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Discussion Starter #1
I have a 2004 T1 with the 4.2L V8 with about 155,000 miles on it. Two days ago (after sitting in lots of stop-and-go traffic) it started idling VERY rough, the check engine light was on, and then flashing and then the engine would stall.

Starting it up again it would seem to run fine for a few minutes and then repeat the same symptoms before stalling. Sometimes the engine light would flash, sometimes not.

I also noticed that if I would start it and quickly put it in drive and step hard on the gas it will take off like a rocket (as usual), but after slowing down it will stall out again.

When I got it home I pulled codes with my ODB-II reader and cleared the MIL. The codes are below;

[5 Confirmed Codes]
P0305 - Cylinder 5 Misfire Detected
P0421 - Catalyst 1 Efficiency Below Threshold Bank 1
P0301 - Cylinder 1 Misfire Detected
P0171 - System Too Lean Bank 1
P0300 - Random/Multiple Cylinder Misfire Detected

[1 Pending Code]
P0174 - System Too Lean Bank 2

What's strange is that I've driven it on several short test drives since then and the symptoms are the same, stalling out every 30 seconds to 2 minutes depending on driving pattern, but NO engine light has come back on.

I've read many posts about similar issues, but none that seemed to come on so suddenly and be so severe. I plan to check for vacuum leaks, check spark plugs, ign coils and MAF, and then move on to O2 sensors and (hopefully not) Cat converters.

Does anyone that's experience similar issues have suggestions on the best place to start?

Thanks, ALT-B
 

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Discussion Starter #3
Haven't filled gas recently, and change seemed very abrupt - but I was going to fill with fresh gas and maybe injector cleaner, to see if it makes a difference.

Also replacing plugs today.
 

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Discussion Starter #5
After replacing spark plugs and cleaning MAFs, the same symptoms continue, still no CEL, but now my ODBII reader is showing two "Pending Codes";

P2231 - O2 Sensor Signal Circuit Shorted to Heater Circuit Bank 1 Sensor 1
P2234 - O2 Sensor Signal Circuit Shorted to Heater Circuit Bank 2 Sensor 1

So this seems to be pointing me to a failed O2 sensor (or two)... anyone know how to zero in on which one(s) this may be referring to?

Thanks, ALT-B
 

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Bank 1 is passanger side and sensor 1 is pre catalytic converter, take your pcv breather valve out and make sure it's not full of gunk. rear oxygen sensors (ex: B1S2) do not have an affect on the drivability. it sounds like you have more than 1 problem, and oxygen sensor will not cause an engine to stall.

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also check fuel pressure, if the pressure drops of to zero after 20 seconds of run time replace the passanger side fuel pump

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Discussion Starter #8
Thanks Dpkhym, I wish I had seen your post regarding O2 sensors not causing the engine to stall before I replaced the O2 sensor.

After my last post, a test drive (remember it will drive if I stay on the accelerator hard, only dies when I lift off the pedal) brought the CEL back on, and only showed a P2234 Code (O2 Sensor, Bank 2, Sensor 1 - which I understood to be the 'upper' pre-cat O2 sensor on the driver's side), so I replaced that O2 sensor.

I haven't taken another test drive - but after installing it would run, and idle for 20-30 seconds, and then stall out just as before. I restarted it 4 or 5 times, all with the same result.

Dpkhym, from your posts above it sounds like I should check the PVC breather valve (would this contribute to stalling?) and investigate the passenger side fuel pump.
If the pass fuel pump was bad/going bad - would the vehicle still feel like it had full power when accelerating hard? (5,000+ RPMs and 80+ MPH?)

Thanks, ALT-B
 

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Discussion Starter #9
marshatherton, I haven't done the fuel filter(s) (is there one for each fuel pump?) - could this also cause the "stall after 30 seconds" issue while idling, but not cause a problem when on the accelerator hard?
 

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Is it exactly 30 seconds? If it's exactly, it's probably not the fuel filter. But i always say, start with the easiest first. Fuel filters are relatively easy to replace.

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Discussion Starter #11
I haven't timed it, so I'm not sure it's exactly 30 seconds - but pretty close. I'm going to try get a filter and start there.
Is there one filter for each fuel pump?

Thanks.
 

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Looks like it's just one, and fairly easy to replace.

https://youtu.be/2Rd3Fvo1zWs

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it's expensive unless you can find the actual element, If you go to the dealership they only sell the flange/filter assembly. I would say it's not the filter, that is not to say it's not needing replacement for general maintenance.

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This video could be useful. First tests the fuel pressure, then later tests the fuel flow.
\
 

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Discussion Starter #15
Thanks nickyt, I found the same video earlier this evening - I'll be running those tests after work tomorrow. So hopefully that will lead to some clarification!
 

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Discussion Starter #16
I was able to run the tests in the video last night, and found the pressure tests went well until the usually 30-31 second stall would occur.

When jumping the relay posts (for the volume tests) I could not get the passenger side (right I believe) pump to run at all. So either that pump is dead, or there is a wiring problem between the fuse box and the pump.
More testing to do tonight.
Does anyone know if there is an easy was to manually jump (with 12v) the pump where the 4 prong wiring plug connects without removing the pump?

Thanks, ALT-B
 

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common enough problem for the main fuel pump to fail, the left fuel pump primes the system then the right fuel pump keeps it pressurized. I do believe the left fuel pump kicks on at high load demand ( wide open throttle) so that would explain why you can keep it running under such conditions. you will have to remove both access flanges to remove the right fuel pump

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I have experienced a similar problem on a couple of cars and it turned out to be a failed cat in each case.
What happened in my experience was that the honeycomb in the cat would break apart and you would end up with a ball of honeycomb that bounces around inside the cat until it get stuck in the right spot by the exhaust pressure and the engine stalls due to a plugged cat.
I was able to confirm this by pulling the second O2 sensor. When the "ball" is letting exhaust out then you get lots of pressure at the hole where the 2nd O2 sensor was.
When the cat gets plugged by the ball then pressure drops to 0.

Just a thought.
 

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Discussion Starter #20
Thanks Dpkhym,

I was able to see just under 11v going to the connector plug on the passenger side pump in my testing tonight, but only a faint 'click' coming from the pump location when sending power to it.

So I think I've gotten to the core issue being the passenger side (right side) fuel pump failure.

I'll post again after installing the pump to confirm that the issue was fixed.

- ALT-B
 
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