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Engine Breaking and Flat Lean AFR, Normal?

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Old 09-15-06, 12:16 PM
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Engine Breaking and Flat Lean AFR, Normal?

Hello all,

I have a habit leaving things in gear while decel, where you can used engine to slow down the car and no throttle.

Now, the Wideband tells me when I do this, the AFR is flat lean, is this ok to do then?

Thanks, car is a converted TII
Old 09-15-06, 12:18 PM
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under engine breaking there is no fuel being delivered so that would be normal.
Old 09-15-06, 12:23 PM
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I am having some puzzles to figure out. Now, say, the SAFC is connected to the boost sensor, since it is a S4, at high rpm, how the computer know that, there is no throttle which leads to no fuel?
Old 09-15-06, 12:29 PM
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Originally Posted by aGoGo
I am having some puzzles to figure out. Now, say, the SAFC is connected to the boost sensor, since it is a S4, at high rpm, how the computer know that, there is no throttle which leads to no fuel?
for the S4 if you wire the TPS from the SAFCII into the MAP sensor it will read like a normal wideband TPS system?

no shitty throttleness?
Old 09-15-06, 12:31 PM
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Originally Posted by aGoGo
I am having some puzzles to figure out. Now, say, the SAFC is connected to the boost sensor, since it is a S4, at high rpm, how the computer know that, there is no throttle which leads to no fuel?
my guess is that since the SAFC compinsates in % and 0 fuel is being delivered that your fine. also every EFI car does this so i also assume that they make the SAFC knowing this.
Old 09-15-06, 12:45 PM
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1. I wouldn't worry about it.
2. You're not supposed to engine brake, unless you think your brakes might fail on a long mountain road. Brake pads are cheaper than your clutch/engine, etc. All student drivers in Great Britain learn "Gears to go, brakes to slow." Or so some Great Britain-ite claimed.
Old 09-15-06, 12:50 PM
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Hmmm.... as far I know or used to, Japanese teaches to leave it in gear all time ...
Old 09-15-06, 12:51 PM
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I think the MAP for a NA S4 is the Boost Sensor for a TII, I am correct?
Old 09-15-06, 12:53 PM
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None of my pals leave it in gear, I never take it out(ony to shift).

I think it is safer to leave it in gear because what if someone looses control and comes flying at your driverside door. You might have that extra second to get out of the way.
Old 09-15-06, 01:17 PM
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Yes, I like the control. What about Auto-X? People got to leave it in gear, right?
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