Help needed: High idle/engine load, sudden loss of acceleration/throttle

mistabiggx

Member
Joined
Jan 4, 2019
Location
Accra, Ghana
TDI
Passat B5.5 2005 (3BG)
Hello everyone.

I have a 2005 Passat b5.5 tdi (PD) with 233,000+miles on the odometer. A few months ago, I experienced a sudden loss of acceleration/throttle while on the highway. There was a beep, and the glow plug light started flashing with the "Emissions Workshop" message on the dash. I pulled over, turned the engine off, and back on, and everything was back to normal and so thought I was good until it happened again after 2-3 weeks. Then it happened quite often until it became unbearable. Now, I can't do 5km without this happening, and the sad thing is there is no check engine light, and there are no DTC codes when I connect my generic OBD.

So this is what is happening:
  • when I start the engine, idle stays between 1,100 - 1,200 rpm until I begin to move (rpm usually rises). So rpm never goes back to normal.
  • at idle, the engine load reading is at 50%-52%
  • when the throttle pedal becomes completely unresponsive, I lose my air condition as well. But when I check the readings for throttle position with the OBD, I get accurate readings when press/depress the throttle pedal. This has led me to believe that the throttle position sensor is sending the correct signal but the ECU is refusing to act on it for some reason.

So far, I have changed the engine coolant temperature sensor, oil, oil filter. I am getting very frustrated as I do not have VCDS and it isn't very common in my location.

Any help would be highly appreciated. Thanks in advance.
 
Last edited:

vwztips

Veteran Member
Joined
Aug 30, 2009
Location
Greenville, SC
TDI
2005 Passat GLS Wagon TDI 5 spd manual w/BSM delete 2011 Tiguan TDI/DSG 2005 Audi A4 Avant 6MQ TDI 2011 BMW X5 35d
Check all your turbo hoses for leaks/holes. In particular the hose coming off the turbo and the one entering the anti-shudder valve. Pull them off an inspect thoroughly
 

mistabiggx

Member
Joined
Jan 4, 2019
Location
Accra, Ghana
TDI
Passat B5.5 2005 (3BG)
Check all your turbo hoses for leaks/holes. In particular the hose coming off the turbo and the one entering the anti-shudder valve. Pull them off an inspect thoroughly
I'll try that tomorrow and revert. Thanks man, I really appreciate this.
 

Bell.Lapadula

New member
Joined
Apr 19, 2018
Location
New London Connecticut
TDI
2005 Passat TDI
Yes that is a good idea to check those turbo hoses.
With that many miles you want to keep a good eye on that turbo. I had to replace mine at 118,000 miles. I kept getting smoke out of the exhaust on start up and if I accelerate quickly. Once the turbo was replace that disappeared. It was cheaper to just buy a new turbo then have the old one rebuilt and reinstalled.
 

mistabiggx

Member
Joined
Jan 4, 2019
Location
Accra, Ghana
TDI
Passat B5.5 2005 (3BG)
Check all your turbo hoses for leaks/holes. In particular the hose coming off the turbo and the one entering the anti-shudder valve. Pull them off an inspect thoroughly
I checked all the hoses but didn't find any physical damage and when I fixed everything back, the problem was still there. Perhaps I didn't do this right. Is there any special way I should have done this? A guide on here maybe?

Yes that is a good idea to check those turbo hoses.
With that many miles you want to keep a good eye on that turbo. I had to replace mine at 118,000 miles. I kept getting smoke out of the exhaust on start up and if I accelerate quickly. Once the turbo was replace that disappeared. It was cheaper to just buy a new turbo then have the old one rebuilt and reinstalled.
Thanks for the advice. I've actually considered that, but would a bad turbo cause these symptoms?
 

vwztips

Veteran Member
Joined
Aug 30, 2009
Location
Greenville, SC
TDI
2005 Passat GLS Wagon TDI 5 spd manual w/BSM delete 2011 Tiguan TDI/DSG 2005 Audi A4 Avant 6MQ TDI 2011 BMW X5 35d
Next check vacuum from tandem pump to see if you have 25 hg(?) Of vacuum.

Then check vacuum line from tandem pump to N75 an from N75 to turbo.

If all that checks out remove the vacuum line from turbo, cut off 25mm of line and put back on turbo. (In fact you may want to try that first)
 

mistabiggx

Member
Joined
Jan 4, 2019
Location
Accra, Ghana
TDI
Passat B5.5 2005 (3BG)
Next check vacuum from tandem pump to see if you have 25 hg(?) Of vacuum.

Then check vacuum line from tandem pump to N75 an from N75 to turbo.

If all that checks out remove the vacuum line from turbo, cut off 25mm of line and put back on turbo. (In fact you may want to try that first)
Oh that reminds me.

About 2 weeks ago when I was trying to fix this problem, I noticed the vacuum line that goes from the n75 to the turbo had burnt and had a hole in it, and so I replaced the whole thing. I was very hopeful that was the cause of my problems but it didn't fix it. What surprises me is how I didn't feel any difference in the performance of the car with a hole in that vacuum line. All this while, the car's performance hasn't been affected (or maybe very slightly that I didn't even notice).

My understanding is that, with a hole in that vacuum line, the wastegate wouldn't be actuated (properly). So I want to ask this: what could be the implications of the wastegate not actuating?

I'm still going to get a vacuum gauge to check the readings

Many thanks.
 

Bell.Lapadula

New member
Joined
Apr 19, 2018
Location
New London Connecticut
TDI
2005 Passat TDI
Thanks for the advice. I've actually considered that, but would a bad turbo cause these symptoms?
I do NOT know, perhaps not.

However, I did have an issue once with with lights blinking (coming on then going off) on the dash panel, some icon saying 'you have and issue'. I am not sure which icon it was now. I did not keep that good of detailed record.
But the solution was, the repair shop (VW), replaced the 'Throttle Body'.
$620, plus labor $300, ouch. But the issue went away.

I know what you are thinking, they were making it up and over charging me. But they seem generally honest. They were pretty excited that they had found and isolated the issue. They tried to comfort me on the cost because they new it was a lot for that old car. It was a good size dealer ship, one of many dealers that pooled their resources. I felt pretty good about the service.

My little sweet hart car is running great. I want to keep it that way. I just thought I would post something. I am not really sure I am of any help. I just like reading this stuff and learning about the car. Good luck on your repair.
 

vwztips

Veteran Member
Joined
Aug 30, 2009
Location
Greenville, SC
TDI
2005 Passat GLS Wagon TDI 5 spd manual w/BSM delete 2011 Tiguan TDI/DSG 2005 Audi A4 Avant 6MQ TDI 2011 BMW X5 35d
Oh that reminds me.

About 2 weeks ago when I was trying to fix this problem, I noticed the vacuum line that goes from the n75 to the turbo had burnt and had a hole in it, and so I replaced the whole thing. I was very hopeful that was the cause of my problems but it didn't fix it. What surprises me is how I didn't feel any difference in the performance of the car with a hole in that vacuum line. All this while, the car's performance hasn't been affected (or maybe very slightly that I didn't even notice).

My understanding is that, with a hole in that vacuum line, the wastegate wouldn't be actuated (properly). So I want to ask this: what could be the implications of the wastegate not actuating?

I'm still going to get a vacuum gauge to check the readings

Many thanks.
If waste gate is not/does not move you get no boost. You can move it through Vag-Com or put a vacuum pump on the waste gate nipple and see if the rod moves.

Could be stuck vanes too but check all the easy stuff first.
 

mistabiggx

Member
Joined
Jan 4, 2019
Location
Accra, Ghana
TDI
Passat B5.5 2005 (3BG)
I do NOT know, perhaps not.
However, I did have an issue once with with lights blinking (coming on then going off) on the dash panel, some icon saying 'you have and issue'. I am not sure which icon it was now. I did not keep that good of detailed record.
But the solution was, the repair shop (VW), replaced the 'Throttle Body'.
$620, plus labor $300, ouch. But the issue went away.
I know what you are thinking, they were making it up and over charging me. But they seem generally honest. They were pretty excited that they had found and isolated the issue. They tried to comfort me on the cost because they new it was a lot for that old car. It was a good size dealer ship, one of many dealers that pooled their resources. I felt pretty good about the service.
My little sweet hart car is running great. I want to keep it that way. I just thought I would post something. I am not really sure I am of any help. I just like reading this stuff and learning about the car. Good luck on your repair.
I get your point and I'm grateful. I just wish I knew a good VW-specific repair shop around here.

If waste gate is not/does not move you get no boost. You can move it through Vag-Com or put a vacuum pump on the waste gate nipple and see if the rod moves.

Could be stuck vanes too but check all the easy stuff first.
I'll check those as soon as I get the vacuum gauge/pump. Many thanks
 
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