calling those with tiis and AFM gauges (Bill, Justin, JimG)

[thehackmechanic]

Bill, Justin, Jim, that's you :^)

As per prior post (http://www.bmw2002faq.com/component/option,com_forum/Itemid,0/page,viewtopic/t,376635/) I've turned the verboten screw a mind-numbing two turns rich and gotten the car to:

--stop backfiring when letting off the throttle

--read more in the center of the AFM gauge in a variety of driving

--read about 14.5 under WOT for a variety of

But on steady throttle or light acceleration, the gauge is still all over the map, swinging from about 12 to about 16.

Jim, you were describing these very sorts of swings before you advanced the throttle body linkage (partially covering the synchronization hole). Did these swings go away once you settled on a setting?

Bill, you said "I stay at 13.2 -14.2 at all times." Does that include getting on and getting off the throttle?

Justin, you described idle around 13, WOT around 13.5, and cruising around 15.5. Does it live within those goalposts or does it swing outside them on partial loads?

Thanks.

--Rob

[BillWilliams]

"At all times" is not a correct statement by me. I should have said when on the throttle either cruising or accelerating. The pump is designed to mostly close down on decel, some say to help clean the plugs.

I notice a real lean reading when I come off throttle.

[thehackmechanic]

Got it, thanks. But on, say, highway driving, keeping up with the ebb and flow of traffic, 55 to 65, slight speed up and slow down, does it stay in the narrow range you quoted?

[Guest Anonymous]

afr will only stay steady when throttle its steady.

Lift throttle shuts down fuel, pistons still piling in lots of air.....lean.

Accel is opposite.

[BillWilliams]

I will check again Rob. But I think so. need to verify.

Me thinks if all is equal, the air and fuel dump in on acceleration. But what do I know. Let me check this week and get back.

But I am confident I usually go lean on decel, it is a function of the Kuglesfischer.

If you can get an audience with Dave Redsus on these issues, he will amaze you, at least he did me. He has talked to me for many minutes on the operation of the Kugelfischer. Either big or little Dave are delights but they "suffer no fools". Once you pretend to know more than them, conversation over. Nothing wrong with that. I think it is a matter if you do know more than them, don't call and waste their time.

Let me know if you want their TN.

[jgerock]

The needle on my analog AEM brand gauge will react to the the slightest change in the accelerator pedal. Will be lean when you let off the gas. It is very sensitive.

Also interesting to watch the needle when car is not running but ignition "on", powering the gauge and sensor for short periods. If wind blows across the tail pipe, the needle will react.

[thehackmechanic]

All:

Can you give me an idea how much the needle swings when, say, trying to average 55 to 65? Is it going from 13 to 15? Staying between 14 and 15? Or swinging like mine from 12 to 16?

Bill, I knew big Dave Redszus from when he would occasionally write Roundel articles, but that was 20 years ago.

[jgerry2002]

Bill, Justin, Jim, that's you :^)

Justin, you described idle around 13, WOT around 13.5, and cruising around 15.5. Does it live within those goalposts or does it swing outside them on partial loads?

Thanks.

--Rob

Idle is a tad happier at high 12s, 12.9-13.1. WOT is now 13.0. Cruise varies, but light load i am around 15.

Lifting off the throttle it will go very lean. That's normal. Any acceleration (light or heavy) will pretty much stay within this range. Decceleration there is other variables at play.

Also one of the big things that I noticed this year was when i had an exhaust header crack (3 of them), my overall mixture was lean, except at WOT. Lots of backfiring as well when i had the crack in the exhaust. Much better with a new stock header now. Idle is now fairly steady (within a couple of tenths) as opposed to bouncing all over the place.

[M3M3]

All:

Can you give me an idea how much the needle swings when, say, trying to average 55 to 65? Is it going from 13 to 15? Staying between 14 and 15? Or swinging like mine from 12 to 16?

12-16 or more is normal for highway throttle variations

kfish is ancient tech. on accel, fuel pours in richening mixture and it takes a bit for engine to suck in air to match.

decel is opposite.

lift throttle completely at speed and afr could go to 20+

steady throttle readings are what is important.

(mlytle2)

[jgerock]

lift throttle completely at speed and afr could go to 20+

steady throttle readings are what is important.

(mlytle2)

My gauge jumps to about 16-18. I now only look at steady and WOT readings knowing that it is so sensitive. SO MUCH better to read a gauge than guessing at the KF system! Best $ I spent on the car IMO.

[thehackmechanic]

Perfect. Thanks guys. I'm not as far out in left field as I thought.

[M3M3]

you can ignore the "racy" theme of this video, but it is good demo of what afr can do. digital gauge on dash is AFR. you can see when i am WOT (12.x) part throttle (14.x) and when i lift to shift or brake (big numbers lean). this is with a computer doing live corrections to fuel flow based on AFR, RPM and throttle position.

[Colin]

Does the pump cut fuel all the way on decel on a Tii?

[ray_]

Marshall's tii is a little modified. ;-)

But the reading range holds true.

Cheers,

you can ignore the "racy" theme of this video, but it is good demo of what afr can do. digital gauge on dash is AFR. you can see when i am WOT (12.x) part throttle (14.x) and when i lift to shift or brake (big numbers lean). this is with a computer doing live corrections to fuel flow based on AFR, RPM and throttle position.

[bnam]

Here's a graph that I found in a reference text which gave me a better idea on AFR ratios vs. throttle opening (air flow)