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Old 06-07-2008, 05:11 AM   #1
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Question EOC not working for me?

I've been driving down the interstate practicing engine-off coasting (EOC) in my automatic Honda Civic, but I don't think its doing me any good in terms of fuel economy.

I first have to shift into Neutral and then cut the engine off. I frequently forget to switch the electronics back on immediately (might be some source for less mpg) but the biggest problem is that when I start the engine back up at the bottom of a hill, I have to shift back into Drive while going around 60mph. This causes massive engine braking in order to adjust to the RPMs. I'm assuming this might take more gas and speed loss than just coasting with the engine on.

Is this happening to anyone else? How do you deal with this? I was thinking of just using DFCO (deceleration fuel cut off) and not even dealing with Neutral so that I don't get that engine braking once I get back into Drive. So far, the only practical use for EOC in my automatic seems to be when I know I'm going to park in a certain spot.
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Old 06-07-2008, 05:33 AM   #2
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I think you should not try EOC in an automatic. The transmission requires the primary pump to be working for lubrication and other transmission functions.

I believe you can damage your transmission this way.

I have used neutral coast with rev matching in a Toyota AT and it seemed to work OK. As far as long term effects and possible transmission damage, I can't tell you what would be the results.

Just my opinion

regards
gary
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Old 06-07-2008, 06:05 AM   #3
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I am driving an 89 accord with AT. I have to watch the tach on the startup. It revs up initially, then steps down partially, then it drops to idle. This takes about 3 maybe 4 seconds. If I watch, when it begins its drop to idle I shift into D and it is smooth. I think it has something to do with vacuum pressure, but I am not sure.
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Old 06-07-2008, 07:03 AM   #4
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Do not EOC an automatic unless your car's manual says it can safely be flat-towed behind an RV.

Please do not forget to turn the key back to "On" after killing the engine. Besides causing the odometer not to record your miles (and therefore getting no MPG increase in your calculations), it also means various accessories may not work, and does your steering wheel lock?

Neutral coasting with only accidental rev-matching works great in my automatic GMC, but you may need to purposely rev-match if your transmission doesn't behave the same. By accidental, I mean that I'm too impatient for it to completely engage 4th gear and I sometimes begin to step on the gas as soon as I see the tach jump up. It seems to go into 3rd gear first, I'm not sure why.
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Old 06-07-2008, 09:56 AM   #5
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I did not try eoc with my 94 intrepid automatic, i just put in neutral and drafted as much as possible with p&g and went 57 to 62 mph. I think the most fe can be had doing this while drafting. I got 32mpg from the previous 16 mpg on the gauge. The 32 mpg was freeway with the ac on. I have use the car for short trips and get 25 mpg overall. My gears may be higher as i had not problem with rev matching when shifting from neutral to drive.
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Old 06-07-2008, 12:30 PM   #6
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hm...it seems like i should probably not try it anymore, as i can't afford for the car to take any unnecesary damage...

My steering wheel doesn't lock when i turn off the engine, but it gets really hard to take sharp turns, even when i turn the electronics back on.

Rev matching is kind of tough for me...i don't have a tachometer so I'd be blindly hitting the accelerator.
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Old 06-07-2008, 12:56 PM   #7
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Especially with an automatic, rev-matching needs only be vaguely approximate. If the car jerks forward you overdid it. If the car bucks back you didn't do enough.

Either way, you definitely should not EOC.
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Old 06-07-2008, 02:52 PM   #8
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Ok, here is a question on Neutral coasting, the owner manual says not to tow on all four wheels but can be towed on drive wheels as long as the car dose not go over 55. Is this ok for Neutral coasting?

OM
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Old 06-07-2008, 03:23 PM   #9
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Yes. The difference is that the engine is on, so the transmission is still being cooled by its oil pump (which I think runs off the transmission's input shaft).

In fact, considering what the manual says, you should be fine for EOC under 55mph, and probably at any speed (since the 55 number is probably there for liability issues due to handling/stability while being towed). Does it say whether that can only be done for emergencies, or does it say you can do it with an RV?
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Old 06-07-2008, 03:34 PM   #10
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Quote:
Originally Posted by theholycow View Post
Yes. The difference is that the engine is on, so the transmission is still being cooled by its oil pump (which I think runs off the transmission's input shaft).

In fact, considering what the manual says, you should be fine for EOC under 55mph, and probably at any speed (since the 55 number is probably there for liability issues due to handling/stability while being towed). Does it say whether that can only be done for emergencies, or does it say you can do it with an RV?
It only list it as emergency toeing, nothing about RV towing at all. The manual dose not go into that kind of detail. The Service manual offers nothing either.
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