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stevie 77 930 stevie 77 930 is offline
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Join Date: Jan 2008
Location: Chatsworth, CA
Posts: 599
Finally set my AFR's w/ BL WUR

Inspired by the "the slilent killer of 930 power and fuel economy" thread

Well after several weekends and some bad rainy weather here in LA, I finally had a chance to dial in my Leask WUR on my 77 930 this weekend. I was able to borrow a LM1 and CIS pressure guage from my local BMW shop owner. My tuning conditions were less than perfect, IE i used a c-clap to hold in the O2 senser in the tail pipe and I had to hold the LM 1 unit in my hand while driving. I did have a deserted street in a business park that was 1/2 mile long...not perfect but I think I got it pretty good.

Here are some of my pre-adjusted #s on a car that ran pretty well before I made any adjustments:

warm idle AFR 13.10
crusing AFR 13-13.6
WOT AFR 9.8- 10.2

I am running total stock internals and stock 3LDZ. I do have have later style exhaust with J pipe, a garrettson intercooler with 965 BOV and I am running .90 boost with 29 degrees of total advance. I am also running a 84 carrera 915 gearbox with LSD. Calif car so I am running a smog pump too.

I first set my idle AFR's to 14.50 in the garage. I then headed out to set crusiung AFR's armed with a few wrenches, allens, and a pressure gauge. Using Brian's WUR make these adjustment pretty staight forward. I increased my warm pressures to 3.85 bar and i saw my cruising AF'R's get to 14.5 so i was pretty happy with that. Next was WOT adjustments. While making runs, I notice the AFS drop quickly at around 3000 rpm, by the time I got to 5000 rpm I was making full boost and saw AFR in the low 10's or even 9.9. I first increased the threashold at with pressure would drop. Slight adjustments to 3 screws at the bottom of WUR, and I managed to delay the rich condition until 3500 rpms. Next, I needed to increase WOT presures. Again, the adjustable WUR made the relatively easy. A good wack to the bottom diaphram , I saw WOT AFRs' increase to 11. One more time and I got the AFRs to 11.60-11.80 on WOT.

Gone is the eyewatering exhaust on idle and I am hoping to get rid of the black exhaust residue on my bumper and more importanly, get my gas milage to something more than 11-12 MPG's on the fwy. To soon to tell, but the car is running absolutely prefect. So here are my #'s....
14.50 idle
14.40-14.50 cruising
11.60-11.80 at WOT at full boost.

This morning I had a tough time starting, so I check my cold pressures and they were to high @ 2.75bar. One more time with the pressure gauge and lowered the pressure to 1.90bar. I think I finnaly got it.....

I look forward to your comments. Thanks to all on this board who provide such great information.
1974 914
2018 GTS
2017 BMW 340I M Sport Package
1977 930 (recently sold)
1976 911S , 1973 1/2 911T, 1972 911E (long gone)

Last edited by stevie 77 930; 01-24-2010 at 10:40 PM..
Old 01-24-2010, 10:36 PM
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