2004 TDI Limp Mode Help

[Wandersk]

Hey all. Apologies in advance for the long-winded post, I have some history with this car. Bought my '04 back in 2010. Ran great on the test drive, went into limp mode on the first real drive. Not knowing much about diesels, or this site , took it to an import shop and they replaced turbo. Still went into limp mode, took it back and they said I wrecked the turbo again and need to replace it again, NOPE! I got it scanned and was getting overboost code. Besides going into limp mode it ran fine and I only drove it a few miles a day to work and back so I just ignored the problem, for years. A couple years ago it started dying randomly so I parked it in the boneyard. Now that fuel is crazy I have pulled it out and hope to turn it into my road trip car. First thing I did was go through the turbo lines, found a leak and replaced line. This eliminated the boost codes, but still going into limp mode and dying randomly. Was getting multiple codes. P0726, P0725, P2637, P2108, P2564. Thanks to this forum I was able to rectify the dying issue and codes 0726, 0725, 2637 by replacing the crank speed sensor. Now I'm back to square one, but without any boost codes. Just P2108 and P2564. I know I'll be told to invest in vcds but the funds aren't available at the moment. As far as I can tell P2108 is related to the anti-shudder valve and P2564 is the turbo actuator sensor. I checked the wiring at the actuator sensor end, seems fine. Next step was to check the wires at the ECU end, but my research on here is telling me neither of these codes should cause limp mode. I know I still need to deal with both codes, but am I barking up the wrong tree as far as keeping this baby out of limp mode? If neither of these codes should cause limp mode, why am I getting no other codes such as over/under boost? Just because I'm not using vcds? Any help would be much appreciated! Also if there is anyone in southeast Sask with vcds I would love to meet up!

 

[drucifer]

If you haven't gone through canadian grizzly's limp mode thread now would be a good while waiting for others

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

Diagnosing and Fixing Limp mode for A4 1.9TDI By Canadian Grizzly Read the entire post prior to jumping to conclusions. This is a general overview on how to diagnose and fix a A4 1.9TDI that goes into “limp” mode due to an overboost of the turbo. While I’m by no means an expert I’ve gleaned...

forums.tdiclub.com

 

[Wandersk]

If you haven't gone through canadian grizzly's limp mode thread now would be a good while waiting for others

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

Diagnosing and Fixing Limp mode for A4 1.9TDI By Canadian Grizzly Read the entire post prior to jumping to conclusions. This is a general overview on how to diagnose and fix a A4 1.9TDI that goes into “limp” mode due to an overboost of the turbo. While I’m by no means an expert I’ve gleaned...

forums.tdiclub.com

Hey drucifer, I have gone through this but it suggests limp mode is being caused by an overboost issue, so I'm confused why I'm not getting any boost related cel codes. Thinking I need vsds to really apply grizzly's thread to my issue...

 

[oilhammer]

Your definition of limp mode may not even be correct, really tough to say. You can unplug the throttle flap, which defaults to wide open, and unplug the EGR valve, which defaults to closed, and you can drive the car all over the place and it will run OK and not stall or experience reduced power.

Assuming you have the correct (non-Chinese) turbo on there, and the vane sensor itself is not bad, then I'd pull the wire cover back from the vane sensor all the way to where it goes into the harness up under the cowl and make certain it is good.

 

[Wandersk]

Your definition of limp mode may not even be correct, really tough to say. You can unplug the throttle flap, which defaults to wide open, and unplug the EGR valve, which defaults to closed, and you can drive the car all over the place and it will run OK and not stall or experience reduced power.

Assuming you have the correct (non-Chinese) turbo on there, and the vane sensor itself is not bad, then I'd pull the wire cover back from the vane sensor all the way to where it goes into the harness up under the cowl and make certain it is good.

By limp mode I mean my turbo kicks out, I can still get up to highway speed very slowly but if I turn the car off then back on I get turbo again and life is good for the next 10 minutes or so. I plan on checking the wire out all the way up tonight. I am just concerned that users have said in other threads that this faulty wiring or sensor shouldn't cause limp mode.

 

[oilhammer]

Well, again, you are making an assumption. "Turbo kicking out"... you know this how? You have not watched the actual vs. requested boost via a suitable scan tool, have you? It may be more of "reduced power mode" and you (we) don't really know WHY the ECU is doing this. That's what the shop that installed a turbo did... jumped to a false conclusion without proper diagnosis.

 

[drucifer]

As long as you have a serial port laptop the price of a tank and a half of fuel will get you vcds.

FS: genuine Ross-Tech interfaces

Ross-tech micro-can interfaces $195 plus shipping. For 2006+ cars with can network. Ross-tech hex-v2 three vins SOLD shipped in the USA

forums.tdiclub.com

 

[Wandersk]

Well, again, you are making an assumption. "Turbo kicking out"... you know this how? You have not watched the actual vs. requested boost via a suitable scan tool, have you? It may be more of "reduced power mode" and you (we) don't really know WHY the ECU is doing this. That's what the shop that installed a turbo did... jumped to a false conclusion without proper diagnosis.

I see what you're saying. I just assumed it was limp mode based on researching other posts and users with the same description of limp mode, never thought that "reduced power mode" would match the same symptoms. Either way I'm not getting any codes that should trigger these reduced power issues. Looks like I'll need to invest in vcds to go any further. Thanks.

 

[Wandersk]

As long as you have a serial port laptop the price of a tank and a half of fuel will get you vcds.

FS: genuine Ross-Tech interfaces

Ross-tech micro-can interfaces $195 plus shipping. For 2006+ cars with can network. Ross-tech hex-v2 three vins SOLD shipped in the USA

forums.tdiclub.com

Unfortunately I don't have a laptop so it will be a bigger investment than just a cable plus shipping for me, but looks to be inevitable if I want to get this thing running properly.

 

[Vince Waldon]

(Unfortunately) it's not uncommon for no codes to be present, even though the ECU is clearly upset about something. On-board diagnostics were pretty rudimentry back in 2004.

The ECU can be upset about overboost or underboost... basically any time the turbo is NOT doing what the ECU is commanding. So, distinguishing between an overboost "limp mode" or an underboost "limp mode" is sometimes a bit of a red herring... the point is, the ECU thinks it has lost control of the turbo and shuts stuff off to avoid potential damage.

And yup, diagnosing something that's making the ECU unhappy without the tool that shows you what the ECU is seeing and (somewhat) thinking is tricky... VCDS is pretty much as important in the tool kit as the 10/13/17mm sockets and wrenches.

Any el-cheapo laptop off Craigslist will do BTW, very little horsepower or memory are required.

 

[J_dude]

Where in Sask are you? I have VCDS

 

[Wandersk]

Where in Sask are you? I have VCDS

Southeast. Estevan area.

 

[Wandersk]

(Unfortunately) it's not uncommon for no codes to be present, even though the ECU is clearly upset about something. On-board diagnostics were pretty rudimentry back in 2004.

The ECU can be upset about overboost or underboost... basically any time the turbo is NOT doing what the ECU is commanding. So, distinguishing between an overboost "limp mode" or an underboost "limp mode" is sometimes a bit of a red herring... the point is, the ECU thinks it has lost control of the turbo and shuts stuff off to avoid potential damage.

And yup, diagnosing something that's making the ECU unhappy without the tool that shows you what the ECU is seeing and (somewhat) thinking is tricky... VCDS is pretty much as important in the tool kit as the 10/13/17mm sockets and wrenches.

Any el-cheapo laptop off Craigslist will do BTW, very little horsepower or memory are required.

I hear ya. At least when I had the bad hose I was getting boost codes. Now I'm flying blind haha

 

[J_dude]

Southeast. Estevan area.

Dang, I travel a lot but I don’t get out that way much, I’m about an hour and a half southwest of Swift.

 

[Wandersk]

Update : I checked out the wiring at the actuator sensor again and did find a small fray on 2 of the wires. Don't have materials to splice so I just taped them up good for now. All codes cleared with my crappy code reader this time (even the cyl 3 glow plug which is strange) so I went for a drive. After about 10 minutes of normal driving I pulled over to check my tail lights. When I got back in cel was on and limp mode/reduced power mode struck again. 2 codes came up, P2108 which I think is the anti-shudder valve and P2637 is back, Torque Management Feedback Signal A. Turned car off and back on to restore power and it drove fine the 10 minutes back home. Frustrated that I'm getting a partially painted picture without VCDS I just started looking at all sensors/connections and came across a connection just behind the fan on the battery side that has 1 of 4 wires completely broken off. Can't really trace it as it harnesses in with more wires in both directions but does anyone know what this could be? I can't figure out how to post a picture on here. Not getting my hopes up that this is my whole issue but damn it's gotta be something.

 

[Wandersk]

https://ibb.co/3yChz3shttps://ibb.co/fGW1xrK

Hope this works, links to the pictures of the connection I'm talking about.

 

[Tdijarhead]

I saw your pic, that needs to be fixed obviously, it is likely the cause of the two codes that keep cropping up. P2108. P2637

If you taped up the wires to your actuator and it helped with the cars boost problem but didn’t eliminate it I would revisit those wires and repair them properly. My 05 was going into limp mode when those actuator wires were damaged on my car, repairing them solved my issue.

 

[oilhammer]

As I noted in a different thread, the Jatco cars have an extremely cramped wire harness area near/under the battery. So wire issues in that section are common.

 

[Wandersk]

I saw your pic, that needs to be fixed obviously, it is likely the cause of the two codes that keep cropping up. P2108. P2637

If you taped up the wires to your actuator and it helped with the cars boost problem but didn’t eliminate it I would revisit those wires and repair them properly. My 05 was going into limp mode when those actuator wires were damaged on my car, repairing them solved my issue.

I'll definitely still properly fix the wires but taping them stopped the sensor code from coming up. Without vcds I'm nor sure if I'm even having a boost problem at all or if this newly locates wire break is causing the reduced power issue. This wire is broken right where it goes into the connector and of course there is no room to work there at all, so fixing is going to be extremely challenging.

 

[oilhammer]

Plenty of room if you put the lock carrier in service position (or even better, just take the whole thing off):

 

[Wandersk]

As I noted in a different thread, the Jatco cars have an extremely cramped wire harness area near/under the battery. So wire issues in that section are common.

Extremely cramped for sure. And electrical work isn't my best skill. With it being broken right at the connector, any recommendations for fixing it? I've been trying to source a repair video for a similar break. I might have to just cut all the wires and add a foot or so to all of them so I have room to pull the connector out to work.

 

[Wandersk]

Plenty of room if you put the lock carrier in service position (or even better, just take the whole thing off):

Oh wow, that would be ideal but I'm afraid I might not be up for that challenge without causing more issues.

 

[BobnOH]

.....snip............... , took it to an import shop and they replaced turbo. Still went into limp mode, took it back and they said I wrecked the turbo again and need to replace it again,.....snip...............

God damn those people, they go right for the most expensive bit.
Limp mode and low power are very similar and share many of the same solutions.
If I had to interweb guess, I'd say the actuator is not actuating properly. Good chance it's wires/connects. Very common on 20 year old TDIs.

 

[Wandersk]

Update : Thanks for the help everyone. I'm still not sure where those broken wires by the fan were going, but I soldered them up and the car has been running great ever since. 3 mechanics, 1 turbo, and 12 years later all it took was a little help from TDIClub!