Removing the auto stop inhibitors

[RobertSmalls]

As we all know, the Insight has a long checklist of criteria, all of which must be met before the car will do an idle stop. As a result, auto stop is unpredictable, seemingly fickle, and therefore annoying.

The list includes a few inhibitors that are easily gotten around. The ambient temperature sensor has to read above ~-5°C. Proposed remedy: wire a 2kOhm resistor in paralell with, or in place of, the ambient temperature sensor. That'll make the car think it's around 25°C out. If your car has manual climate control, there's no reason not to leave it in year round.

The climate control has the authority to inhibit auto stop, and it will do so if you've selected defrost, A/C, or if you've failed to hit ECON since the last time you hit defrost. This is annoying, and not necessary if you understand that the engine won't produce or circulate heat unless the engine is turning. The climate control panel sends the signal HTRS to the ECU. See FSM p 11-170 for why I think shorting ECM A32 to ground would permanently send the signal "heater control says it's okay to auto stop". Am I reading that correctly?

There are other preconditions for auto stop. Coolant temperature must be over 40°F, or even higher if the car thinks it's winter. You probably don't want to lie to the ECU about the coolant temperature, because that figure is also used for fuel injection / ignition calculations.

The most stubborn condition, and the reason most modders have given up on auto stop, is the vehicle speed condition. Vehicle speed must be below a certain threshold, and falling. I'm sure there have been other threads on high speed auto stop, but did any of them try cutting the VSS signal to the ECU (but not the speedo, MIMA, or anything else) when the neutral safety switch has been closed for more than 2 seconds? That would seem like a pretty good indication that the driver intends to coast and the engine is not required.

I'm going to replace my ambient temperature sensor with a 1K resistor (40°C!) tomorrow, commute like that for a week, and report back. Any thoughts on the rest of the suggestions, especially spoofing the HTRS signal?

[red1dr]

I just use the FAS switch on MIMA and it bypasses a lot of these variables: various temperatures, speed. I'm not sure about AC because I rarely use it. If the IMA battery is low or if the brake booster vac is low the engine will restart immediately.

With the FAS switch on the front of my shift lever, it's very natural to FAS as I shift to neutral to begin coasting (to a stop or on a downhill). So I hardly think about it.

Maybe I'm missing something???

[joecvt]

Originally Posted by RobertSmalls

The ambient temperature sensor has to read above ~-5°C. Proposed remedy: wire a 2kOhm resistor in paralell with, or in place of, the ambient temperature sensor. That'll make the car think it's around 25°C out. If your car has manual climate control, there's no reason not to leave it in year round.

Since the year 2004, I have moved my air sensor from the front bumper area to mid engine (mounted where the MAP sensor is) using the same screw as the MAP sensor with a home made aluminum bracket. I can get AutoStop even below freezing temps (once the engine warms up enough).

Originally Posted by RobertSmalls

The climate control panel sends the signal HTRS to the ECU. See FSM p 11-170 for why I think shorting ECM A32 to ground would permanently send the signal "heater control says it's okay to auto stop". Am I reading that correctly?

My service manual must be different compared to yours (possibly due to different years - mine is from 2000-2003) so I'm not sure what you are checking on that page but another description of that signal in my book just says pulses in the area of the book that shows all connections to the ECM. Perhaps you can post an image of that page.

Originally Posted by RobertSmalls

There are other preconditions for auto stop. Coolant temperature must be over 40°F, or even higher if the car thinks it's winter. You probably don't want to lie to the ECU about the coolant temperature, because that figure is also used for fuel injection / ignition calculations.

You are probably correct into not wanting to modiy the coolant temp going into the ECM.

Originally Posted by RobertSmalls

The most stubborn condition, and the reason most modders have given up on auto stop, is the vehicle speed condition. Vehicle speed must be below a certain threshold, and falling. I'm sure there have been other threads on high speed auto stop, but did any of them try cutting the VSS signal to the ECU (but not the speedo, MIMA, or anything else) when the neutral safety switch has been closed for more than 2 seconds? That would seem like a pretty good indication that the driver intends to coast and the engine is not required.

My Low Speed Auto Stop circuit sends a fake VSS signal only to the ECM by cutting the ECM wire and replacing the VSS signal with a 9MPH signal fo a couple of seconds. I know that you want to send a different signal but it is possible. I only needed to send a 9MPH signal automatically after coming out of AutoStop (using ENGRDY signal to automatically reset the circuit) to fake the ECM into thinking that you already exceeded the 8MPH limit (even if you only went 4MPH) into going into another AutoStop.

This circuit as designed is more useful for CVT models (even the GEN2 Insights) but the idea of VSS manipulation is about the same.

Using the neutral switch as an automatic timer reset, if enabled for 2 (or more) seconds, use two 555 timing circuits (556 dual timer);

One circuit to charge a capicitor that will end up resetting the 556 chip if allowed to charge for the 2 second time period while the neutral switch is engaged.

One half of the 556 to have a circuit to operate a relay that will replace the VSS signal to the ECM for about 2 more seconds.

The other half of the 556 to have a circuit to set the initial speed at 20MPH then drop to 19MPH, then 18MPH and so on for the 2 second span of the relay activation.

This should fake the ECM into thinking that you are coming to a stop and IIRC, the MT model begins its AutoStop at 19MPH (compared to the CVT 4MPH).

This circuit does seem possible but it seems to complicate things perhaps more than you want compared to just using the current (and apparently proven) method of the FAS mod.

Hope that helps,

JoeCVT = Just your average CVT owner

[RobertSmalls]

Red1dr and others are right to wonder what the point is, when FAS is satisfactory. The answer is automation and ease of use. Sure, hitting the FAS button is easy to do, but why does it require a button at all?

I thought of a better condition than three seconds in neutral. Any time the clutch is out and the car is in neutral, you want the engine to stop by itself, and be ready to re-start when you tap the throttle.

Joe, if I understand correctly, the VSS outputs a pulsetrain with n pulses per revolution of the tire. There is one VSS signal I can emulate with just a relay, no 555 needed: 0mph. I just hope the ECU doesn't actually need the VSS for anything important, so that it can live without the signal until you shift into gear or step on the clutch.

That would make P&G really easy, eh?

[red1dr]

I see what you mean by automation but not ease of use. FAS is incredibly easy with the joystick positioned where I have it. My index or middle finger is already on the joystick ball as I shift to neutral, so all I have to do is squeeze when I want to FAS and NOT squeeze when I'm just shifting gears.

Manual FAS also saves the 3?? seconds for an automatic system to recognize that I'm not just shifting gears. Not a huge deal, but 3 seconds might be a significant fraction of some of the shorter FAS's I do.

STM that time in neutral would be a good detection method for an automated system if one were going to develop one. Shifting to neutral and NOT wanting to turn off the engine (for an engine-on glide) would be rare for me I think. Only situation I can imagine is for a very short glide where I don't want to use the additional battery power needed to re-light the engine.

Using clutch-up in neutral as a signal for an automated system might be a problem, at least for me. I often double-clutch (on both up- and down- shifts) to save wear, so having the injectors shut down when I let the clutch up in neutral would cause at the least a stumble during a double-clutch (it takes several seconds for the engine to die after the injectors are shut down).

[joecvt]

Originally Posted by RobertSmalls

Joe, if I understand correctly, the VSS outputs a pulsetrain with n pulses per revolution of the tire. There is one VSS signal I can emulate with just a relay, no 555 needed: 0mph. I just hope the ECU doesn't actually need the VSS for anything important, so that it can live without the signal until you shift into gear or step on the clutch.

The VSS is pulses of 0V and 5V....

The ECM does use the VSS for a decision of assist but that would not be a problem for what you want to do.....If you use a relay to "cut" the VSS completely to the ECM while still traveling, you may get a check engine light for lack of VSS signal if disconnected for too long.

The lack of a signal may not represent 0MPH because at 0MPH, the VSS voltage is either 0V or 5V but the ECM may expect ground or 5V (not a cut wire).

The VSS also goes to the climate control so any confusion of the ECM seeing 0MPH and the climate control "thinking" much higher may cause confusion in the communication between the ECM and climate control.

Not harm in trying the 0MPH effort by using the relay though.

I tend to do these tests in the Spring / Summer cause it's too cold outside nowadays

JoeCVT = Just your average CVT owner

[MN Driver]

Do you also need to add the brake signal to trigger auto stop?

[joecvt]

Originally Posted by MN Driver

Do you also need to add the brake signal to trigger auto stop?

Yes....that one would need to be included as well.....Seems we forgot about that one earlier

Robert, how about making the current FAS mod kick in automatically when you shift into neutral and leave the clutch out instead of getting around all of the other hassles. That way, it is still automatic. For those that double clutch, how about an option for FAS to automatically kick in 1 second after being in neutral and clutch pedal released.

It seems like less work overall and you will get automatic enablement.

JoeCVT = Just your average CVT owner

[RobertSmalls]

But no blinking green light on the dash! I'll go drive for a while and think about it. Btw, I suspect that during Auto Stop, a pulse of regen is applied to bring the engine to an immediate halt. With FAS, you have to press and hold.

[joecvt]

Originally Posted by RobertSmalls

But no blinking green light on the dash!....

I know how to make it blink I know that you are joking but if you really wanted to:

The ENGRDY wire goes from the ECM to the gauge cluster and the climate control. It goes to ground while in AutoStop so part of your FAS relay setup could be to have another relay cut the ENGRDY from the ECM and ground it at the relay so the ECM does not get ground but the cluster and climate control do. Then turn the relay off when coming out of AutoStop. That should make the light blink on the dash and perhaps turn off the climate control while in FAS.

JoeCVT = Just your average CVT owner