Intermittent Acceleration Problems

noelchenier · Aug 27, 2019

Hi everyone

I have a 2006 Jetta TDI with 425,000kms

Recently I started having intermittent issues with acceleration driving my TDI.

It tends to happen more when I am accelerating up inclines, but I have noticed it on flat.
Put the pedal to the floor, no acceleration at all.

The gear drops to 4/5, speed drops.
Pull over, shut the car off.

Start it up, acceleration is back to normal.

Using an ODB scanner, it shows P0404, and occasionally P2413.

Took it to the local VW shop (not the dealership) and of course when they take it out, works flawlessly and there is no obvious cause.

Thankfully these guys aren't the type to start replacing expensive parts for the hell of it, but I use this car to commute 3 hours a day and need to get back and forth safely.

So I'd like to try to fix this, or decided if it's time to buy a new car.

The only work that has been done recently was the fuel filter being changed about 5,000kms ago.

Any suggestions?

Also, I'm a not a mechanic, so if I'm not giving enough info, please let me know.

Noel

mextdi · Aug 27, 2019

Hi Noel, welcome to the forum!

As far as preventive maintenance or major repairs, have you done anything to it lately?

The easiest thing to do that JUST might help is to pour some diesel mechanic or Liqui Moly diesel specific product into the gas tank. That might help clean things out if that is the case. That sometimes helps. Otherwise, you might have a million different things going on, but at that mileage, it could be a turbo going out or a faulty camshaft or something similar. Try running that stuff in your tank and report back.

Lastly, there might be some TDI guru in your neck of the woods for sure, someone might have a bit of free time to come help you out. I'd look into that as well.

Cheers!

MrBigTruck · Aug 27, 2019

One of my 2006 Jettas does this. It happens infrequently enough that I have ignored it and driven it and put about 25,000 miles on it in the past year. Mine has a manual transmission so I don’t pull over to switch it off and back on. I just do it while I’m rolling and keep driving. I am guessing that there is some chafing in the engine wiring harness but it could also be the turbo on its last legs.

noelchenier · Aug 28, 2019

Thanks for the reply MexTDI!

Only recent maintenance was fuel filter and air filter changed.

Oil change was done about 7,000kms ago (Rotella T6)

Thank you for the suggestion, I will try to source the products listed and see if that helps!

Noel

mextdi said:
Hi Noel, welcome to the forum!

As far as preventive maintenance or major repairs, have you done anything to it lately?

The easiest thing to do that JUST might help is to pour some diesel mechanic or Liqui Moly diesel specific product into the gas tank. That might help clean things out if that is the case. That sometimes helps. Otherwise, you might have a million different things going on, but at that mileage, it could be a turbo going out or a faulty camshaft or something similar. Try running that stuff in your tank and report back.

Lastly, there might be some TDI guru in your neck of the woods for sure, someone might have a bit of free time to come help you out. I'd look into that as well.

Cheers!

noelchenier · Aug 28, 2019

Thanks for the reply MrBigTruck!

Sort of what I'm doing, as it has be infrequent in my case as well.

Please forgive my ignorance (again, I'm not a mechanic and have limited knowledge about cars), but could you explain what you mean by "just do it while I'm rolling and keep driving"?

I was wondering if it could be something with the wiring harness as well.

When I look at possible solutions, it all seems expensive.
Replacing the engine harness, replacing the EGR valve, deleting the EGR...
Pretty much all of those involve parts that are $200-$300 US, which will be more for me since I'm in Canada.
And they may or may not be the problem.

Thanks
Noel

MrBigTruck said:
One of my 2006 Jettas does this. It happens infrequently enough that I have ignored it and driven it and put about 25,000 miles on it in the past year. Mine has a manual transmission so I don’t pull over to switch it off and back on. I just do it while I’m rolling and keep driving. I am guessing that there is some chafing in the engine wiring harness but it could also be the turbo on its last legs.

mextdi · Aug 28, 2019

Thinking about this again, it could be that the car goes into limp mode. It goes into limp mode for various reasons, overboost, underboost, senses something not right with the engine, etc... If you are getting codes for the EGR, it could be something related to the N75 valve, the turbo, the EGR itself, it could be many things. Limp mode usually can be stopped when the ignition is cycled on and off, that is what MRBIGTRUCK is doing, he is turning his car on and off on the fly, easy to do if you have a manual, EXTREMELY DANGEROUS on an automatic.

Even though your car doesn't have a ton of miles, I'd recommend checking the vacuum lines in the engine bay, especially the ones to and from the N75 and the bigger line that connects to the tandem pump, all those tend to give people trouble. This would be a cheap fix. Another cheap fix, if the turbo is having issues is to do the zip tie fix. It is ghetto, but it is cheap. Research the zip tie fix, it might help you get a bit more miles out of your car.

sptsailing · Aug 28, 2019

This behavior would be consistent with vacuum inadequate to operate the turbo, which in turn would send it into limp mode, resulting in exactly the behavior you notice. I recommend doing a thorough check of all vacuum system components. My TDI had a defective vacuum reservoir, then later developed a cracked plastic vacuum line that was connected to the brake booster.

The difference between uphill and flat terrain limp mode experience is entirely related to the difference in torque requirements.

noelchenier said:
Hi everyone

I have a 2006 Jetta TDI with 425,000kms

Recently I started having intermittent issues with acceleration driving my TDI.

It tends to happen more when I am accelerating up inclines, but I have noticed it on flat.
Put the pedal to the floor, no acceleration at all.

The gear drops to 4/5, speed drops.
Pull over, shut the car off.

Start it up, acceleration is back to normal.

Using an ODB scanner, it shows P0404, and occasionally P2413.

Took it to the local VW shop (not the dealership) and of course when they take it out, works flawlessly and there is no obvious cause.

Thankfully these guys aren't the type to start replacing expensive parts for the hell of it, but I use this car to commute 3 hours a day and need to get back and forth safely.

So I'd like to try to fix this, or decided if it's time to buy a new car.

The only work that has been done recently was the fuel filter being changed about 5,000kms ago.

Any suggestions?

Also, I'm a not a mechanic, so if I'm not giving enough info, please let me know.

Noel

noelchenier · Aug 29, 2019

Thanks for the reply sptsailing!

I'll get the garage to check it out.
But would something like this create a more constant issue, instead of one that so far has only happened two or three times in the past two/three weeks?

Noel

sptsailing said:
This behavior would be consistent with vacuum inadequate to operate the turbo, which in turn would send it into limp mode, resulting in exactly the behavior you notice. I recommend doing a thorough check of all vacuum system components. My TDI had a defective vacuum reservoir, then later developed a cracked plastic vacuum line that was connected to the brake booster.

The difference between uphill and flat terrain limp mode experience is entirely related to the difference in torque requirements.

rbell · Sep 5, 2019

I have been having the same issue in my 06... As far as I can tell, the vacuum lines seem good, but I also have dragging brakes... So maybe a vacuum line going to the booster would cause both of these? I was leaning more towards the N75 valve... but I would be curious on people's thoughts there.

Intermittent Acceleration Problems

noelchenier

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mextdi

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MrBigTruck

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noelchenier

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noelchenier

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mextdi

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sptsailing

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noelchenier

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rbell

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