Diagnosing and Fixing Limp mode for A4 1.9TDI [low power troubleshooting]

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
Quite a bit of resistance. Thumb-hurting resistance. Better if you use a mity-vac to apply the vacuum - that way you're testing the whole actuator, not just the veins.
 

PrintSmith

Well-known member
Joined
Dec 28, 2005
Location
Bailey, CO
TDI
2003 Jetta TDI - RIP June 2016 - 470,000 on clock. 2004 Jetta TDI Sport new to me June 2016
Good to know it was supposed to be difficult, and it was. Thought I could borrow a vacuum tester from the local parts store, but the tool measures vacuum, doesn't create it, or at least enough of it, so I kinda got screwed there. But, when I did test the vacuum from the main line it was about -15 inHg, far below what it should be based on the information upthread. Took some Gorilla tape and sealed off that first connection - Viola!! - it pegged the tester, which only goes up to -20 inHg. Will drive it home again tonight and see if I get the code again.

Thanks for all the help folks. If it ends up being the vacuum pump itself I'll probably have to source that because I'm sure your run of the mill parts store isn't going to carry it. Any suggestions for the Denver area?
 

strictlysmoke

Veteran Member
Joined
Sep 5, 2006
Location
baltimore, md
TDI
golf IV
there is something interesting for u guys t think about. usually in 4th gear in a hard pull it feels as if one of the turbo hoses blows off (limp mode), but i get no engine light. now here is the tricky part when i turn the car off and attempt to turn it back on all the lights start to flicker and the car is hard to start, seems as if u were starting a cold car tat has been sitting for a couple of days. once up and running again no problems.
 

dilkie

Well-known member
Joined
Aug 24, 2008
Location
Ottawa
TDI
'01 Golf, '06 Golf, 90 Jetta
Hey SS, I get the same thing in my old '01 Golf. I *think* because I've blocked off the EGR hose. Mostly happens when I'm towing a trailer on the hi-way and am doing full power and let the rpm's get up over 2500. What I do is stupid, don't follow me... I just leave the car in gear and turn off the engine and back on again (being careful not the take the key out and lock the steering wheel), wait a second or two for things to settle (no throttle during this whole time) and limp mode is gone. As least until I overdo it again. But for a 14yr old car with 500K kilometers on it, I can't complain too much. Not sure what, exactly, is causing it but the car is so rusty now that it's not worth tracking down and spending any money on it.
 

PrintSmith

Well-known member
Joined
Dec 28, 2005
Location
Bailey, CO
TDI
2003 Jetta TDI - RIP June 2016 - 470,000 on clock. 2004 Jetta TDI Sport new to me June 2016
OK, I am able to get the vacuum up to about 23.5 inHg, and I've plugged the line coming off the brake booster hose directly into the N75, but I am still getting P0299 codes. Next up is trying to pull vacuum directly to the actuator, hopefully that can be done with everything still on the motor. Getting a used vacuum pump from a guy in Monument, might have time to put that on before heading up the mountain tonight. Wish me luck, I'm going to need it I think.

Edited to add - actuator not holding vacuum. Can get about 12 inHg by constantly working the hand pump, but once I stop the reading immediately drops back down to 0. Hopefully the guy in Monument has one of those for sale too - we'll see . . .
 
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wes2233

Veteran Member
Joined
Oct 3, 2014
Location
Chico CA
TDI
2002 Jetta Tdi, 2005 Tdi Jetta Wagon
So i was on vacation and my car blew a turbo taking off from a stop light, brought it into the shop and turbo spools had blown apart. The business cleaned the engine out and slapped on a new turbo. The car as an employee stated "ran poopy" idiot. So we took it home and have been battleing the car ever since. The car can be floored in first gear and will not go above 2800 rpm it will sit there and billow out black smoke out the exhaust. But if you let off the gas and get on it again it will go past and drive like normal until you let off again. I checked the TPS with VCDS and it is good. The only codes that the car is throwing is code p0234 turbo overboost. and it is also throwing a code for baromic pressure sensor high input. also it is telling me that the number 1 glow plug is bad. the brake lights are working the Maf has been replaced twice the fuel filter has been replaced all vacume lines have been checked actuator has been checked the vacume pump has been replaced endless amounts of things have been checked Please help me ive allready spent 2,500 on stupid repair shops to fix stuff that didnt need to be fixed trying to fix this car. the car when going up hill or under a load will throw limp mode. please help me im out of ideahs
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
What was tested on the actuator? Was it just tested to hold vacuum or was it tested for start of actuation and end of actuation?
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
So the adjustment of the actuator wasn't tested. Just knowing that it holds vacuum isn't enough. The actuator needs to start moving at about 3-4 Inches vacuum and hit the stop at 18 inches vacuum.
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
What kind of turbo got "slapped on it". What did it cost you? Does it indicate what it is on the receipt?

An overboost code and no power above 3500 or so? Black smoke?

It might be interesting to log some runs - MAP act/request MAF act/request might help.

Also, was there a bunch of oil in the boost system? Could you have ingested some when the turbo blew?
 

wes2233

Veteran Member
Joined
Oct 3, 2014
Location
Chico CA
TDI
2002 Jetta Tdi, 2005 Tdi Jetta Wagon
What kind of turbo got "slapped on it". What did it cost you? Does it indicate what it is on the receipt?

An overboost code and no power above 3500 or so? Black smoke?

It might be interesting to log some runs - MAP act/request MAF act/request might help.

Also, was there a bunch of oil in the boost system? Could you have ingested some when the turbo blew?
the impellars in the turbo blew apart and broke the oil line on the turbo and oil got sucked into the engine. The turbo that got put on was another oem turbo from a dealership. The shop i brought it to bought it from a dealership. I am not positive that they adjusted the actuator correctly
 

wes2233

Veteran Member
Joined
Oct 3, 2014
Location
Chico CA
TDI
2002 Jetta Tdi, 2005 Tdi Jetta Wagon
The car stops accelerating at 2800 rpms and black smoke out the exhaust it wont go past this if you hold it on. but if you let off and get back on it again it will go past this "block"
 

PrintSmith

Well-known member
Joined
Dec 28, 2005
Location
Bailey, CO
TDI
2003 Jetta TDI - RIP June 2016 - 470,000 on clock. 2004 Jetta TDI Sport new to me June 2016
Finally got the car running right today. In addition to the bad vacuum pump (>15 inHg) and actuator that wouldn't hold vacuum, the N75 was bad, which I found out, thanks to the detailed OP, by switching the N75 and the N18 and going for a test drive. Car ran beautifully once the solenoids were switched - no codes and was able to gain speed driving up Mt Vernon Canyon (avg 6% grade for those outside of Colorado) in overdrive once again. Curious to hear what others think about one weak link in the chain causing a cascade effect on the other parts and resulting in their failure. That all 3 parts (pump, actuator and solenoid) needed replacement makes me wonder about that possibility.

Thank you, thank you, thank you to all who know these engines like the back of their hand and pass along that knowledge to the rest of us and to Fred and the rest of the crew who keep this invaluable resource a few keystrokes and clicks away. All of you have literally saved me hundreds of dollars in getting my Jetta running the way it should. May your kindness be returned to you 10 fold.
 
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tactdi

Veteran Member
Joined
Jun 21, 2010
Location
North Carolina
TDI
2005.5 Jetta
The car stops accelerating at 2800 rpms and black smoke out the exhaust it wont go past this if you hold it on. but if you let off and get back on it again it will go past this "block"
If it does this each and every time, then I agree with whitedog, that the turbo actuator needs adjusting. Search for actuator adjusting or the
tie wrap mod. A new turbo should not have the tie wrap mod performed, the actuator should be adjusted properly, the tie wrap mode is the easy method to adjust the actuator to account for turbo vane wear.

With a turbo with miles on it, the experience of engine unable to rev past about 2800 RPMs without lifting and blowing black smoke out the exhaust, is sticky turbo vanes.
 

strictlysmoke

Veteran Member
Joined
Sep 5, 2006
Location
baltimore, md
TDI
golf IV
I have been adjusting my boost valve controller and discovered that when the boost valve is in the open position turbo gets high spikes close to 25lbs when it closed sed the controller half way it was holding boost close to 25lbs on hard pulls in 3rd, 4th and 5th gear. Starting to think that the actuator may need to be adjusted.
 

wes2233

Veteran Member
Joined
Oct 3, 2014
Location
Chico CA
TDI
2002 Jetta Tdi, 2005 Tdi Jetta Wagon
I made an appointment for tommorow "wednesday" to get the actuator inspected and tightened. So what exactly should i tell them to inspect when i get to the shop?

The stop screw?
Vacume?
vacume under boost?
 

wes2233

Veteran Member
Joined
Oct 3, 2014
Location
Chico CA
TDI
2002 Jetta Tdi, 2005 Tdi Jetta Wagon
Turns out the people who installed my "Brand new turbo" didnt instal it right! so now i have to go and buy another turbo from a good friends shop and have it installed correctly. well see where this goes!
 

PrintSmith

Well-known member
Joined
Dec 28, 2005
Location
Bailey, CO
TDI
2003 Jetta TDI - RIP June 2016 - 470,000 on clock. 2004 Jetta TDI Sport new to me June 2016
OK, so I switched the N75 and the N18 last week before heading out of town for a week and the vehicle started running right. Now I'm back in town and wondering how long can I get away with running the N18 instead of the N75 and what problems might a bad N75 cause with the EGR system? Anyone have any experience with the above?

We're due to get a foot or two of snow this weekend in my neck of the woods, so I won't be driving it much the next couple of days, but I don't want to ruin the N18 and have to replace it as well by leaving it in place of the N75 too long.
 

TysonReece

New member
Joined
Feb 6, 2015
Location
Toronto
TDI
2006 Jetta TDI
2006 jetta tdi mkv, turbo lag, limp mode and shaking idle

Hi, ive had this car for almost a year and a half now, it has a malone stage 2 tune and no CAT or exhaust system, it has 268000 km on it, recently changed the timing belt and water pump, flywheel and clutch assembly along with all my glow plugs. Ive been going into limp mode for about a year I was ignoring it and just avoiding triggering it but after replacing everything else I want to deal with. I started with the MAF unplugged I have no change in power and no CEL on so I replaced it but still having the same behaviour. I have checked my vacuum lines they are all holding suction, I had my air intake and intake manifold cleaned which increased my mileage but I'm still feeling a turbo lag and can still go into limp mode. I Purchased VCDS to try and help, in meas. Blocks no numbers seem out of the ordinary, I performed the n75 test and the actuator did move but minimally, I am unsure of whether this indicates a bad n75, my actuator needing adjusting, or my actuator actually needing to be replaced, any help would be greatly appreciated. The VCDS reading showed at idle a difference of 960 (specified boost) and 890 (actual boost) and at 2500 rpm in the third it was 1200 (specified) and 1000 (actual).
 
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nadroba

Veteran Member
Joined
Mar 22, 2010
Location
Guatemala
TDI
2004 Jetta, 2005 Jetta
You have a lack of boost pressure. I assume you did the N75-N18 swap test. You have some tests to do!
1) Test for vacuum at the big vacuum hose that comes out of the vacuum pump. You need to have at least 25 mmHg vacuum there, if not you have to replace or rebuild your pump.
2) Test for vacuum at the vacuum hose that enters the actuator. There should be at least 18mmHg or more. If you don't have enough vacuum here check the lines (vacuum hoses) or replace them all!
3) Apply vacuum directly to the actuator. It should begin its movement by 3mmHg and stop completely at 18. Also the actuator should hold vacuum. If all this checks out, then.....
4) You have your turbo vanes stuck. Remove the actuator adjustment nuts, be careful to make a mark where were they before removing this will save you a lot of work after. Remove your downpipe and apply a generous amount of easy off oven cleaner while you try to move the vanes until you feel a free movement (I prefer the spray easy off) and always protect your hands and eyes.

And at the end if your vanes are not stuck you have a bad turbo ?


Sent from my iPhone using Tapatalk
 

Rhh

Member
Joined
Feb 24, 2014
Location
Vancouver
TDI
02 Jetta
Ok, I'm going to add my woes to this thread in hopes that someone can point me in the right direction.....

I've read and taken the advice above in the original post.
Not sure if it's turbo time.

2002 Jetta TDI with ALH engine...365,000 km. I've owned it since new.
I've experienced several years of limp mode occurring (as prescribed) on long trips when hauling hard up hills with a heavy load etc.

In recent months the limp mode has been occurring more frequently and on routine trips around town. Additionally I was getting a bit of hard brake only occasionally though. The cycling ignition worked to reset the turbo but sometimes MIL And sometimes not.

In an attempt to solve this problem I've taken the following steps:

-read this thread about limp mode :)
-replaced air filter
-tried MAF Test (disconnected it and the power sucked just as bad, no improvement)
-replaced a worn seal in the vacuum pump (where it bolts onto the head)
**this actually fixed the hard brake problem (or at least it hasn't happened since)
-replaced all vacuum lines with proper non-collapsing lines
-intake manifold and EGR cleaned out
-new turbo actuator as the old one was likely the initial problem.

After these were done the car ran great for a day.

The next day it started and ran but without any turbo. No MIL.

Now the car is running full time as if it has no turbo at all.

I swapped out the vacuum pump for another one as the old one was a bit weak (but still producing vacuum) There is no turbo whine or spooling noise, No MIL and no clue what to do next other than post here.:confused:
 

MVP

Veteran Member
Joined
Feb 15, 2015
Location
Litchfield Park, AZ
TDI
2003 Jetta Wagon, GLS 5-speed, Baltic Green Past: 2001 Golf 4-door, GLS 5-speed
Now the car is running full time as if it has no turbo at all. :confused:
My Golf has had the same problem since I bought in a month ago. I'm interested in what it ends up being. So far I have not diagnosed like you, but everything you have listed is on my To Do list.

I hope some you get some hits and good advice - it will help me too...
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
When you replaced the hoses, did you do one at a time? If not, check the routing.

If it did run properly for a day, check the hoses to see if one came off the n75 or actuator.

Do you have VCDS? If so, you can test the vnt system.
 

Rhh

Member
Joined
Feb 24, 2014
Location
Vancouver
TDI
02 Jetta
Thanks for the reply....

Yes, one hose at a time,

The routing is exact as per the diagram in the thread (same one in my OEM shop manual)

The hoses are all secure and fit well.

I checked the n75 and actuator hoses and all of them are connected properly.

I just pulled the exhaust pipe off of the left side of the turbo to test the shaft for any play (there is no play, and there is also smooth free movement of the turbine blades).

I've heard that worn bearings can result in the shaft wearing out and oil leaking into the turbines, (I assume just on the intake side?). I took pictures of both sides of the turbo, the exhaust side is free of oil but the side feeding to the intake appears to have oil on the outside of the hoses. I'm not sure where it comes from.

Can anyone tell me if this is a sign of an internal oil leak within a turbo. There is oil above (gravity) these hoses and I assume the leak was the same vacuum pump oil leak I fixed previously. (The exhaust side of the turbo is better sheltered in its location and didn't get leaked on???)

Thanks again.
Rob
 
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