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LoL, ok, so it's running a touch rich . . .

Discussion pertaining to positive pressure E28s.
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Jeremy
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LoL, ok, so it's running a touch rich . . .

Post by Jeremy »

Finally got my WBO2 setup out of its hiding place and back on the car today and did a few pulls before I put it back into the storage unit.

Idle = 14.4 -14.7

Cruise = 14.5 - 14.7

WOT + full boost = 10.8 :shock:

Whoopsie! Only about 85 degrees today, too. I can only imagine what it's like with temps in the upper 90s. Time to tighten down that AFM next time I have the chance.

Kinda explains why it felt kinda doggish on full throttle boost in hot temps, eh? lol

Jeremy
Kyle in NO
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Post by Kyle in NO »

Should be a function of your FMU rather than the AFM under WOT correct?
Jeremy
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Post by Jeremy »

FMU is already dialed all the way out on both adjustments. Apparently I never cranked down the AFM spring enough to begin with.

Jeremy
Boru
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Post by Boru »

Simple solution... increase boost :o)
turbodan
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Post by turbodan »

Sweeney wrote:Simple solution... increase boost :o)
Definitely.

Or add a restrictor in the FMU feed line. I remember the difference that made in my application back when I was still running the FMU. Its was like WHAM. Good stuff.
landspeed
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Post by landspeed »

Jeremy wrote:Apparently I never cranked down the AFM spring enough to begin with.

Jeremy
You tighten the afm screw to lean it out right?
turbodan
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Post by turbodan »

landspeed wrote:
Jeremy wrote:Apparently I never cranked down the AFM spring enough to begin with.

Jeremy
You tighten the afm screw to lean it out right?
That would richen the mixture. Or were you kidding.
Jeremy
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Post by Jeremy »

Sweeney wrote:Simple solution... increase boost :o)
Increasing boost on the bed of an imperfect tune has been done before. It's solidly in the "bad idea" column in my book.
landspeed wrote:You tighten the afm screw to lean it out right?
You mean the bypass screw? I leave that alone generally. You tighten the AFM spring itself by turned the toothed wheel. This increases the spring preload, which causes the flap to open less for the same volume of air. This, in turn, will decrease the injector duty cycle for that volume of air, thus leaning out the AFR.

It's an imperfect way of doing things as you're also messing with the timing curves by changing the spring tension, but it works reasonably well.

Jeremy
///ARINUTS...
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Post by ///ARINUTS... »

Jeremy wrote:FMU is already dialed all the way out on both adjustments. Apparently I never cranked down the AFM spring enough to begin with.

Jeremy
That doesn't make sense. if you have it dialed out on both adjustment and you are running too rich, dial it back in.

I am assuming that you are using an adjustable FMU.

If not, then change the ratio disc, if its 12:1 try a 10:1, or if 8:1 , try a 6:1.

Get the idea?
Boru
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Post by Boru »

Jeremy wrote:
Increasing boost on the bed of an imperfect tune has been done before. It's solidly in the "bad idea" column in my book.

Jeremy
Only when the end result is detonation. You have a way to go before it detonates.
turbodan
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Post by turbodan »

///ARINUTS... wrote:
Jeremy wrote:FMU is already dialed all the way out on both adjustments. Apparently I never cranked down the AFM spring enough to begin with.

Jeremy
That doesn't make sense. if you have it dialed out on both adjustment and you are running too rich, dial it back in.

I am assuming that you are using an adjustable FMU.

If not, then change the ratio disc, if its 12:1 try a 10:1, or if 8:1 , try a 6:1.

Get the idea?
He has it on the minimum gain setting is what he's saying. That seems to happen with BMW turbos and the BEGi regulator. I needed to install a restrictor for mine to work properly.
Jeremy
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Post by Jeremy »

Restrictor is in the signal line already.

Sweeney, I follow the logic, but remember that I'm also opening the flap all the way at >5k rpm and Motronic goes to max duty cycle when that happens. Increasing the boost level will make that happen sooner. Cranking down the spring should fix that and the richness over the rest of the range at the same time.

Least that's what I'm hoping for.

Jeremy
landspeed
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Post by landspeed »

turbodan wrote:
landspeed wrote:
Jeremy wrote:Apparently I never cranked down the AFM spring enough to begin with.

Jeremy
You tighten the afm screw to lean it out right?
That would richen the mixture. Or were you kidding.
Just curious really, I generally don't like to mess with the factory settings either, but it doesn't hurt to ask right?
j9fd3s
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Post by j9fd3s »

just a thought, cause your cruise and idle mixtures are right on...

the 84-85 rx7's with efi, have a stop screw on the afm, its actually spring loaded so the door cant slam open.

but its adjustable, and this gives you adjustment for the WOT mixture, a little. if the bmw one, doesnt have it, its really really simple to add, all you need is a drill, tap, bolt and jamb nut.

http://www.jimrothe.com/mazda/afm_project/index.html

you can see it in the 1st pic.
turbodan
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Post by turbodan »

The AFM in e28's does not have that adjustment. I wouldnt alter spring tension unless the cruise and idle AFR's are out of whack. That adjustment will lean it out at cruise and idle. Thats not what you want here. Those are great. The RRFPR handles boost, and under boost is where the problem exists, so I would make that work. More boost would be an acceptable solution to me. Next up is an inline restrictor small enough so you have some adjustment to go eithyer richer or leaner than where it likes to be. I dont like being all the way in or out.

Its like jetting. My kawasaki has an air screw that works with the pilot jet. If you're all the way it, and it still doesnt work, you need a different pilot jet. Consider the inline restrictor your pilot jet.
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Post by j9fd3s »

turbodan wrote:The AFM in e28's does not have that adjustment. .
adding it would be really easy, its not a good picture.

if thats what yer talking about :D
Skeen
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Post by Skeen »

Assuming he's running closed loop, won't Motronic keep cruise near stoich even if he leans it out for WOT?
turbodan
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Post by turbodan »

Skeen wrote:Assuming he's running closed loop, won't Motronic keep cruise near stoich even if he leans it out for WOT?
If it isnt already against the mixture adaptation threshold. And only if the same amount of adaptation would be suitable for idle and cruise. If its leaner at idle than cruise than it will be constantly adjusting back and forth. The O2 correction is not fast enough to avoid running rich on roll on and lean as it dipped back to idle. That would bother me.
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