BEW power loss on hills, emergency bandaid fixes?

Nuje

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Island near Vancouver
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2002 Golf 6MT; 2015 Sportwagen 6MT; 2016 A3 e-tron 6DSG
With VCDS, you can log MB 11 and watch the boost level and see what happens to it when the power drops - should go from like ~2000kpa to suddenly around 1000kpa.

(Important note: the following is how you check on an ALH; not sure if it all applies to the BEW, but I'm pretty sure it does.)
To check the vanes, gotta get under the car and with VCDS, you can use BASIC SETTINGS or OUTPUT TESTS or maybe ADAPTATIONS (sorry - can't remember), to check "charge pressure control". The car then cycles between turbo "on" and "off", with vacuum "pressure" pulling actuator arm. You have to go under the car and look at it - should move super-smoothly in both directions; if there's any stuttering - that's the vanes sticking.

Also connect a MityVac to the vacuum line going to the turbo and see if it holds vacuum - pump it up to 20"Hg and it should hold there for half a minute at least without budging. If it starts dropping, either there's a hole in the vacuum line or the actuator is faulty.

Edit: Probably better explanation of the OUTPUT TESTS here:
 
Last edited:

watatrp

Veteran Member
Joined
Feb 29, 2008
Location
South Bend, IN
TDI
04 Jetta tdi (gone) 2013 Passat SEL TDI
Just some possibilities. Friend of mine had a BEW with similar behavior. His intake was clogged w/ carbon build up. Mine did the same but ended up being a worn out cam. One of the lifters had a hole in it too. Easy to check with a look under the cover.
 

tdwesty

Veteran Member
Joined
Nov 9, 2009
Location
Vancouver Island, BC, Canada
TDI
'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
Just some possibilities. Friend of mine had a BEW with similar behavior. His intake was clogged w/ carbon build up. Mine did the same but ended up being a worn out cam. One of the lifters had a hole in it too. Easy to check with a look under the cover.
Thanks for the info. I plan to check the cam as I haven't looked under the cover for >10 years or about 200k kms. Running T6 or Motul 8100 so hoping it is ok.
 

tdwesty

Veteran Member
Joined
Nov 9, 2009
Location
Vancouver Island, BC, Canada
TDI
'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
With VCDS, you can log MB 11 and watch the boost level and see what happens to it when the power drops - should go from like ~2000kpa to suddenly around 1000kpa.

(Important note: the following is how you check on an ALH; not sure if it all applies to the BEW, but I'm pretty sure it does.)
To check the vanes, gotta get under the car and with VCDS, you can use BASIC SETTINGS or OUTPUT TESTS or maybe ADAPTATIONS (sorry - can't remember), to check "charge pressure control". The car then cycles between turbo "on" and "off", with vacuum "pressure" pulling actuator arm. You have to go under the car and look at it - should move super-smoothly in both directions; if there's any stuttering - that's the vanes sticking.

Also connect a MityVac to the vacuum line going to the turbo and see if it holds vacuum - pump it up to 20"Hg and it should hold there for half a minute at least without budging. If it starts dropping, either there's a hole in the vacuum line or the actuator is faulty.

Edit: Probably better explanation of the OUTPUT TESTS here:
Thanks, I got the old laptop going and found the following codes. I'm guessing the O2 sensor too rich is related to a sudden drop in boost.

16618 - Boost Pressure Regulation
P0234 - 000 - Limit Exceeded (Overboost Condition)
Freeze Frame:
RPM: 2268 /min
Torque: 272.0 Nm
Speed: 101.0 km/h
Load: 83.5 %
Voltage: 13.91 V
Bin. Bits: 00101000
Absolute Pres.: 1968.6 mbar
Absolute Pres.: 2560.2 mbar

18628 - Oxygen (Lambda) Sensor B1 S1
P2196 - 000 - Signal too High (Rich)
Freeze Frame:
RPM: 2268 /min
Torque: 0.0 Nm
Speed: 103.0 km/h
(no units): 255.0
Temperature: 19.8°C
Absolute Pres.: 969.0 mbar
Voltage: 1.825 V
Lambda: 5.3 %

Readiness: 0 0 0 0 0

Also, the same old coolant sensor error which has been going on for years.

01039 - Coolant Temperature Sensor (G2)
30-10 - Open or Short to Plus - Intermittent

I will attempt to perform the actuator tests now that I have VAGCOM running again.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Had to go back and read Post#1. So it's low power possibly limp mode. Have you checked underneath to see all the big pipes are snug?
Also the AC ain't right. This could be the CTS, likely unrelated to the power issue.
 

tdwesty

Veteran Member
Joined
Nov 9, 2009
Location
Vancouver Island, BC, Canada
TDI
'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
Had to go back and read Post#1. So it's low power possibly limp mode. Have you checked underneath to see all the big pipes are snug?
Also the AC ain't right. This could be the CTS, likely unrelated to the power issue.
The big pipes look ok, but I did have an issue with the circlip popping off on the pipe at the intake, and drilled a small screw to hold it in place last year. I will take a good look at them again.

I just ran the N75 boost pressure test, and it cycled every 5 seconds from 980 mbar to 1120mbar consistently. Also the EGR test on the same page seemed normal. Next I will get a camera under there to observe the actuator to see if it is moving full travel or not. And I will finish reading the N75 thread linked above to see if there are more clues there.
Of course, still need to remove the valve cover to look at the cam & lifters, but really hope it's not that, as I don't have time to deal with a new cam.
 

Nuje

Top Post Dawg
Joined
Feb 11, 2005
Location
Island near Vancouver
TDI
2002 Golf 6MT; 2015 Sportwagen 6MT; 2016 A3 e-tron 6DSG
I did have an issue with the circlip popping off on the pipe at the intake, and drilled a small screw to hold it in place last year
Is that all sealed properly? No oily accumulation there? Did you replace the o-ring on that connection as well?
I might have a "doggie collar" for that joint in the garage here to hold it a little more properly, as a screw will only hold it at one point, whereas the "doggie collar" clamps down roughly 180° of the circumference.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
The actuator on the PD has an electrical component as well.
Many issues on these aging TDIs are wires/connects
 

tdwesty

Veteran Member
Joined
Nov 9, 2009
Location
Vancouver Island, BC, Canada
TDI
'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
I checked the intercooler pipes and there is definitely a bit of oil at the I/C and the intake junctions, so I am due for new o-rings. (anyone have a source online in Canada?)
The screw I had added to secure the pipe at the intake manifold had come loose, so that may explain my problem. For now, I replaced the self tapping screw with a larger size and tapped new threads to make it more secure. The reason for this screw is that the retaining tabs on the hose collar which the circlip catches on are worn right down. I will plan to replace this hose assembly.
The N75 test worked perfectly several times, and an inspection camera on the actuator showed fairly smooth and quick movement (I think) (see video here)
I also checked the cam and lifters, and could see no signs of excessive wear, although I didn't rotate it to check all the lobes, but those I could see showed the chamfer on the lobe still intact.
I'm hoping it's just the leaky I/C pipes/hoses, since it seems to take a significant period of high boost to trigger a limp mode. For example, the last trip we made over the Coq and back was without incident, and it wasn't until day 3 of our trip to Cali that limp mode occurred. I just remembered, that was also after filling up with B99 bio-D, which was all they had where we stopped. Not sure if this could have any effect.
 

Tdijarhead

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Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
Here is what the “dog collar” looks like. Possibly someone in Canada has one, I’ve had a dog collar on my car for 10 years or so, they work perfect.


The 3 thin wires leading to the vacuum actuator which controls the turbo will get old and compromised. They will need repair at some point, when mine went bad my turbo wouldn’t work.
 

PakProtector

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Joined
Jan 5, 2014
Location
AnnArbor, MI
TDI
Mk.4's and the Cummins
The actuator on the PD has an electrical component as well.
Many issues on these aging TDIs are wires/connects
My latest acquisition( a year ago now), had its smart actuator wires worn thru by the protective armor sleeve. I cut them back to good copper and spliced in a new connector. The low power went away. This at 53k miles. It will get an actuator-free tune at some point so I am un-worried long term...LOL

Douglas
 

tdwesty

Veteran Member
Joined
Nov 9, 2009
Location
Vancouver Island, BC, Canada
TDI
'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
My latest acquisition( a year ago now), had its smart actuator wires worn thru by the protective armor sleeve. I cut them back to good copper and spliced in a new connector. The low power went away. This at 53k miles. It will get an actuator-free tune at some point so I am un-worried long term...LOL

Douglas
I'm at 389k kms, and the actuator does seem to be working ok. What do you mean by an actuator-free tune?
 

tdwesty

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Joined
Nov 9, 2009
Location
Vancouver Island, BC, Canada
TDI
'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
Here is what the “dog collar” looks like. Possibly someone in Canada has one, I’ve had a dog collar on my car for 10 years or so, they work perfect.


The 3 thin wires leading to the vacuum actuator which controls the turbo will get old and compromised. They will need repair at some point, when mine went bad my turbo wouldn’t work.
Thanks, I should be able to fabricate something like that. Or I could just add another screw on the other side for now.
 

P2B

Top Post Dawg
Joined
Jan 11, 2006
Location
Toronto & Muskoka, Canada
TDI
2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
I'm at 389k kms, and the actuator does seem to be working ok. What do you mean by an actuator-free tune?
Your actuator movement looks fine in the video. No such thing as an actuator free tune, he probably means one that doesn't use input from the actuator position sensor.
 

tdwesty

Veteran Member
Joined
Nov 9, 2009
Location
Vancouver Island, BC, Canada
TDI
'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
Your actuator movement looks fine in the video. No such thing as an actuator free tune, he probably means one that doesn't use input from the actuator position sensor.
Thanks. After reading a thread on all the things that can go wrong with replacing the coolant temp sensor, I'm going to leave it alone. I can't risk breaking anything else right now, and it doesn't leak. I still suspect I may have a partially stuck open thermostat, as it takes a long time to get heat (but that's another job with a high risk of screwing something up...).
The flaky gauge isn't affecting anything as far as I can tell. It's been like this for >10 years, although lately the gauge mostly works, just reads low most of the time, like 60-70C, then climbs to 80-90 on hills. So if it's accurate, it seems like a bad t-stat. Mu '03 ALH wagon heats up much faster and produces much more heat than the BEW ever does, which is another clue that the t-stat may be stuck.
 

northern diesel

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Joined
Dec 5, 2023
Location
Northern BC
TDI
2006 mk4 TDI Jetta Wagon
Thanks. After reading a thread on all the things that can go wrong with replacing the coolant temp sensor, I'm going to leave it alone. I can't risk breaking anything else right now, and it doesn't leak. I still suspect I may have a partially stuck open thermostat, as it takes a long time to get heat (but that's another job with a high risk of screwing something up...).
The flaky gauge isn't affecting anything as far as I can tell. It's been like this for >10 years, although lately the gauge mostly works, just reads low most of the time, like 60-70C, then climbs to 80-90 on hills. So if it's accurate, it seems like a bad t-stat. Mu '03 ALH wagon heats up much faster and produces much more heat than the BEW ever does, which is another clue that the t-stat may be stuck.
What about replacing your Tstat?
I remember @burpod telling me to replace mine when I was getting coolant temp sensors readings that made no sense.
I spent time doing almost all of what you are to resolve overboost and underboost issues.
I removed the intake manifold for a good clean- replaced vac lines / N75 valve (although sounds like yours is good).
Burpod also de-tuned the “smart actuator” on my BEW, it now actuates using vacuum and engine readings only like @PakProtector was mentioning.
Charge pipes with tiny leaks might be your culprit
 

tdwesty

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Joined
Nov 9, 2009
Location
Vancouver Island, BC, Canada
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'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
It may be the t-stat, but changing the sensor is easier. In any case, I may need to make the same drive south next week, so I'm not about to mess with anything right now that could throw a wrench in things. I have re-secured the intake hose and will hope for the best. The car ran flawlessly aside from limp mode a few times, which is something we can deal with. Sadly, after the unintended dance with an F150 on the interstate, I am less inclined to put more into this car, as it is now pretty sad looking, one fender rusted (accident from PO with a crappy aftermarket fender), and the other fender flattened. :(
 

tdwesty

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Joined
Nov 9, 2009
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Vancouver Island, BC, Canada
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'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
It looks like I can get new fenders for about $125 each, but the hard part will be finding a shop to paint them at a reasonable price. If the car survives the next trip, I'll look into treating her to some new body parts. Any leads on a budget paint option near Victoria, BC?
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
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2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
I bought a new aftermarket prepainted fender off eBay the color match was perfect.

 

PakProtector

Top Post Dawg
Joined
Jan 5, 2014
Location
AnnArbor, MI
TDI
Mk.4's and the Cummins
I'm at 389k kms, and the actuator does seem to be working ok. What do you mean by an actuator-free tune?
The BEW has a position sensor in the actuator. And I mis-spoke a bit; I meant a smart actuator tune( one that does not look for the position-sensor feedback ). The wires to that position sensor were open on that young '05 car and it ran low on power and turbo response( the turbo is a KP39 and when everything is working OK, is near instant ).

There were codes for that sensor though, and they tripped the CEL on the dash too. You seem to be missing those.

Douglas
 

tdwesty

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Joined
Nov 9, 2009
Location
Vancouver Island, BC, Canada
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'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
The BEW has a position sensor in the actuator. And I mis-spoke a bit; I meant a smart actuator tune( one that does not look for the position-sensor feedback ). The wires to that position sensor were open on that young '05 car and it ran low on power and turbo response( the turbo is a KP39 and when everything is working OK, is near instant ).

There were codes for that sensor though, and they tripped the CEL on the dash too. You seem to be missing those.

Douglas
Thanks for the info. The car definitely has less power than it did when we bought it at 190K, but I think it has been a gradual loss. I test drove a 2005 BEW wagon with 190K recently, and was reminded what the power used to be like... but that car also left a huge cloud of black smoke when I floored it in second gear, something mine has never done, so I wondered if it had been altered somehow.
My VCDS mentions Garrett, so I assume that is the turbo that I have, but I really haven't checked. It has enough power for my needs, as long as it stays out of limp mode. Will try to find a long enough hill to trigger it today, but it's hard to test around here with max speed limit of 90km/h.
 

PakProtector

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Joined
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Location
AnnArbor, MI
TDI
Mk.4's and the Cummins
These things should not smoke. However, I once got a 1st Gen Cummmins cloud out of my '04 on an idle-to-3500 rpm pull in second. Inky, black stuff on a stock engine/ecu. Only once.

Douglas
 

tdwesty

Veteran Member
Joined
Nov 9, 2009
Location
Vancouver Island, BC, Canada
TDI
'04 Jetta TDI 5sp, '03 Jetta TDI Wagon Auto
These things should not smoke. However, I once got a 1st Gen Cummmins cloud out of my '04 on an idle-to-3500 rpm pull in second. Inky, black stuff on a stock engine/ecu. Only once.

Douglas
Yes, I've never seen any significant smoke from our BEW. The ALH wagon however can produce a fair bit of smoke when pressed, although not to LDS pickup truck levels.
 

ExBenz

Member
Joined
May 11, 2015
Location
Evansville, Indiana
TDI
'04 Golf
Try this:

Unplug the MAF sensor sometime and see if the cruise control holds speed better. Usually when it goes into limp mode from a bad MAF you get an EGR flow error though but before complete failure it can cause a number of symptoms, one of which is low boost and another is failure to hold speed on hills using cruise. Probably fails to increase boost properly.

Definitely replace the coolant temp sensor AND the thermostat after verifying actual engine temp. If you are showing low coolant temp on the gauge it's likely very low in the engine, that gauge reading is "interpreted" by the ECU, it's not actual engine temp. Will read 90C rock steady between about 80C and 120C. Engine (and heater) temp drift around on these cars because they produce so little waste heat at idle and low speed and VW decided to protect us from stress for some reason. At any rate, consistent reading of 60C in moderate traffic means the thermostat isn't closing or the temp sensor is bad.

Finally, check the condition of the vacuum line from the dual pump to the brake booster. All the vac for turbo control and EGR comes off that main line at the check valve on a small T, and if the mail like is cracked (and they all do, it's shrink fit plastic) you will have a hard brake pedal, erratic boost, and improper EGR operation. Bad boost control switchover valves can also cause trouble, I've replaced more than a couple of them.

Low temp (or bad temp sensor) wont' run the engine correctly, it will be in cold operation mode all the time (late injection timing for instance).
 
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