coast in gear or in neutral?

[slowjoe]

i've been hearing quite a bit about all these new cars that shut off their fuel injectors when you are coasting in gear with your foot off the gas pedal. for them, they say it is more fuel efficient to leave it in gear than to put it in neutral. do our legacys do that?

lets say im coasting(foot off the gas pedal) down the mountain and i want to save gas and their are no cars around. what should i do?
turning off the engine cuts my power brakes, power steering and signals.
leaving it in drive with the engine on limits me to about 60mph.
putting it in neutral with the engine on lets me get to about 70mph.

[BSOD2600]

If you had a wideband installed, the question would be answered.

Coasting in neutral in unsafe. What if you need to quickly accelerate out of the way of something?

In neutral, the car idle AFR is around 14.7 in ideal conditions. When I coast in gear, the AFR drops above 20 (what the wideband can read). The ECU knows there is no load on the engine and cuts the fuel (I have data logging to support this too).

Another thing to read: http://www.revtronix.com/node/31

[Legacy777]

This is "function" is typically called Overrun Fuel Cut. Here's a blurb from the Link help file, which explains its function. The stock ECU is more than likely going to be similar/same.

The overrun condition is recognised if both the throttle is closed (throttle position less than the TPS Threshold) AND the engine speed is above the engine speed set for the current engine temperature in the Fuel Cut De-Activation RPM Table.


Setup Procedure: The De-Activation RPM must be set above the engines idle speed so that fuel is not cut when the engine is sitting at idle with the throttle closed. In practise the De-Activation RPM should be set around 500 RPM above idle so that as the engine speed falls during overrun the fuel is turned back on early enough to stop the engine from stalling. A typical De-Activation RPM for a fully warm engine (80-100 degrees C) is 1500 RPM.

When the engine is cold the idle speed control system will typically be setup to raise the idle speed. As a result, it is necessary to raise the De-Activation RPM at lower engine temperatures. Even if the idle speed is not increased during cold running it is still advisable to use larger De-Activation RPM numbers at lower engine temperatures. This is because cold engines generally do not tolerate the use of a fuel cut especially at low RPM.

[206er]

coasting in gear you can't gain speed
mexican overdrive ftw!

[slowjoe]

thanks a bunch guys.
the revtronix site is pretty kool
i was looking at THIS and i noticed that the software only supported the SS. is there anything for NA's? can i use the Subaru Select Monitor (SSM1/OBD1) USB Cable? and even if i could i'd still need software right?

[Legacy777]

You can use this

http://bbs.legacycentral.org/viewtopic.php?t=16219

[Mattheww044]

didnt he quit making them?

[BSOD2600]

is there anything for NA's? can i use the Subaru Select Monitor (SSM1/OBD1) USB Cable? and even if i could i'd still need software right?

Revtronix developer was looking for suggestions for additions to the RevScan software -- N/A cars should be fairly simple since they have the basics down now. Go ahead and ask for it on their revscan forum. Yes, you can use any cable which shows up as a COM port in Windows for the software to function. I'm actually using the EvoScan USB cable which works [mostly] fine.
EvoScan does have a wider overall feature set, but zero official support for our cars, which means its up to you/users to find the location of the ECU parameters and their conversion factors (some it will never be able to perform due to the complexity required). Revtronix people have apparently reversed engineered the ECU software and enabled a lot of cool features via their RevScan software (read/reset CEL codes, reset some ecu parameters [fuel, octane, etc], read/reset memory fuel/knock correction / count tables).

didnt he quit making them?

B10scan still works on our cars... just the 0.06 version seems to be more buggy/problematic for people instead of the older 0.05 version. It's the little juicebox stand alone scan tool device which he only made a few of, since a forum user ruined it for the rest of us...