I reduced and smoothed the WGDC initial and max in all TP positions between 2000-->3200 rpm, and it's worked! :luxhello:

The shudder is reduced to a much less noticeable level and it's a lot easier to drive around town, particularly the shift 1-->2nd gear which was pretty savage before.

Still got some knock issues 0.7-->1.3 2000-3000 rpm but pulled the timing in this region a little (0.35), haven't had chance revisit the car yet to see, but are they worthy of investigation or acceptable in this in this range can you advise?

General driving: https://drive.google.com/open?id=0By...V9RZ1RVX1ZZUUk

without seeing the map I can only really say speak to your mapper for advice on your specific map. If you go too low on the timing then things will get just as bad as too much timing - it may be a better option to bring a little more fuel into the mix (reduce the target AFR a little) or reduce the AVCS target rather than drop a load of timing.

Bludgood, if you don't mind me asking, are you a pro mapper? If so what are you called or company.
Or are you just an individual mapper that's keen on mapping?

I certainly hadn't considered the AVCS aspect and it has been changed in this region of the map, I'll investigate reducing it.

Again thanks for the help!

reopening this shudder discussion... I decided to have a play with boost tuning, and took the car back to stock and started ramping up and playing with the boost and WGDC.

I've been experimenting with low rpm WGDC targets to find the capability of the turbo, mostly in 4th gear, but with some 5th and 6th gears parts pulls also. Anecdotally I've seen that in the low RPM region say 2000-3000 rpm, if the WGDC is set really high and so maxes out (@90%) before dropping down when the boost overshoots target, the shudder occurs at the point it stops dropping, and the WGDC oscillates. It seem considerably more oscillation than when say the WDGC was much lower to start with then dropped down (say from 15%).

In either case the boost doesn't appear or feel to be building any quicker, this is a stock rom with tweeks only to boost and WGDC at this point.

Admittedly I need to carry out some proper back to back logging on this, but initial thoughts anyone, could maxing the WGDC cause the solenoid and/or waste gate to flap when shutting?


https://cimg7.ibsrv.net/gimg/www.sco...0a2082f49f.jpg

"Beware the shudder man, when the boost is fat."


:D

Nice, I remember that ad, very Tim Burton esq!

Quick update though. Totally stock map with cranked up WGDC as below. Shudder/judder :lol: occurs at the same RPM, I struggled to capture any data that shows anything, even with several runs this evening, but did manage to capture the sound of it from inside the car - it sounds and feels like touching the rumble strips (but it's not!), but certainly it sounds a lot more metallic on the recording:

normal play speed @ just before 2 seconds in
https://drive.google.com/open?id=0By...GVyVmtwRFdPS0U

50% slowed down @ ~4 seconds in
https://drive.google.com/open?id=0By...HdQQTVZOXU3aUU


slowed down a lot more on the incident timeframe, it sounds like a metal door opening and fluttering/chattering open & closed.
https://drive.google.com/open?id=0By...m05SGo4Y0FJTHc

(*ignore the 90% in the first 2000 rpm box!)

https://cimg7.ibsrv.net/gimg/www.sco...a641764589.jpg

Update on this shudder issue. I've just fitted an SWRD (Pierburg) 3 port solenoid, and whilst it's nowhere near full dialed in yet, initial results are it's fixed this shuddering issue, and I'm running higher boost than before to! :luxhello:

happy days, was it a stock solenoid before that or a MAC type 3port I can't see it in any of the older posts?

Previously it was the stock solenoid.