1.9tdi ALH limp mode and low mpg Q's

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by barkl0r, Apr 9, 2012.

  1. barkl0r

    barkl0r New Member

    Joined:
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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    Hi all,

    I drive an Octavia - it shares the 1.9tdi ALH engine from the Passat, Golf etc...

    This is a new car to me, it has 154k on and is having a new gearbox replaced (damaged syncro, stiff diff, knocking sounds), new clutch (nominal thickness and glazing), water pump & timing belt (peace of mind) and general servicing.

    The main issues I have: car going into limp mode, which, through reading is either MAF or fuel related. I have a new MAF to install when it returns from the mech, and I will replace the filter.

    The symptoms:

    Usually when I go past a certain speed or overtake on the motorway there is a very definite step down in power, the engine doesn't go above 3k and won't accelerate past a certain speed in 3rd or 4th. Feels like the turbo has been removed from the equation. When you try to accelerate from 0 in this limp mode it feels like you are dragging a 1tonne trailer behind you! Off and on again resets this mode, and for most driving this doesn't appear.

    I'm also getting lower mpg than expected: in the 40s despite going easy. My thoughts: terrible wheel alignment, stiff diff (part of the gearbox issue), dodge MAF. This current tank is looking like it may get between 45 and 50mpg; one day - 60 miles of motorway driving at 70 ish, then gentle driving for the remainder. In my old 1.8tddi focus this driving style would average 50-55mpg.

    Thanks for reading!
    Mike
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  2. barkl0r

    barkl0r New Member

    Joined:
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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    Just to clarify; I am speaking in terms of a British gallon: 4.54L, not a US gallon: 3.7L.

    This would adjust my figures:

    45-50mpg; approx 36-41mpg

    40mpg; approx 32mpg

    50-55mpg; approx 41-45mpg.

    The adjustment is approx x.81 to convert British to US. Unless I am way wrong!!

    The weather isn't all that warm here at the mo, it was between 3*c (37F) to 9*c (48F). Is this cold enough to affect the MPG much?
  3. chittychittybangbang

    chittychittybangbang Administrator

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    Car:
    2006 Jetta TDI
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    CT
    you're getting winterized fuel probably...thanks for reminding us about the us-british diff in gallons so yes that is still a little low!

    Yes, check out limp mode article, most of the common causes are in there and it's impossible to even guess without more clues!
  4. barkl0r

    barkl0r New Member

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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    You are right. No sense guessing.

    There was an air bubble in the clear fuel line. I will replace the filter, and see if that improves the initial cranking time of the car. After that I suspect the lift pump/in tank doosie?

    Mike
  5. Seatman

    Seatman Active Member

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    Car:
    2000 Mk4 Golf Estate 1.9tdi 174 bhp
    Location:
    Scotland
    Mods:
    PP764's, turbo and mapping
    Well first you'll need to get this limp mode figured out then look at the mpg, maybe tweak the timing and the IQ settings, that should help. I suspect part of it is probably due to the current limp mode and low power problem.
    The car uses the turbo to increase the compression in order to burn the fuel better there by giving you more bang for your buck so you need less foot pressure to have decent power for cruising etc.
    Also you don't have a lift pump in the tank, that's the PD's and newer ones, you like me just have a sender unit.

    Anyway welcometomyturbodies
  6. barkl0r

    barkl0r New Member

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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    Thank you for the clarification Re: lift pump/sender unit. The sender can become blocked too, correct?

    My mechanic is replacing the timing belt etc... This should correctly set the timing, if done correctly, or is there any ECU related timing?

    Out of interest, are there many people boosting these engines? From what I read it can take 18psi. I have gotten used to the snappy-ness of my chipped focus... I certainly wouldn't mind if this had a little more shove/go about her.. And just keep the angle between the right foot and the floor disiplined to help mpg ;)
  7. cnieto2

    cnieto2 Member

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    Car:
    2003 Jetta TDI ALH 5 Speed, 2006 Jetta TDI BRM DSG, 2001 New Beetle 1.8 T Auto
    Location:
    Austin, TX. 78760
    "Usually when I go past a certain speed or overtake on the motorway there is a very definite step down in power, the engine doesn't go above 3k and won't accelerate past a certain speed in 3rd or 4th. Feels like the turbo has been removed from the equation."
    Those are the exact symptoms my 2003 Jetta was showing just about a month after I bought it brand new.
    It would have great acceleration until certain point, then just disconnect, and be unable to either accelerate fast or pass the 65 mph mark. It was very frustrating, especially on a brand new expensive Jetta.
    "It's man made, can not be perfect", the service department manager said. But inmediatly accused me of some how modifying the pressure to the turbocharger manually; something I could not even dream of doing back then, I was just so happy with my car.
    They found it was a lock washer or nut on the turbocharger that had been lost (fallen).
    In the process, the guy also modified the computer settings, he told me, and the result is that ever since then the car was not fun anymore. Good car, good fuel economy, etc, but mediocre performance.

    I hope this helps. Someone with more knowledge will expand on items like N75 solenoid valve, waste-gate actuator, etc.
  8. rosscer

    rosscer New Member

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    CCM from mkiv Golf, G60 Flywheel
    Your symptoms are identical to mine on an 01' Octavia tdi with 130k miles. In 3rd/4th reving to speed up or overtake, then...nothing. Car just turned to a lump. The limp mode resets when the ignition is turned off and the car restarted (at the lights usually).

    It turned out to be the well documented stuck turbo vanes. I did check all the other stuff 1st though, vac lines, N75, intake hoses, etc, but to no avail, I had to get my hands dirty and I did the turbo removal and clean myself. It took a day and a few new gaskets.

    Edit: If you need more power from your car, and the turbo might be borked and in need of removal, now might be a good time for an upgrade to a slightly bigger one?

    I was getting fairly good mpg from the car for the few months it was stuck. Mine may have been jammed in a middle position, while yours may be stuck either fully open or fully closed?? Could this be a factor in your MPG issue?

    Ross
    Last edited by a moderator: Apr 10, 2012
  9. barkl0r

    barkl0r New Member

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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    Just to check back into the thread.

    Thanks for the advice and thoughts guys. The car was in the garage getting a new gearbox and clutch fitted. Put a second hand gti golf box in. Clutch kit is a bit pricey alright, but hey, it is nice to be able to use my gears again! Previous owner must have really crunched the syncros.

    I have yet to have the wheels aligned and the turbo checked. I have a set of 17" A4 alloys and some 215 45 17 Matador MP46 tyres set to go on after I tidy the wheels up, set of wheel nuts to accomodate the depth of the alloy too.

    This tank looks like 50mpg is on the cards (british gallon). Not amazing considering I'm driving real easy.

    The good news - the mechanic says the car has been really well maintained and serviced despite the gearbox being busted.

    New parts:

    Clutch, shocks allround, pads and discs, vacuum reservoir, vacuum hoses, vacuum distributor/regulator things, EGR actuator, timing belt, water pump, aux belt, OSF hub, bottom ball joints, tie rod ends, gear lever cabling.

    Basically the only thing not changed looks like the engine... I'm hoping she will serve me a decent time... And I'm a little sad to now be selling my Focus which is a real gem.

    Anyway - I'm painting and tidying alloys this week, ill do an oil flush and change the filter and oil in a week, fuel filter too. All fun!

    cheers all!

    Mike
  10. barkl0r

    barkl0r New Member

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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    UPDATE:

    I have replaced the fuel filter and MAF sensor. Same problem with the idle mode.

    I hooked up the VAG SCANNER to the car, and got the 17965 error code - charge pressure control; positive deviation. Overboost?

    I think the variable vanes on the VNT turbo are sticking open like one poster here suggested. This would defo explain the MPG and limp mode. My last tank I was driving fairly/very carefully and got almost exactly 50mpg; 219 miles in 20 litres.

    I have seen this: http://www.audi-sport.net/vb/a4-s4-forum-b5-chassis/107121-un-sticking-your-tdi-vnt-turbo-vanes.html

    And I am going to try it tomorrow/weekend. See if I can't get those vanes unstuck!!

    The car has a new N75 valve in it - it would seem, so perhaps the previous owner tried that solution.

    Anyway - I will keep you updated. It is certainly running better with the new filter and MAF sensor. Both made a difference independently which was nice.

    Kindly,
    Mike
  11. barkl0r

    barkl0r New Member

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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    UPDATE:

    Did the Mr Muscle clean on the turbo - certainly the turbo sounds much quieter, but the over boost error still exists.

    One thing I notice is that on the vacuum pump the vac hose connector mathingy is very loose... it appears broken to me - and repaired with tape. Not sure if this could cause an overboost error, but I will replace this and report back.

    I am also having a long crank time (imo) - fuel filter did nothing to fix this - I am going to inspect and or clean the tank sender unit. I can't find these easily available for purchase.

    I'll maybe invest in some Redline transmission fluid too as 5th is a bit finicky as can 1st.

    Kindly,
    Mike
  12. barkl0r

    barkl0r New Member

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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    UPDATE:

    I replaced the vacuum pump - the ABS problems I was having have gone, but the overboost error 17965 charge pressure positive deviation, still exists. Time to check the hoses, solenoid, actuator and then bite the bullet and take the turbo off and rebuild it as I reckon it is sticky vanes. As an indicator the EGR valve was very coked up so I wouldnt be surprised the same of the turbo.

    The last mpgs: 45 & 47.5mpg (british gal.) which was driving with no consideration to MPG. The second higher MPG the car was driven harder, but I had a new set of Matador MP46 Hectorra 2 tyres fitted and they seem to roll incredibly well, as well as being incredibly grippy in the wet and dry. I bought them after reading reviews, and they really perform so well!

    Anyway - I'll check back in, in the off-chance someone finds this useful.

    Kindly,
    Mike
  13. Hoff6282

    Hoff6282 Member

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    Car:
    2000 Volkswagen Golf TDI ALH
    Location:
    Brighton, MI
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    Egr delete, lift kit, skid plate, pp520 nozzles
    Very interesting thread, I'm having similar symptoms with my 2000 Golf. Thanks for keeping us all updated, and I'm looking forward to hearing how it all goes for you.

    Goodluck!
  14. barkl0r

    barkl0r New Member

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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    Just checking back in.

    I've had a busy month, so I really only got a quick look at the turbo. Today I will try vac testing the actuator.

    Revving the car to 4k and observing the actuator - nothing moves. Moving the actuator by hand seems smooth and feels like 5-6mm movement. Makes me think the vanes aren't sticky but the actuator, N75 or lines are shot. Will report back!

    Mpgs in and around 47 (british gallon) with the current tank just past the 50 mark with a lot of babying. Not all that impressed with these figs, but if the turbo isn't running as it should I'll not be too hasty in cursing it.

    I am going to check the snow screen in case it happens to be blocked and starving the engine of air. Probably not the case, but worth a look!

    Cheers,
    Mike
  15. barkl0r

    barkl0r New Member

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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    UPDATE:

    Vac lines checked - all fine.

    Actuator checked - hosed! It wouldn't hold any vacuum or positive pressure (I checked both). It seems to have 5-8mm movement by hand and ZIP under vacuum. The vane arm/lever seems to move easily, so hopefully this isn't going to be an issue!

    In my car it looks like the previous mechanics/owners were trying to find this issue, as all vac lines, solenoids etc look new. This is maybe worth checking in your own vehicles if you are experiencing similar things.

    I am going to order and replace the actuator - I will report back with my findings.

    Starting to look like I might have a functioning VNT turbo soon!

    Mike
  16. barkl0r

    barkl0r New Member

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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    UPDATE:

    New actuator fitted. Didn't move. Check valve on the vac line busted. Part number: 046 905 291A - its like hens f***ing teeth this part - or insanely expensive for a valve. I'm going to try and clean this. Failing that I will probably machine one. I refuse to pay $69 for a 2 cent piece of plastic FFS!!

    Hopefully an end to this will appear.

    Mike
  17. barkl0r

    barkl0r New Member

    Joined:
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    Car:
    Octavia 2004 mk1 ~ 1.9tdi ALH
    Mods:
    AHF injectors, re-map, PD150 intake & ASV
    UPDATE:

    Replaced the check valve - the original part was hard to find and over-priced, so I fitted a check valve from a SAAB:

    http://www.ebay.com/itm/320915544229

    The connectors were slightly larger than the original one, however the 3mm silicone hose stretched over it with some persuasion.

    Replaced all vac lines with silicone.

    Drilled out the check valve on my tank sender unit on the send line - left the one on the return - it was dirty/part clogged, so here's hoping for shorter crank times on cold mornings; power is much better above 3k RPM. More info here:

    http://forums.tdiclub.com/showthread.php?t=68872

    I am going to install and run the VCDS software to enable the cruise control I am fitting, and to log the duty cycle of the N18, N75, anti-shudder valve, turbo; I am going to have to re-adjust the VNT lever no doubt!

    Mike

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