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Matt
Matt, Engineer
Category: VW
Satisfied Customers: 21357
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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It gives p0129, 06 vw jetta 2.0t, yes, it also gives p507,

Customer Question

it gives p0129
JA: What is the model/year of your VW?
Customer: 06 vw jetta 2.0t
JA: Are you fixing your Jetta yourself? What have you tried so far?
Customer: yes
JA: Anything else you want the mechanic to know before I connect you?
Customer: it also gives p507, p2279 and p2187
Submitted: 4 months ago.
Category: VW
Expert:  Matt replied 4 months ago.

Hello

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane or brake cleaner around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.

if the engine condition is the same then chances are the meter or the connection to it is faulty

It’s also worth cleaning the MAF sensor wires, as they can get coated with dirt over time which then offsets the reading

Use some contact cleaner or brake cleaner to spray onto the wires to remove the dirt – on no account touch the wires with anything as they are very fragile

Customer: replied 4 months ago.
Is this causing all 3 generated code?
Expert:  Matt replied 4 months ago.

Hello

Yes its quite possible

certainly I'd fix the air leak next and see what codes then remain

Customer: replied 4 months ago.
I have looked for leak everywhere, no sign of it, if i clear codes the p129e comes back right away.
should i focus on fuel pressure first?
What should be fuel pressure on low side, can i use MODUS reading for fuel pressure?
Expert:  Matt replied 4 months ago.

hello

low side there should be 3 to 5 bar pressure

its variable as its controlled by the ECU

at idle though with no load its 3 bar

and I think you'll need to plumb in a pressure gauge to check it as the pressure sensor is on the high side

Customer: replied 4 months ago.
I read the fuel pressure with a gauge, it reads between 2 and 7 bars, the car also shake bad
Customer: replied 4 months ago.
I read the fuel pressure with a gauge, it reads between 2 and 7 bars, the car also shakes bad.
Expert:  Matt replied 4 months ago.

Hello

it shouldn't be fluctuating that much

I'm wondering if you have a faulty pressure sensor or a faulty high pressure pump thats causing the high pressure side

can you monitor the high side fuel pressure for 20 seconds at idle at tell me what you see?

Customer: replied 4 months ago.
where is high pressure side, i have been working with driver side inlet where it has a release valve for gas
Expert:  Matt replied 4 months ago.

hello

if I've got my model years right the 2006 VW turbo engine is a direct injection unit / GDi ?

so the fuel injection is done with a high pressure system thats driven off an engine driven pump, this pump is fed with the in -tank pump at 3 -5 bar and the engine pump increase this to 50 to 200bar

it this 'high side' pressure that you can monitor with the scan tool

now if its not a TFSI unit and its only on PFi then there's no pressure sensor,

Customer: replied 4 months ago.
Modus scanner does not tell me the high fuel pressure, I am still in need of determining the cause of engine shakes and fault codes.
can you help me?
Expert:  Matt replied 4 months ago.

hello

can you confirm if your engine is a high pressure TFSI / direct injection unit?

if its not then you will need an old fashioned fuel pressure gauge to push onto the fuel rail to confirm that its getting 3- 5bar of pressure on a running engine

Customer: replied 4 months ago.
I have FSI Engine
Expert:  Matt replied 4 months ago.

hello

Ok in that case that's the 1st generation direct injection engine

this document highlights the differences between VW engines

http://bd8ba3c866c8cbc330ab-7b26c6f3e01bf511d4da3315c66902d6.r6.cf1.rackcdn.com/FSIvTSI.pdf

so there should be a high pressure fuel sensor that can be read with a scan tool

as I suspect that you have either a faulty high pressure pump or the low pressure pump in the tank is faulty and stalling the High pressure pump

Customer: replied 4 months ago.
I tried a different scanner to read high fuel pressure but it was not offered so I am still trying to figure out a defective part from both fuel pumps and fuel pressure sensor.
Is there a fuel pressure sensor in this car?
Remember the low side pressure fluctuate between 20 and 70
Customer: replied 4 months ago.
Have you got this?
I tried a different scanner to read high fuel pressure but it was not offered so I am still trying to figure out a defective part from both fuel pumps and fuel pressure sensor.
Is there a fuel pressure sensor in this car?
Remember the low side pressure fluctuate between 20 and 70
Customer: replied 4 months ago.
Please answer my question, I still have problem.
Expert:  Matt replied 4 months ago.

hello

all GDi systems have a pressure sensor as the pump is variable in its displacement

so a faulty pressure sensor will result in the pressure not being controlled correctly and normally its left fully open so you don't get full 20Mpa ( 200bar) and as a consequence very down on power

if the low side pressure is bouncing around at idle then its quite possible the low pressure pump is faulty or it has a blocked pump filter

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