'04 Sir Limps A Lot; the saga continues

PickleRick

Veteran Member
Joined
Nov 29, 2017
Location
Greenville sc
TDI
05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
No. I can't afford a 1st gen 4 runner turbo model...nor would I want a gas powered sub.

I'll be using an ebay intercooler. You can buy an adapter that replaced the anti shutter valve that adapts the intake to a standard turbo silicone elbow, held on with trusty t bolt hose clamps.
 

Zeitgeist

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Joined
Nov 10, 2004
Location
Cascadia
TDI
'04 Variant and Vanagon mTDI
Alright, I'm officially at my wits' end. My last hail mary play here was to replace the vacuum pump. This briefly allowed me to drive to and through my favorite limp triggering sections of road, which buoyed my hopes enough to think we could drive the car thirty miles out of town tomorrow. Sadly, subsequent trips earned a limp mode randomly on the highway for no apparent reason. I honestly don't know what else to do at this point. There are no external boost leaks, and the turbo is fairly new and recently cleaned. It has a new MAF, MAP, N75 and vacuum pump. There's no anti-shudder valve or EGR valve to contend with, so I'm now wondering if the ECU is defective. Did I mention that I hate limp mode?
 

Zeitgeist

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Joined
Nov 10, 2004
Location
Cascadia
TDI
'04 Variant and Vanagon mTDI
I'll post this here since it addresses the issues I've been having. I've investigated everything except #2 mis-adjusted VNT actuator.

I'll give that a try next. I drove the car all around town today, up hills as well as full throttle acceleration runs, without triggering Limpy McJohnson's sad trombone. ***?
 

QuickTD

Veteran Member
Joined
Feb 25, 2002
Location
SW Ontario
TDI
2003 Audi A4Q 5spd 2.0 TDI 2056VK R783, 2006 Audi A4Q 6spd 2.0 TDI, 2007 A4Q 6spd 2.0 TDI
Looking at your pics, I would start the diagnosis by putting the car back to stock config. With no EGR and no delete tune, you will have all sorts of problems, mostly related to boost and mass airflow. You can't just remove emissions equipment and hope that it works. The OEM tune is looking for that stuff.
 

Zeitgeist

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Joined
Nov 10, 2004
Location
Cascadia
TDI
'04 Variant and Vanagon mTDI
All of these conditions existed before I pulled those items. In fact, it runs much much better now, but it still goes randomly into limp mode. It used to go into limp mode in exactly the same places on hills or load runs around town prior to removing the offending items. I have a long history with EGR causing more problems than it solves with turbodiesels. I plan on getting a tune for this ECU which will eliminate the EGR and anti-shudder valve, but don't want to make this investment if the ECU is faulty.
 

QuickTD

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Joined
Feb 25, 2002
Location
SW Ontario
TDI
2003 Audi A4Q 5spd 2.0 TDI 2056VK R783, 2006 Audi A4Q 6spd 2.0 TDI, 2007 A4Q 6spd 2.0 TDI
The ECU is not faulty. If it is I'll send you one for free, tuned how you like. I have them stacked like cordwood here, they are unsellable because they do not fail.

Have you looked at the most basic items? Leave car overnight, check temp sensors, air, fuel and coolant, do they agree? Check boost pressure and ambient pressure with key on engine off. Do they agree? Mass airflow you cannot check due to your hillbilly EGR delete, boost commanded vs actual will also be out to lunch at cruising speed due to same, and could very well be the source of the issue. You may well have fixed the problem, but running stock mapping with a blocked EGR you will never know. These are the reasons I will not tune a car with the engine light on.

Have you checked that the N75 and CCV heater plugs are not transposed? That will get you an overboost code as soon as you step on the accelerator, and set no other codes in the process.
 

Zeitgeist

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Nov 10, 2004
Location
Cascadia
TDI
'04 Variant and Vanagon mTDI
That's good to know about the robustness of the ECUs. I agree that I should be checking the parameters of various sensors and whatnot, if only I had a BHW or even a BEW manual. I assume the CCV pigtail is the shorter of the two. I have all the bits n' bobs I've removed from the engine, and can return everything to stock...as a last resort. I removed those items as much for accessibility as the desire to eliminate unsightly and unwanted weight. I really like the longitudinal arrangement for its relative ease of service as opposed to transverse, and I like furthering that goal as much as possible. Moving the N75 is probably my favorite mod.
 

QuickTD

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Joined
Feb 25, 2002
Location
SW Ontario
TDI
2003 Audi A4Q 5spd 2.0 TDI 2056VK R783, 2006 Audi A4Q 6spd 2.0 TDI, 2007 A4Q 6spd 2.0 TDI
N75 wires are red/white and brown/yellow. CCV heater is red/green and brown. I wouldn't say a manual is necessary, I've never owned one and I somehow manage to stuff lots of these BHW things into places they were never meant to go, into audi's mostly. First thing on my agenda is always to get the CEL out though, then maybe start ditching parts. I find it goes better that way. I always leave the EGR functional, I like the quieter engine at cruise and it slams shut as soon as you tip into the accelerator, so performance is unaffected. The cooler also provides heat, and it gets cold here. Same day warmup is a plus.

Pic of one of my BHW ECU "stacks" for grins, there are a bunch more around here somewhere... :)

 

borninabus

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Feb 18, 2020
Location
Arizona
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B5.5 Passat Wagon: RIP Chief Boy :-( 2013 JSW 6MT
i mentioned this before and maybe you've already crossed this bridge, but is your torque converter locking up like it should?
 

zzdiesel

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Joined
Dec 10, 2010
Location
sask. mostly now Wa.
TDI
05 passat tdi Geared BSM and Bewcam 2nd 2005 deleted ,converted and bew cam stage 2 Malone3 tune.
Why do you have these ECUs. If you are stuffing a BHW into another vehicle do you not need an ECU to control the engine?
 

QuickTD

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Feb 25, 2002
Location
SW Ontario
TDI
2003 Audi A4Q 5spd 2.0 TDI 2056VK R783, 2006 Audi A4Q 6spd 2.0 TDI, 2007 A4Q 6spd 2.0 TDI
I stuff BHW's into audi A4's. I import ECU's from european A4's that play nice with the audi's electronics. The passat ECU does not have the hardware for bus-based cruise control switches and variable speed PWM controlled cooling fan. Some people have told me that the ECU can be modified, but the euro ECU's are very cheap. I don't think I've paid more than $50 for one.
 

Zeitgeist

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Joined
Nov 10, 2004
Location
Cascadia
TDI
'04 Variant and Vanagon mTDI
Man, an AWD TDI sure would be sweet. Our old C4 Avant was absolutely unstoppable in the snow, especially with the locking rear diff. I always wanted to source a Euro AEL to swap in for the anemic V6 we got here.
 

Zeitgeist

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Nov 10, 2004
Location
Cascadia
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'04 Variant and Vanagon mTDI
i mentioned this before and maybe you've already crossed this bridge, but is your torque converter locking up like it should?
I'm not entirely sure if it is or not. I have no frame of reference to use as a good guide. The power delivery often feels uneven, which could be the TC slipping I guess. I don't get any TCU faults, except for an occasional gear selector implausible or something like that.
 

borninabus

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Joined
Feb 18, 2020
Location
Arizona
TDI
B5.5 Passat Wagon: RIP Chief Boy :-( 2013 JSW 6MT
pay me some shipping and i'll send you a TCU :)

you know there are some grounds and factory splices to look at, right?
any moisture under the carpets?
TCU and loom are on the passenger side.
down the outside of the footwell and the unit is under the seat. you should investigate!

it's been a while since i've been behind the wheel of a B5, but the the RPMs shouldn't flair...if you know what i mean. should respond like a MT most of the time except under light loads. i seem to remember "mozambiquer" dealing with this and a solution.

just MT swap the thing already!
 

Mozambiquer

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Mar 21, 2015
Location
Versailles Missouri
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1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI
pay me some shipping and i'll send you a TCU :)

you know there are some grounds and factory splices to look at, right?
any moisture under the carpets?
TCU and loom are on the passenger side.
down the outside of the footwell and the unit is under the seat. you should investigate!

it's been a while since i've been behind the wheel of a B5, but the the RPMs shouldn't flair...if you know what i mean. should respond like a MT most of the time except under light loads. i seem to remember "mozambiquer" dealing with this and a solution.

just MT swap the thing already!
Yup, I dealt with that, all the way out in the outer banks... My TCM was internally shorted, but water intrusion is also a common issue.
 

Zeitgeist

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Nov 10, 2004
Location
Cascadia
TDI
'04 Variant and Vanagon mTDI
I pulled the passenger carpet today and found some moisture down there, but zero evidence of moisture entering the TCU case. Where are the grounds I should be checking located?
 

Mozambiquer

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Mar 21, 2015
Location
Versailles Missouri
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1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI
I pulled the passenger carpet today and found some moisture down there, but zero evidence of moisture entering the TCU case. Where are the grounds I should be checking located?
In the harness just before the TCM (i don't remember if it's before the box or inside the box) there is a ground wire splice that some cars had problems with. There's maybe 4 wires that come together, they're brown, if I recall. You'll unwrap that and solder them and then tape them back up.
 

Zeitgeist

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Location
Cascadia
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'04 Variant and Vanagon mTDI
The more I think about it, I'm now thinking that a toggle switch to reset the ECU whenever it goes into limp mode makes the most sense. At least I'd have an idea that something in the parameters was amiss. But, I could reset on the fly without having to pull over, put the trans into park, turn off the key, and then turn it back on.

Invariably the car goes into limp mode on a hill with no shoulders and a super pissed off milkman in my rearview. Countless true crime novels are written with that scenario as an opening. I don't want to become a statistic.

 
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QuickTD

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Feb 25, 2002
Location
SW Ontario
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2003 Audi A4Q 5spd 2.0 TDI 2056VK R783, 2006 Audi A4Q 6spd 2.0 TDI, 2007 A4Q 6spd 2.0 TDI
Have you sat down with VCDS and comprehensively looked at things? I may have missed something, but I don't recall seeing any of that here. Have you run the most basic first line diagnostic test for over/underboost codes (basic settings group 11) to see if the charge pressure controls system works at all? Have you compared temp sensor readings with a cold engine? Compared barometric to manifold pressure with key on engine off? Do a brake torque and listen for boost leaks? Seems like your efforts have concentrated mostly on ripping stuff off the engine and hoping for the best. I don't feel that approach is a sound method of diagnosis.

I've had lots of these cars and they all work fine, so I know its possible. I've had the occasional difficult problem but in every case a logical and methodical approach to troubleshooting has paid off. Worst limp mode case I've had was a bad MAP sensor, but set no code for it. It was off far enough in scale (about 150millibar) to set a P0101 MAF code and limp mode every single drive, but it never set a code for the MAP or boost, just MAF implausible. I found the problem by checking sensor readings against one another. I've had a BEW jetta set a light for traction control due to broken air conditioning pressure sensor wires. Unable to calculate AC drive load for traction control purposes, go figure... These are the sorts of problems that you will solve by logically looking at the data. It will literally take 10 minutes, I wish you would give it a try.
 

Zeitgeist

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Joined
Nov 10, 2004
Location
Cascadia
TDI
'04 Variant and Vanagon mTDI
Oh, I'm sure my whining is annoying for you old hands at these rigs. I get it. I too have been the grizzled veteran stuck with the sniveling noobs flailing about. I bought a very expensive VCDS mobile dongle, but still haven't figured out how to run comprehensive diagnostics. I also don't have a manual for a PD, let alone a BHW. To compound my frustration, I've found at least five issues that could easily have been the source of the boost problems, but resolving each of them did not resolve the problem. I'm an analog wrench now dealing with a digital realm, so I'm kinda trying to feel my way around, again without a proper manual which apparently doesn't exist. I pulled the antishudder valve and EGR because they were constantly in the way of my diagnostic tests, and to remove them from the list of potential variables adding to the mix. They are the only items I've removed. BTW, the EGR valve was one of the five issues I resolved, which could've been a source of underboost. The valve was all sooted up and wasn't returning to fully seat. I cleaned it and stiffened up the return spring--no fixee. I've tried to be methodical with my hardware tests, but in the absence of definitive digital diagnostics, I'm stuck with YouTube vids and annoying you guys for scraps of information.
 
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