Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Technical BBS > 1- Porsche Technical Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Alan L's Avatar
 
Join Date: Apr 2006
Location: New Zealand
Posts: 3,185
tuning problem

Folks,
I've been struggling with this one for ages (months) in between a million other jobs to get this car back on the road(track).
I am sure it is a leaness problem, but I can' t isolate the cause. It runs rough and intermittently on various cylinders on cold start up. Eventually, if you are lucky, after a short period all 6 will kick in (backfiring too). I managed to get it going well enough to take it for a few squirts on the road a day or so ago. There is hestiation and slight bogging down under throttle before boost comes on. Under boost it seemed to go very well, pulling away in 4th like a rocket up to around 100-120 mph before I backed off on the wet greasy road.
I now have the advantage of an AFR, and the numbers tell me under boost I was running mid 11's - 12. But off the throttle, or low throttle cruise14's +.
It seems by the numbers and feel, the car is running lean at low throttle openings, I keep tuning it richer - and then it is running a bit rich under boost. If I lean the boost end off - it is too lean at idle and low throttle and runs/starts like a pig.
My best guess is an air leak. I have spent hours chasing leaks and replaced most everything that looked like leaking. I am about to start over again - I am still loosing about 20 liters/min leakage at 0.5 bar boost pressure. These leaks I presume are air leaks under vacuum (leaness) and boost leaks under pressure. The ones I know of are at the throttle spindle and air screw. Whether they add up to 20 l/min,I don't know.
I have checked the AAV, and will check again it is still functioning (was broken first time I checked - fixed). I have checked the cold start valve, and will check again (was broken first time I checked - fixed). I have calibrated the injectors (twice and they are within 1-2 %).
I am at the point of having to go over everything I have already been over - often many times, and still not fingering the source of the problem. Have I missed something?
Checked WUR pressure function too.
It does not seem to respond properly to the mixture screw tuning - there is no sweet spot between rich and lean - normally I can tune to the point where either range just becomes eveident and hit a mid spot which gets you very close. There seems to be no steady mid spot - just a point where it is better than either way from there.
Thanks
Alan
Old 05-25-2008, 01:11 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
930gt-40r's Avatar
 
Join Date: Jan 2007
Location: Boca Raton, FL
Posts: 2,063
I know you checked it, but it still is seeming like a bad WUR, I would try swapping it out if you could.
__________________
Kris @ Tech9
86' 930/GT-40R Sold
94' Rustang GT daily (long gone)
2008 C6/Z51 Corvette
Old 05-25-2008, 02:29 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
A fellow Pelacanite
 
NathanUK's Avatar
 
Join Date: Nov 2006
Location: UK
Posts: 2,002
Garage
Why not just get Brian Leask to mod it. You could get the new UTCIS digital WUR instead.
__________________
1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG.
Fitting - New service kit.
Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head.

1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods.
Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit.

http://www.danasoft.com/sig/Iamnotanumber.jpg
Old 05-27-2008, 02:06 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
David's Avatar
 
Join Date: Apr 2002
Location: Houston (Clearlake), TX
Posts: 8,578
Garage
Quote:
Originally Posted by 930gt-40r View Post
I know you checked it, but it still is seeming like a bad WUR, I would try swapping it out if you could.
+1
__________________
2014 Cayman S
2011 Cayenne Turbo
1979 930 (475 rwhp at 0.95 bar)
Old 05-27-2008, 02:57 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 02:58 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.