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Discussion Starter #1
I'm having a problem with my Touareg (v6 3.2 year 2003).

Check engine light comes up and car is very lean.

Fault codes are the ones for both banks lean at idle and after a while also both banks lean under load.

Fuel trim values > +25% on both banks when i use my scan tool.

First the short fuel trim and after a short while also the long +25% for both banks.

What garage and i already did:

- Vacuum leaks check (smoke test) found a little hole and changed that line.
Did not help. Codes came back.

- Exhaust had a big leak on the front side. Is also fixed by garage. Codes still come back.

- MAF is tested by the garage well within normal operating range.

- The breather valve (PCV valve) was sucking in air also at idle. I also changed that for a new one now works fine but did not fix my trim values that are still the same.

- All other values (o2 sensors, lamda) look good to me. A friend of mine has the same car. Volt values etc look exactly the same. (except for the fuel trim values. his stay near 0 long and short mine shoot up to +25%).

I think the only thing is left for me to check is the Fuel pump (filter). I think that is where the problem is.

The reason i suspect the fuel pump is because when my fuel tank is almost empty (please refuel light comes on) from that moment on the long fuel trim values are returning to normal. (between -5% / +5%)
And if i reset the check engine light the fuel trim values stay between -5 and +5.

I'm guessing that when the refuel light goes on the second fuel pump kicks in and helps the main fuel pump. >> i know know for sure it does. When fuel tank is empty both fuel pump are working. I did some testing and i can hear them both working. When more than 1/4 fuel in fuel tank than the second pump shuts off after 30 seconds after starting up the car

Anyone had this issue before and would this be a dirty fuel filter? Or do you think the main pump is just (half)dead?

Car holds in when refueling and tank is full. stutters until i give it allot of gas than drives ok (but not great) and the fuel trim values are way off +25% on both banks again.
 

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Other leads:
Evaps system (n80)
Fuel cap
Sorry to have hijacked your other thread :)
Do you have vcds. You need a vcds autscan to see if you have other codes.
 

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Discussion Starter #3
Evaps system (n80) = PCV value right? i Changed that one for a new one.

Yep i hope a can do VCDS autoscan soon...
 

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Nope. Evap is a different setup. The valve is on the passenger side. You can remove and check it.
Here is a link to have some info:

 

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Discussion Starter #5
Nope. Evap is a different setup. The valve is on the passenger side. You can remove and check it.
Here is a link to have some info:

https://youtu.be/4IWzZzZb6B8
Did you read through my whole story? i cannot imagine it can be anything different than the fuel system. because i only get the lean condition if 1 pump is working. When both pumps are active no issues.

i think we are talking about the same thing no.. ? it is on the passenger side yes.

 

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Remove and check it before getting a new one as it's a bit expensive and you don't want to be changing parts for the sake of changing parts.

Remove it, use a 12v source to test if it clicks and blocks air if you blow through it. It's number 21 in the diagram, located right behind the throttle body.

You really nead vcds and log the same data on both your touareg and your friend's touareg and compare.
You need to do advanced measuring block logging. Let me know when you get vcds and I will show you how.

You need to do an additional check of all the vacuum system.
Use a carburetor cleaner check.
Check the throttle body is sealed correctly by spraying carburetor cleaner and see if engine revs up.
 

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Discussion Starter #7
Remove and check it before getting a new one as it's a bit expensive and you don't want to be changing parts for the sake of changing parts.

Remove it, use a 12v source to test if it clicks and blocks air if you blow through it. It's number 21 in the diagram, located right behind the throttle body.

You really nead vcds and log the same data on both your touareg and your friend's touareg and compare.
You need to do advanced measuring block logging. Let me know when you get vcds and I will show you how.

You need to do an additional check of all the vacuum system.
Use a carburetor cleaner check.
Check the throttle body is sealed correctly by spraying carburetor cleaner and see if engine revs up.
Thanks :nerd:

You need to do an additional check of all the vacuum system.
Use a carburetor cleaner check.
Check the throttle body is sealed correctly by spraying carburetor cleaner and see if engine revs >> allready did these test and after this also a smoke test on the whole intake systeem >> no leaks
 

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Did you read through my whole story? i cannot imagine it can be anything different than the fuel system. because i only get the lean condition if 1 pump is working. When both pumps are active no issues.

i think we are talking about the same thing no.. ? it is on the passenger side yes.
the n80 is not the pcv. the n80 is located somewhere behind the pcv.

Then replacing the pump might solve it. At least you will know for sure and if not go on with the troubleshooting.
 

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If you think it is the fuel system, why not check to see if the pumps are in spec?

 

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Discussion Starter #11
If you think it is the fuel system, why not check to see if the pumps are in spec?

https://www.youtube.com/watch?v=ZVBaH2jsPg4
Ill first change the filter (allready ordered) the filter on my car has never been changed yet. (233.000 km allready on the clock)if that does not fix it i will bring the car to the dealer to do a fuel delivery check. Than if needed ill change the main pump.

i also posted here just to check if other people ever had the same issue and for future help if mine gets fixed :)
 

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Discussion Starter #12
i also posted a reply on that video of @Edgemotors on youtube about this problem and his guess was also a dirty fuel filter.
 

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If you are changing only the filter element, be very careful of the o-ring during reassembly. This does not apply if you purchased the entire fuel filter assembly.

Also, something else I have noticed. Those plastic fuel hoses inside the tank get brittle with age.

Try not to "stress" the old fuel lines when changing on the filter. No sharp bends, no hard pulls, etc and I think you will be fine.
 

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Discussion Starter #14
If you are changing only the filter element, be very careful of the o-ring during reassembly. This does not apply if you purchased the entire fuel filter assembly.

Also, something else I have noticed. Those plastic fuel hoses inside the tank get brittle with age.

Try not to "stress" the old fuel lines when changing on the filter. No sharp bends, no hard pulls, etc and I think you will be fine.

i purchased the whole thing yes :wink2: thanks for the help.
 

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And let us known how it goes. If you can take pics and give us some feedback that would be great. I might be looking at doing the filter refresh sometime in the not near future. Thanks.


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Discussion Starter #16
And let us known how it goes. If you can take pics and give us some feedback that would be great. I might be looking at doing the filter refresh sometime in the not near future. Thanks.


Sent from my iPhone using Tapatalk

Off-course i will :wink2: hope i can do this next weekend if i receive it before then.
 

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Discussion Starter #19
Read this thread. There are two methods to bypass the main pump and run on the secondary one. This will help you test your theory. There is also good info about changing the fuel pumps and filter there. You neef to empty your tank to make the job easy. Just drive it untill it dies some 400 km from home then flatbed it home to fix the pumps

https://www.clubtouareg.com/forums/f43/stall-around-30-seconds-fuel-pump-43583.html#/topics/43583

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Allot to Read filter not in yet.. but i set up a small laptop with vcds now. Got IT working and tested on the Car. Worked like a charm. Much more errors than the handheld device i used misfires etc. Let me know about the test you wanted me to perform with vcds.

Verstuurd vanaf mijn ASUS_Z01RD met Tapatalk
 

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You can post an autoscan so we can help with the errors and learn.
I'll give you some measuring blocks to test tomorrow. I have a doubt about the o2 sensors. For the moment if you can take a video of the variable intake change-over valve I talked about that would be great. Here is the ssp of this variable intake:
http://www.volkspage.net/technik/ssp/ssp/SSP_212.pdf


To test the change over valve mouvement you need to:
1. Put the camera or phone near the valve.
2. start recording
2. Start the car
3. Rev the engine past 1200 rpm.
4. See how the arm moves up and down.

It should stay up under 1100 rpm and get pulled down above 1100 rpm.
When driving it should go up after 4400 rpm i think. But a stationary test will tell if it's


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