why my idle changed after power mods? - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• why my idle changed after power mods? by carrizog60 on 25 Dec, 2006 14:13
• hello
  i have my gtd with some power mods as upping the fuel(no visible smoke on charge and light smoke without turbo)waste-gate closed(1.5bar at max rpm), only 1 silencer on exhaust, lda and boost pin mods.
  
  i feel happy with the power i have gained as the engine fells more powerful on the entire range and mostly on high rpm(past 3000).
  
  the only problem is that now it makes more noise on idle and the engine shakes too much and that is even with more rpm than normal(now is at 1000rpm,on stock form was at 900 and it didn't vibrate as much...)
  
  how can i fix the idle problem?or is it one downside for upping the fuel?
  
  
  thank you
• #1 by SMOKEYDUB on 25 Dec, 2006 14:38
• thats not normal. fuel leaks maybe?
• #2 by carrizog60 on 25 Dec, 2006 14:48
• i dont think so as the pump as no visible fuel stains or else and all the hoses were replaced and injectors cleaned on a specialist in pump rebuilds.
  in idle now the engine makes more of that hammering noise and shakes too much,causing vibration that before didnt existed...
  on 0º temperatures it starts at first but keeps missing and makes some smoke...
  when it starts to warm the smoke disappear and it wont miss anymore...
  
  besides that i am happy with the rest...no smoke and enough power..
• #3 by jtanguay on 25 Dec, 2006 16:13
• my pump did that too, after adjusting idle from the pump.  i adjusted the idle up to around 1100-1200rpm and its working fine now... high idle though
• #4 by RabbitJockey on 25 Dec, 2006 19:03
• this explains alot, i thought it was my motor mounts haha, i just did a higher idle as well, i think a lift pump might be able to get rid of this, but i highly doubt it
• #5 by jtanguay on 25 Dec, 2006 20:03
• with the mods that were done (and the special pump installed) my car was idling really rough... seemed like it wanted to die coming from a stop.  put idle back up and all is well.  very hard to stall it now.. plus way more power
• #6 by carrizog60 on 26 Dec, 2006 03:27
• well i didnt want to up more the idle.. even at 1000rpm it looks way high.
  everybody keeps telling me that... :oops:
  what about the more noise it makes?happened to you too?
  besides that its ok, just going to install a external oil cooler(i still have the oem oil/water crap)
• #7 by eci on 27 Dec, 2006 12:41
• the rough idle is caused by late pump timing.
  when you adjust the fuel screw it extends the injection but it still begins at the same time.
  you have to advance the pump timing so that the bigger amount of fuel has time to combust.
• #8 by flash319 on 27 Dec, 2006 15:47
• What eci said.  When you adjust the max fuel screw you are adding more fuel in all throttle positions but the timing advance is controlled by engine speed not metered fuel.  
  I guess you could try adjusting your mechanical advance (cold start lever) so that it is advanced a bit at idle and see if that fixes your idle.
• #9 by Benjamin on 27 Dec, 2006 15:51
• i know overfeuled injectors at full thottle can be a problem,
  but i wonder this little bit is good to make it idle more rough.
  
  Greetz, Benjamin
• #10 by jtanguay on 27 Dec, 2006 20:49
• my timing is at around 1.06mm checked my andy2.
  
  i might have to use the idle stop screw to adjust my idle rather than the service idle screw.  i've had other vehicles where i've increased the fueling with the fuel screw, and adjusted the idle with the service idler, and have had issues with the car stalling and having no balls down low...  very weird.
  
  i dont mind the high idle at the moment because it helps warm the old beast up a bit, and cold starts are pretty decent (although one morning it was a bit rough... possibly due to a bad battery... 600CCA is definitely not cool!!!)
• #11 by carrizog60 on 28 Dec, 2006 03:36
• so, push the cold start lever a bit and use the residual fuel to low the rpm right?
  i will check that afternoon.
  my pump was timed and injectors cleaned but they coul have it timed to stock timing...
• #12 by flash319 on 28 Dec, 2006 07:44
• The cold start lever advances the timing up to 2.5degrees depending how far you pull it.  You can try this and see if it is your problem.  If it does fix it then I would advance your pump timing a bit.  Once your RPM gets above a certain point the hydraulic advance takes over so the lever only has effect at idle and just above.  If you like how it runs above idle you may not want to adjust the pump timing and just use your cold start lever to correct your idle problem.  If that is your problem.
• #13 by carrizog60 on 29 Dec, 2006 08:32
• havent got the chance to try it but i also feel that below turbo spooling zone,even with incresed fuel, the engine is a bit slow to rev up...
  is this also a retarded timing issue?
  
  today made a 0-100km/h(0-60mph) and even with clucth slipping on 1st and 2nd gear i made 8seconds.
• #14 by flash319 on 29 Dec, 2006 11:25
• Well it is a diesel remember.  The explosion is not like gas.  Also without the boost diesels are not very good at pulling enough air in on there own.  You need less fuel when no boost is present but when you adjust the Max fuel screw you add more fuel across the rpm range.  YOu will have to have a trade off at some point.  Or compound turbo setup.