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    Thread: 1.6 IDI Timing advance Mod....

    1. 04-18-2007 07:51 PM #1
      Quicker acceleration and better mileage... Change the injection timing advance curve...
      This CAN be done on the car without removing the injection pump. On the side of the pump facing the front of the car, there's a round plate with two screws. This is where the advance mechanism lives. Before you begin, go to the dealer and get the seal kit for the advance piston housing. It'll consist of two large green o-rings, several smaller ones and an e-clip. Cost is about $5.
      Loosen the cover, using a T30 Torx bit. Now you are going to remove the screws and cover. Be careful as there is a rather large spring behind the cover, as well as some spacer shims. Once the cover is off, you should find two shims between the spring and cover, and if you remove the spring, there will be one more shim. Take all of them out and look at them. Take the thickest one and set it aside... you won't be needing it. Now, smear some vaseline on both ends of the spring and stick a thin shim to each end. Insert the spring back in and put the cover back on, using a new o-ring. You must have a shim on each side of the spring, otherwise the spring will "machine" the aluminum cover and advance piston, filling your pump with fine metal filings... thus destroying the pump and injectors. Take a ride and feel the throttle response!
      For those of you that have access to parts for these pumps (new or used), you can get even better throttle response and power by changing the advance spring too... Just replace the spring currently in your pump with a "lime green" colored spring. This spring has the softest spring rate and allows the pump to advance the timing MUCH sooner, with more overall advance. These springs are commonly found in early rabbits (pre 80) and Vanagon diesel pumps. Color codes from softest spring rate to hardest is as follows... Green, Gold, Red, yellow, silver, and blue. The hardest spring rates will give the LEAST timing advance.


      Modified by TurboDieselTech at 6:29 PM 4-19-2007

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    3. Member
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      04-18-2007 09:41 PM #2
      Interesting tip and it sounds easy to do, thank you for your post.
      Possibly this was the difference between my 1986 Golf and my wife's long gone 89 1.6 Jetta which was had noticibly stronger acceleration and was about 9 mph faster, 99 mph vs 90 for my Golf.
      What is the downside to this modification; why didn't the factory do it for later IDI diesels?

    4. 04-18-2007 09:48 PM #3
      Quote, originally posted by Tinker Toy »
      What is the downside to this modification; why didn't the factory do it for later IDI diesels?

      No downside... I've done it to every 1.6 I've owned. Not one problem.
      The ONLY reason the factory didn't do this, is emissions. The car would have never passed the NOx emissions test to get in the country. Advancing the timing drives the NOx emissions through the roof.

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      04-19-2007 10:49 AM #4
      Very informative post, thank you!

    6. Member V-TEC this!!!'s Avatar
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      04-20-2007 09:02 AM #5
      I love the IDI diesel!!! almsot every modification is free!!! plus you get the added bonus of better gas mileage!!!! Will definatly be trying this!!!!
      Do you have some pics of this maybe???? Im a very visual person!!!

    7. 04-20-2007 07:34 PM #6
      Hmmm... no pics, but I'll definitely take some the next time I do a pump.

    8. 05-04-2007 03:51 AM #7
      quick question, can the same result like removing a shim be achieved by just turning pump towards engine advancing it that way?whats the difference.? did the mod tonight, already had green spring in it, now idling smoother and faster, will take for spin in am. what if i grind down the spring by another mm or so? will that be even better? will turn up fuel next and add intercooler to my now td 84 jetta-85 td 1.6 l motor- svo hydrogen boosted fn tranny ride.how can i get turbo started to kick in sooner?maybe get 15 psi? only have metal lines to turbo, ordered egt gauge before turning up fuel. read forums not very informational on my garret t3 setup.

    9. 05-04-2007 07:38 AM #8
      Turning the pump gives you more static advance. The advance still increases at the same rate in relation to engine speed... aka dynamic advance. Changing the spring and removing a shim gives a quicker dynamic advance... meaning the advance curve is changed so the advance comes "quicker" as the engine increases rpms. Grinding the spring will destroy the spring's temper. Also, advancing beyond what the light green or "lime" spring will give you can cause problems. Over advance will cause the combustion temps to soar, overheating the pistons and the head. The rings also get very hot making them prone to cracking.

      Turning up the fuel will give a little quicker turbo response if you advance the static timing as well. Setting the static at 1.05mm is a good start and will keep the EGT down a little. I've run mine at 1.10mm with no apparent problems, other than never having to use the cold start advance These engines are pretty well known for turbo lag, so don't expect miracles.

    10. 05-04-2007 10:59 AM #9
      A Garrett T3 with stock exhaust will not develop much boost before 3000 RPM even if you crank up the fuel so much you can't see the guy behind you... it has reasonably large impellers and just takes some time to get going.
      If you want 15 psi you'll need to disable the BOV and block off the wastegate... the turbo will then be open-loop so you'll be moderating boost with your left foot while watching the EGT, boost, and oil temp gauges. You still won't start to really spool until 3000 rpm though.
      Vince Waldon
      Edmonton Alberta Canada
      2001 silver TDI Jetta, .205s and Malone Stage 1.5
      2001 blue TDI Jetta, .216s, SB III, and Malone Stage 3. grrrr baby...very grrrrrrr ;-)

    11. 05-04-2007 09:28 PM #10
      does the shim mod increase static advance as well, is that why it is idling faster now? Took it out for a spin, noticeably better response, no smoke , which is good.I don't have to worry about over advancing till it gets black smoke, correct? Static timing was at 1.o, is it still at 1.0 since mod, did not move pump? My vw mechanic says 1.25 static advance is ok, have my doubts.How about drilling out a 1-2 mm hole in advance mechanism cover. have you tried this?

    12. 11-14-2007 08:29 PM #11
      Would it be possible for you to post the part number for the Lime Green spring? I talked to a friend at the local injection pump shop today and he said they need either a part number for the spring or a pump number it would be in. Thanks.
      Jim

    13. 11-14-2007 09:49 PM #12
      So Im really not sure why, but in all my diesel travels, I havent heard of the 1.6 IDI TD. Just wondering what IDI is or what does it stand for? I have had mostly 1.6 TD's so im not really sure what the difference is.... if there is one.
      Kind of strange... I can tear a 1.6 TD apart and put it back together blindfolded but Im finding some terminology that leaves me scrating my head from time to time. thanks.

    14. 11-14-2007 10:05 PM #13
      It's actually just semantics...
      IDI stands for "Indirect Diesel Injection"... meaning the injector sends fuel indirectly into the combustion chamber via a precombustion chamber.
      TD stands for "Turbo Diesel"... meaning a diesel with a turbo charger
      TDI stands for "Turbo Direct Injection"... meaning a diesel with a turbo that also directly injects the fuel into the combustion chamber.
      VW made IDIs in two flavours, normally-asperated "NA" and turboed "TD". All of the DI engines they make are TDIs.
      Clear as mud ??!!!
      Vince
      Vince Waldon
      Edmonton Alberta Canada
      2001 silver TDI Jetta, .205s and Malone Stage 1.5
      2001 blue TDI Jetta, .216s, SB III, and Malone Stage 3. grrrr baby...very grrrrrrr ;-)

    15. 11-14-2007 10:13 PM #14
      ah haaa! Thank you very much for taking the time to spell it out for me. I had always just called the pre-TDI's TD's and never heard them referred to as IDI's, and was told that TDI's stood for Turbo Diesel Induction which didnt make sense in itsself let alone that all engines have some form of induction whether forced or not. sweet!
      Youre the man vince

    16. 11-21-2007 08:51 AM #15
      doyou know if these green springs you speek of are still avaiible or where i can get one i have a red in mine

    17. 11-21-2007 10:53 AM #16
      anydub,
      What vehicle do you have? A red spring would seem to be better than the silver one I have. Could you post the pump number of your pump. If I can't find a green one I would settle for a red one.
      Jim

    18. 11-21-2007 11:11 AM #17
      Quote, originally posted by anydub »
      doyou know if these green springs you speek of are still avaiible or where i can get one i have a red in mine

      Unfortunately, the springs are no longer available new. You'll have to scavenge one from an early Rabbit diesel or Vanagon diesel. Make sure you get a lime green spring. I've seen some dark green springs from time to time with a higher spring rate in rebuilt pumps. You might be able to find one with the part numbers, but it's doubtful. Try these:
      VW#..................................Bosch
      068-130-677-F....................1 464 619 322
      068-130-677-G....................1 464 619 323
      These numbers are for the ones found in Vanagons. You'll know by the color of the spring as to which one is correct. I believe the first one is the correct one.
      Reading back, I saw a post here about trying to increase boost to 15 PSI. A mechanical boost controller installed inline with the wastegate will allow 15 psi... or cut the hose going to the wastegate and install a short piece of plastic pipe. Take a hot needle and poke a few small holes in the plastic pipe to bleed off a little boost pressure. keep poking holes until you get 15 psi of boost. It fools the wastegate into sensing less boost. Next you can disassemble the blow off valve (BOV) and adjust the blow off pressure. There's a thread on this site with instructions, but you'll have to search for it.


      Modified by TurboDieselTech at 8:15 AM 11-21-2007

    19. 11-21-2007 11:30 AM #18
      Thanks TDT!
      Jim

    20. 11-21-2007 06:29 PM #19
      i have a 83 rabbit and the pump vw # is 068 130 109 d bosch # is 927 246 87563. i have 2 of this pump number so i would assume they are the same correct

    21. 11-21-2007 07:38 PM #20
      Thanks dub.
      TDT, would you agree the red spring would be better than my silver one if I can't find a lime green one??
      Jim

    22. 05-30-2008 02:33 PM #21
      Quote, originally posted by TurboDieselTech »
      Quicker acceleration and better mileage... Change the injection timing advance curve...
      This CAN be done on the car without removing the injection pump. On the side of the pump facing the front of the car, there's a round plate with two screws. This is where the advance mechanism lives. Before you begin, go to the dealer and get the seal kit for the advance piston housing. It'll consist of two large green o-rings, several smaller ones and an e-clip. Cost is about $5.
      Loosen the cover, using a T30 Torx bit. Now you are going to remove the screws and cover. Be careful as there is a rather large spring behind the cover, as well as some spacer shims. Once the cover is off, you should find two shims between the spring and cover, and if you remove the spring, there will be one more shim. Take all of them out and look at them. Take the thickest one and set it aside... you won't be needing it. Now, smear some vaseline on both ends of the spring and stick a thin shim to each end. Insert the spring back in and put the cover back on, using a new o-ring. You must have a shim on each side of the spring, otherwise the spring will "machine" the aluminum cover and advance piston, filling your pump with fine metal filings... thus destroying the pump and injectors. Take a ride and feel the throttle response!
      For those of you that have access to parts for these pumps (new or used), you can get even better throttle response and power by changing the advance spring too... Just replace the spring currently in your pump with a "lime green" colored spring. This spring has the softest spring rate and allows the pump to advance the timing MUCH sooner, with more overall advance. These springs are commonly found in early rabbits (pre 80) and Vanagon diesel pumps. Color codes from softest spring rate to hardest is as follows... Green, Gold, Red, yellow, silver, and blue. The hardest spring rates will give the LEAST timing advance.

      Modified by TurboDieselTech at 6:29 PM 4-19-2007

      this modification to the timing advance mechanism sounds too good to be true (quicker acceleration + BETTER mpg).
      want to know how well this mod can help n/a diesel engine under heavy load like going up steep uphill climb?

      Modified by ordonez1970 at 11:51 AM 5-30-2008


      Modified by ordonez1970 at 12:08 PM 5-30-2008
      1992 jetta GLI.
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    23. Member Baron VonZeppelin's Avatar
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      05-30-2008 10:53 PM #22
      Anyone find a place to buy the Lime Spring ?

    24. 06-02-2008 04:09 PM #23
      im pretty sure i found a place but i need to know the measurement of the spring as the listing doesnt give you the colour. they come in 0.2mm increments.

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      06-04-2008 09:20 AM #24
      Quote, originally posted by ordonez1970 »
      this modification to the timing advance mechanism sounds too good to be true (quicker acceleration + BETTER mpg).
      want to know how well this mod can help n/a diesel engine under heavy load like going up steep uphill climb?

      You are right. It is too good to be true. This is kind of a hack job which, when done to a pump with the correct internal pressure, could result in engine damage from too much advance.
      See this link for the correct method of changing internal pump pressure: http://vwdiesel.net/phpBB/viewtopic.php?t=7817
      And here's a few who have done it and could find no measurable gains:
      http://vwdiesel.net/phpBB/viewtopic.php?t=7781


      Modified by Dieselkraftstoff at 8:02 AM 6-4-2008

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