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Discussion Starter · #1 ·
Big thanks to anyone who can provide suggestions or share insightful experiences. I purchased this 2004 v10 touareg about 2 years ago and drove it successfully for about 8 months. The previous owner had lost his key and had trouble after that with the immobilizer system of which the key is a component and it was in a kind of limp mode as a result. I bought a parts car v10 which was sitting neglected at an import shop and swapped its ignition,kessy,steering column lock, and 2 x ECUs into the first vehicle and it started on those ECU's and ran better, as in having the power of a normal suv but I could tell it did not have full power (slow accl at high speeds, max maybe 140km/h). I love the vehicle and it got me around as I worked to find a solution to the electronics draining the batteries when it was turned off and which battery really mattered. As it turned out only the front battery under the seat was required for the treg to run normally, the problem was all the electronics are tied to that battery and they can develop parasitic draw. So I placed a disconnect switch on the that battery and disconnected the battery when I was not using it, problem solved.

Another few months went by and I notice after trying to pass a slow car that the acceleration and top speed improved and the turbos started working. Soon after there were big power gains and it finally seemed like the vehicle was working properly (max speed 220km/h with hard pulling acceleration). I was overjoyed. However there were some issues I wanted to address. One issue was that there was noticeable diesel vapor coming from the Left fuel pump. At first I thought it was from the coolant heater in the wheel well but when it got worse under hard acceleration in the summer I knew it was from that pump. The vehicle drove fine for about 10k more km but one day driving to town it started taking longer to shift, holding gears until around 2500 rpm and running rougher and then later it went into limp mode. I have a portable tuner from kerma tdi that came with the parts car ECUs that can clear the cel which is normally on anyway but clearing the codes made the engine run better so I did a few times and limped home at 70-80 km and using the manual shift mode because otherwise it was getting stuck in lower gears and not up shifting. I got it home and cleared the codes a few times, reset the throttle sensor and that fixed it again for a few days. Then I drove to town again and the drive there was OK but upon starting it for the drive home the rough running and shifting issues came back. I got it home but it was a struggle (about 70 km/h) and had to clear codes several times to make it back because it kept going limp which shut off the turbos and reduced it to a crawl.

I called my mechanic to come pick it up a few days later and it would hardly idle, ran rough and no power at all. It would stall and not move and regardless of whether codes were cleared the cel stayed on. It has been at the mechanic for 4 weeks + and intakes and egrs were taken apart and cleaned and Left side fuel pump was adjusted to address the leak and the fuel filters were changed but it made no difference it still could barely idle. Starts strong and sounds like it wants to run after a few cranks gets to about 600-700 RPM and sputters out. Not every start is the same and it does not seem that the computer is shutting it down, more like lack of air or not enough fuel or air in lines or something.

I'm not sure what to look at next. I'm wondering if there could be air in the fuel system because of the leaking pump or possibly the pump slowly failed. However when the codes were cleared and it was shifting properly there was plenty of power in those last few days so I think the pumps are/were functional. There does seem to be a connection between fuel pump performance / rough idle and shifting pattern, like the computer is trying to compensate but in the end was unable to. I also considered that all of the fuel vapor may have slowly clogged the air filters but this may be wishful thinking.

The exhaust workshop yellow indicator light would always come on at startup and I thought nothing of it. However during the last few days when it began to run rough again this light would come on during driving sometimes which may have a different meaning. The flashing glowplug light also came on around this time (which I know means an engine or ECU problem). I suspect the ECU is saying something needs to be fixed for it to do it's job. I had the codes checked a few days before the last drive and there were some codes for 2 of the injectors which I thought could be connected to the pump leak / fuel pressure changes. I don't have vcds but I can use the kerma tuner to read the codes in a basic way. I will be visiting the car on the weekend and will write down the codes. Opinions on if this sounds like air in fuel lines, pump failure, exhaust / cat obstructions or anything else I may have not considered welcome and appreciated!
 

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Discussion Starter · #2 ·
Update: Visited the Touareg today and tried a few things but problem is the same or slightly worse. It will crank at around 200 RPM and try to slowly work it's way up to 500 and then sputter out and works back up to 500 and sputter again. Tried this a few times and could not get it to start and idle. A few times it worked up to a fast crank and seemed like it wanted to start but at the point it would sputter and drop RPM again. Checked the codes (1st picture below). I could see some exhaust coming from the passenger side exhaust but not the driver when it was cranking.
Office equipment Gadget Font Space bar Communication Device

I charged the battery and put cables on the contacts under the hood and connected it to my truck battery to keep voltage and reprogrammed the ECU file from the modified Kerma map to the original using the tuner thinking that if the problem was ECU related this might help. Original mapping successfully reflashed but CEL and flashing glow plug remained. Attempted to start a few more times with no success. Same problem. I feel the ECU is working properly. I rechecked the codes and there were a few more using the original ECU file. Looking for any advice on next steps. The presence of exhaust tells me some fuel is getting through but perhaps not enough to start and idle the engine. Also checked the air filters and they looked ok so I don't they are the problem.

Fluid Rectangle Gadget Font Audio equipment
 

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Discussion Starter · #3 · (Edited)
I used a different scanner to check the codes and this is what I found. I also noticed that the indicator for the driver's door being open on the cluster display was not working when the door is open (other doors are showing up on the display). My understanding is opening the driver's door sends a signal to run the pumps in the tank for fuel priming so this is an issue I would like to address to see if it improves the starting.

Codes:
P0671 Cyl 1 Glow Plug Circuit Open (this one has been there for a while when it ran normally)
P0670 Glow Plug Control Module 1 Circuit /Open
P0698 Sensor Reference Voltage C Circuit Low
P0200 Injector circuit open
P2122 Throttle /Pedal Position Sensor Switch D Circuit Low (the is likely fr om resetting the throttle sensor)
P0381 Glow Plug Heater indicator control circuit/open
 

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