Guru's pls help. Stuck on holiday limp mode while towing caravan

TDIFanatic1.9

Veteran Member
Joined
Jan 9, 2007
Location
South Africa
TDI
1.9 Jetta TDI
Hi There

I Scanned with vag-com and got a positive boost deviation intermitend error. Unfortunately didn't copy the error.
The limp mode only started yesterday while towing my caravan on some uphill roads. It also didn't start emediately only after a few km's of hard road. Reset by cycling ignition. On flat road only happens after a long drag and car worked hard otherwise flat road seems fine. I cannot simulate it with out the caravan and some long uphill drags. It seems to have something to do with something getting hot and sticking, when I stopped for food it cooled down and didn't happen again imediately, only again after a few km's of hard road. I checked the actuator function, it seems fine (cold engine, cannot test next to road laptop batery flty).

Please I'm towing home after 10 days and its uphill most of the way, I need the turbo to work.!!!
 

DPM

Top Post Dawg
Joined
Mar 16, 2001
Location
Newtownards, N. Ireland
TDI
2019 Rav4 AWD Hybrid, Citroen C4 BlueHDI
If the actuator is free and there's no leaky vacuum hoses, maybe try flushing the n75 valve out with some brake cleaner?
 

paramedick

TDIClub Enthusiast, Vendor
Joined
Jul 29, 2001
Location
Versailles, Kentucky
TDI
2015 Audi Q5 TDI
fault finding list.

faulty vacuum lines, sticky VNT actuator, failing N75, partially clogged intake manifold, large boost pipe not secured properly with a small leak at full boost.
 

TDIFanatic1.9

Veteran Member
Joined
Jan 9, 2007
Location
South Africa
TDI
1.9 Jetta TDI
I'll work thru the list by replacing the vac line's. The actuator I tested with vag-com and seems to move freely-dont know if it move's its whole range thou. The intake I took a peak at and its not clogged. I'm sure I'll hear a boost leak if there was any.?
Question: How do I test the N75 for functionality? Can I swap it with the egr valve, is the egr valve's response time the same as the n75?
 

jasonTDI

TDI GURU Vendor , w/Business number
Joined
Apr 26, 2001
Location
Oregon, WI
TDI
20' RAM 3500 CCLB dually HO/Aisan. 2019 Cherokee 2.0T
You can swap it. It'll work temporarily.
 

Canadian_Grizzly

Veteran Member
Joined
Apr 7, 2005
Location
British Columbia, Canada
TDI
02 Jetta TDI
Check that the vacuum line going to the actuator is not loose and falling against the block. It could be collapsing when the engine temp is high. Check my signature for the usual stuff.
 

TDIFanatic1.9

Veteran Member
Joined
Jan 9, 2007
Location
South Africa
TDI
1.9 Jetta TDI
I'm having trouble finding the correct spec and size pipe. The shops only carry fuel and oil line and only stock 3.2mm and 5mm. The pipe looks pretty firm so will probably work for vac purposes, but what to do on the 4mm hoses, can I use the 3.2 and ream out the ends to fit over the 4mm nipples?
 

dr.diesle

Veteran Member
Joined
Mar 5, 2008
Location
Calgary
TDI
92 golf tdi/01 golf tdi /02 golf tdi/04 jetta wagon tdi/vanagon westy tdi
sounds like the obvious is being overlooked stoptowing .....thats your problem get a dodge with a cummings and all will be well ....set that aside ..pull the intake boot and clean the egr valve and load up with vacum what may be happening is your boost is loosing through the egr and goes into limp mode the reason this happens under heavy load is that your ecm is used to no load its not a stored dtcso a key cycle will clear probs but its all in your dirty egr/ cooler call me crazy but it s common
 

paramedick

TDIClub Enthusiast, Vendor
Joined
Jul 29, 2001
Location
Versailles, Kentucky
TDI
2015 Audi Q5 TDI
TDIFanatic1.9 said:
I'm having trouble finding the correct spec and size pipe. The shops only carry fuel and oil line and only stock 3.2mm and 5mm. The pipe looks pretty firm so will probably work for vac purposes, but what to do on the 4mm hoses, can I use the 3.2 and ream out the ends to fit over the 4mm nipples?
Correct size for the larger vacuum lines is 5mm. Many of us use 4mm silicone for them because we can't find 5m silicone.
 

TDIFanatic1.9

Veteran Member
Joined
Jan 9, 2007
Location
South Africa
TDI
1.9 Jetta TDI
dr.diesle said:
sounds like the obvious is being overlooked stoptowing .....thats your problem get a dodge with a cummings and all will be well
Most of us can't afford 2 cars or a dedacated towing vehicle so the jetta will have to do for the od time's I get a break and go on leave. Most tows are not that far. The TDI engine produces enough torque to be a great towing engine with very good fuel returns.
 

TDIFanatic1.9

Veteran Member
Joined
Jan 9, 2007
Location
South Africa
TDI
1.9 Jetta TDI
Ok So I got home at last but I had the limp mode again even after changing the vac hoses. I then changed the n75 around with the egr valve and blocked of the egr vac hose going to the egr intake pipe as dr. diesle sugested that a stuck open egr valve might cause a los in boost through the egr. Well that sertainly made a diference as I was able to tow a lot harder and longer before the limp mode returned. It also only went limp once after about 250km of towing where it would previously go out every 20km.
This is the error recorded by the ecu.

1 Fault Found:
17965 - Charge Pressure Control: Positive Deviation
P1557 - 35-10 - - - Intermittent

What does this fault mean, is it over boost, under boost or what.
Fault only ocurs when towing and only after long uphill's in 4th, Problem cannot be replicated without the caravan in tow.
I tested the n75 and vnt with vag and all seemed fine, is it posible that the vnt can get sticky only when the turbo is very hot after serious uphill towwing.(long full boost run)?
Since the problem improved after I swopped the n75 and blocked the egr vac line, could the egr still be leaking at high engine temps.?
 
Last edited:

TonyJetta

Top Post Dawg
Joined
Sep 15, 2005
Location
Tucson, Az
TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
How much weight are you towing?

Just another thought to consider...
Since this seems to happen at the exremes of power, It sounds like you are working the little motor too much, full power up hill at sustained max boost, and may just need to back off the throttle a little.

Tony
 

Curious Chris

Top Post Dawg
Joined
Jun 11, 2001
Location
Pineview GA
TDI
Jetta Wagon 2003 RIP Rockford IL
Put in a boost gage and drop into 3rd gear on the steep hills.

IMHO if you are towing you also need an EGT gauge as you are pushing maximum fuel and boost on a hill pulling a trailer.
 

dr.diesle

Veteran Member
Joined
Mar 5, 2008
Location
Calgary
TDI
92 golf tdi/01 golf tdi /02 golf tdi/04 jetta wagon tdi/vanagon westy tdi
TDIFanatic1.9 said:
Most of us can't afford 2 cars or a dedacated towing vehicle so the jetta will have to do for the od time's I get a break and go on leave. Most tows are not that far. The TDI engine produces enough torque to be a great towing engine with very good fuel returns
I understand ,Idont have a big truck the point is your car is not designed to pull a trailer the engine has the torque but the tranny cant handle it, have you ever put a new maf on your car?
 

DPM

Top Post Dawg
Joined
Mar 16, 2001
Location
Newtownards, N. Ireland
TDI
2019 Rav4 AWD Hybrid, Citroen C4 BlueHDI
Whaddya mean "your car is not designed to pull a trailer"? That'll be why the manufacturer offers towing brackets that attach to pre-designed, certified mounting points then...
 

dr.diesle

Veteran Member
Joined
Mar 5, 2008
Location
Calgary
TDI
92 golf tdi/01 golf tdi /02 golf tdi/04 jetta wagon tdi/vanagon westy tdi
go ahead and tow I didnt say you couldnt you obviously dont repair vws the trannys can barely handle tourque people like you keep me in buisness rebuilding there trannys so go and tow a house or a cart full of blown up trannys I'd rather use a jap tranny if I had a choice:)
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
Does it only go into limp mode when you have it floored?

Under those conditiions my jetta would not limp at 90% throttle but it would at 100% throttle.

On my Jetta it is not due to poor turbo response, the turbo would be at minimum demand.

So you might be able to get through your holiday with less limp modes.

DanG
 

dr.diesle

Veteran Member
Joined
Mar 5, 2008
Location
Calgary
TDI
92 golf tdi/01 golf tdi /02 golf tdi/04 jetta wagon tdi/vanagon westy tdi
buy a new turbo flush intake then post back or keep wasting time
 
Joined
Mar 9, 2008
Location
South Africa
TDI
VW Jetta TDI 2002
Towing a heavy trailer since day one in 2002. No issues with tranny. 250 000km.

BUT

Went into limp mode a week ago. Incidentally a week after TB replacement. Was a bit of a mess and embarassment going over a mountain pass at 10kph. Towed longer distance than usual and worked the engine harder as trying to keep on time for appointments. Anyway, did the checks, replaced diesel filter and so and so on. Discovered a blown off vacuum tube. Replaced, turbo returned for 30seconds, lost it again. Gave up.

Question: why did vacuum tube blow off???? Doesn't make sense?

Next morning... everything fine (engine cold)?

Replaced vacuum tubes (used thinner inner diameter, all available), discovered one stuck between block and metal tube. probably happened during TB replacement. Theorised that tube became hot and collapsed - was in frayed condition.
 

TDIFanatic1.9

Veteran Member
Joined
Jan 9, 2007
Location
South Africa
TDI
1.9 Jetta TDI
I wish my limp mode flt was as easy to solve as to replace a pinched vac hose. I replaced all the vac hoses on my car just in case but it still went limp. I then swapped the n75 and egr valve's and the car def performed beter (only went limp once), so I suspect a flty (lazy) n75 valve. Have not yet phoned the stealers for a price but I can expect some silly figure as nothing in South Africa is cheap anymore.
 

TDIFanatic1.9

Veteran Member
Joined
Jan 9, 2007
Location
South Africa
TDI
1.9 Jetta TDI
Unfortunataly we'll have to wait a year for the answer as I will be towing the same road again in march 2009. I did however tow the caravan again after the coastal trip but it was only for 200km and a flat road. The trafic was hectic as it was the easter weekend and it forced me to drive prety fast using full throttle alot in 4th and 5th, no limp mode yet. The car also feels a bit more powerfull with the new parts.
I replaced all vac hoses and the n75
 
Top