrote in
> message news
>> On Mon, 09 Jun 2008 17:29:52 -0500, William Maslin
>> > wrote:
>>
>>>My daughter just had her 53,000 mile 2003 1.8T Jetta repaired (for a
>>>number of issues). They said there were codes for misfires in all four
>>>cylinders and that the oxygen sensor needed to be replaced (I assume it
>>>was the front one). The car has had an issue with trying to stall for
>>>maybe 30-60 seconds after startup.
>>>
>>>If the oxygen sensor was bad, I'm guessing that it was killed by
>>>something upstream like whatever is causing the misfires.
>>>
>>>Anybody got an idea for "most likely" causes of misfires and startup
>>>stalling issues in the 1.8T? I'm thinking coils or MAF sensor.
>>>
>>>By the way, this is not a dealer service department, but it deals
>>>primarily with German cars so the techs are probably fairly
>>>knowledgeable. However, I suspect they are not as familiar with "most
>>>likely" causes as dealer techs are. Unfortunately the local VW dealer
>>>service department is predatory and untrustworthy.
>>>
>>>Thanks,
>>>
>>>Bill
>> Bad MAF is not going to cause misfires says this shade tree mechanic.
>> Temic seems to be a prefered coil. Beru least liked.
>>
>> Bad coils is a rather well known issue with VWs I would have thought
>> most cars had been fixed by now.
>>
>> http://www.theautochannel.com/news/2...04/154251.html
>> http://www.mylemon.com/VW_18T.php
>> http://forums.vwvortex.com/zerothread?id=1568254
>> http://www.gti-vr6.net/library/engin...oil_packs.html
>

VW had a flash for the ECU for misfire faults. The only way to know if the
engine gets it requires a visit to the dealer to check the software version.
VW should pay for the flash if there are misfire faults stored. So the next
time the MIL light comes on and the engine is misssing vist your deaaaaaaler
before the MIL turns off.

If I remember correctly that software flash was a TSB & not a recall so if
the car is out of warranty it won't be covered.


"Lost In Space/Woodchuck" > wrote in message
. ..
> VW had a flash for the ECU for misfire faults. The only way to know if the
> engine gets it requires a visit to the dealer to check the software
> version. VW should pay for the flash if there are misfire faults stored.
> So the next time the MIL light comes on and the engine is misssing vist
> your deaaaaaaler before the MIL turns off.
>

In rec.autos.makers.vw.watercooled, William Maslin wrote:

>
>Anybody got an idea for "most likely" causes of misfires and startup
>stalling issues in the 1.8T? I'm thinking coils or MAF sensor.

All of the other posts offer good info. In addition, I would look at
the engine in the *dark* as it is running and look for arcing on
wires or coil. It is an easy cheap diagnosis method, tho it may be
hard to find good darkness this time of year.

If the misfiring is not occurring as you check, you could try
creating a light mist of water to encourage potential arcing.

So I am not saying arcing is the probable cause. I am saying it is
fairly simple to look for.

TSB yes, but misfire faults are related to the emission warranty. And since
the ECU is covered for 8yr/80,000 miles so is the flash.


"Craig" > wrote in message
...
> If I remember correctly that software flash was a TSB & not a recall so if
> the car is out of warranty it won't be covered.
>
>
> "Lost In Space/Woodchuck" > wrote in message
> . ..
>> VW had a flash for the ECU for misfire faults. The only way to know if
>> the engine gets it requires a visit to the dealer to check the software
>> version. VW should pay for the flash if there are misfire faults stored.
>> So the next time the MIL light comes on and the engine is misssing vist
>> your deaaaaaaler before the MIL turns off.
>>
>

coil over plug coils, thus can't see secondary voltage.

"Tom's VR6" > wrote in message
...
> In rec.autos.makers.vw.watercooled, William Maslin wrote:
>
>>
>>Anybody got an idea for "most likely" causes of misfires and startup
>>stalling issues in the 1.8T? I'm thinking coils or MAF sensor.
>
> All of the other posts offer good info. In addition, I would look at
> the engine in the *dark* as it is running and look for arcing on
> wires or coil. It is an easy cheap diagnosis method, tho it may be
> hard to find good darkness this time of year.
>
> If the misfiring is not occurring as you check, you could try
> creating a light mist of water to encourage potential arcing.
>
> So I am not saying arcing is the probable cause. I am saying it is
> fairly simple to look for.

In article >,
Jim Behning > wrote:

> On Mon, 09 Jun 2008 17:29:52 -0500, William Maslin
> > wrote:
>
> >My daughter just had her 53,000 mile 2003 1.8T Jetta repaired (for a
> >number of issues). They said there were codes for misfires in all four
> >cylinders and that the oxygen sensor needed to be replaced (I assume it
> >was the front one). The car has had an issue with trying to stall for
> >maybe 30-60 seconds after startup.
> >
> >If the oxygen sensor was bad, I'm guessing that it was killed by
> >something upstream like whatever is causing the misfires.
> >
> >Anybody got an idea for "most likely" causes of misfires and startup
> >stalling issues in the 1.8T? I'm thinking coils or MAF sensor.
> >
> >By the way, this is not a dealer service department, but it deals
> >primarily with German cars so the techs are probably fairly
> >knowledgeable. However, I suspect they are not as familiar with "most
> >likely" causes as dealer techs are. Unfortunately the local VW dealer
> >service department is predatory and untrustworthy.
> >
> >Thanks,
> >
> >Bill
> Bad MAF is not going to cause misfires says this shade tree mechanic.
> Temic seems to be a prefered coil. Beru least liked.
>
> Bad coils is a rather well known issue with VWs I would have thought
> most cars had been fixed by now.

You are correct. However, even the improved coils seem to be
troublesome. For example, our 2002 Passat had all four coils replaced
back in 2002 or 2003 when the big coil disaster occurred. However, it
later developed (around 55K miles) subtle misfire problems which
Woodchuck correctly diagnosed as two bad coils and which took four trips
to the dealer before they figured it out.