Author Topic: A4 b5 boost Question  (Read 807 times)

0 Members and 1 Guest are viewing this topic.

1234

  • Guest
A4 b5 boost Question
« on: April 27, 2010, 12:16:25 pm »
Hi every one I've had my a4 1.8tq aeb Going now for about a week with the t3/t4 turbo tial 38mm wastegate . when running boost peaked around 4.5k but yesterday i noticed that when in first gear boost did not kick in until after 5.5k but in second it will come on at 4.5k any idea's on what it could be ? could the wastegate not be opening properly ? or the old internal wastegate flap came unsealed ? ideas would be good I'm still saving to do injector's and fueling upgrades and remap

Offline Filx

  • ##
  • **
  • Posts: 4856
Re: A4 b5 boost Question
« Reply #1 on: April 27, 2010, 02:44:36 pm »
Did you have no boost until 5500rpm in 1st or just not peak boost?

If it's the latter it's possible that the car just doesn't develop enough load to spool up the turbo before ~4500 in 1st gear. The same thing (but worse) happens in my Starlet (1.3 litre with VF22 turbo) - you just get through 1st gear so quickly the turbo never gets a chance to get working (unless you're using the 2step to launch it).
FAIL - First Attempt In Learning

1234

  • Guest
Re: A4 b5 boost Question
« Reply #2 on: April 27, 2010, 03:22:59 pm »
it was boosting in first gear from 4 4.5k peakboost all the way around but now its around 5.5k when i hear the wastegate open then i have to change gear as theres no more rpm left . it might sound weird but it started doing it when i took my 18's off running 225/40/18 and put the standard 195/60/15 on
« Last Edit: April 27, 2010, 03:24:48 pm by 1234 »

Offline Filx

  • ##
  • **
  • Posts: 4856
Re: A4 b5 boost Question
« Reply #3 on: April 27, 2010, 03:30:25 pm »
Yeah that would kind of fit with my theory. The 18s are around 3.5% bigger rolling radius, plus will be heavier = more load on the car in all gears and slower through each gear. That might just be enough difference to get the turbo on boost earlier in the rev range in 1st. Or I could be talking a load of crape  :D

One way to test is bolt the 18s back on I guess.
FAIL - First Attempt In Learning

1234

  • Guest
Re: A4 b5 boost Question
« Reply #4 on: April 27, 2010, 03:34:38 pm »
thats what i was thinking will try that . if not will pull it all apart again  :laugh:

1234

  • Guest
Re: A4 b5 boost Question
« Reply #5 on: April 28, 2010, 11:07:54 am »
found the problem was the old internal wastegate flap as i took it for a drive and there was no boost at all now have to pull the turbo back out and get it fixed up just so happens it started doing it when i put the standard wheels on