EOCing while in gear causes rough running

[pete c]

I do a good bit of EOCing. Not much of a point to leave the ignition off though, when using the engine as a brake, or just to get my power brake vacuum back. So, I have had no issues doing it with my '05 focus ZX-3.

But, the other day, I had to drive to New Bedford, MA for work. I decided to leave the ignition off, even while engine braking, just to see how short I could make the nearly hundred mile drive. I take 44/101. This is a great 2 lane state highway for getting mileage. Lots of long downhills/uphills. After a long downhill, ignition off, in gear for engine braking, I found that I would have a low rpm stutter. It would clear its throat after about 5 miles. I repeated this a number of times and each time, the same thing.

Anyone else experience this? I have decided to stop EOCing in gear for now.

One of the reasons I did this was that I had heard a while back, that CT is looking at going to miles driven as a means to collect tax. If they carry through with this, I will be one EOCing mofo.

BTW, I was able to do the near hundred mile drive in about 70 "miles". With more effort, and lighter traffic, I think I could get it down to 50 miles.

[jedi_sol]

I think you are misunderstanding the concept behind "EOC-ing"

The point of engine braking is that, while in gear, (in most modern cars) the fuel injectors automatically shut off, however, you lose too much speed. Therefore, whatever "gains" you made with engine braking are lost because you have to speed up again. I use engine braking when i KNOW i have to slow down to an eventual stop (ie a stop sign).

Engine Off Coasting is coasting in NEUTRAL while the engine is off. This way, you get the benefit of 1) fuel injectors are turned off and 2) you're coasts are longer because you are in neutral.

I am afraid your "EOC-ing in gear" might have damaged your transmission.

[dirtydave]

so you turn the key back to kill the engine and leave it?

[jedi_sol]

I read your post like 5 times again.

So you turn the ignition off and leave the entire car off so that the odometer does not "register" the miles traveled due to the possibility of CT taxing you on miles driven?

If that's the case, then you can still turn the ignition off...but just be sure to put the car in neutral so that you don't ruin your transmission.

Also, since you are "tricking" the odometer to register less miles than actually traveled, you're not concerned with "actual" miles traveled for mpg calculation purposes?

[dirtydave]

doesn't the steering wheel lock?

[jedi_sol]

Originally Posted by dirtydave

doesn't the steering wheel lock?

I'm sure the steering does lock, but the OP says the highway has "long and gentle" hills...no mention of any corners, lol.

unless engine off coasting in gear somehow disables steering wheel lock?

[oldtamiyaphile]

I do this a lot, except I call it forced DFCO. I can see no reason why it would damage a manual gearbox. All the gearbox 'knows' is it's decelerating, it doesn't matter if it's DFCO forced by the ECU or the driver. In fact it can be better for the driveline as it can eliminate that on/off jerking as the ECU switches fuel back on at low revs.

It's a useful technique if you drive as speeds below DFCO engagement. My car glides a long way (almost as long as if it were in neutral) this way because the engine is only turning over at idle. It keep the alt charging, brake vacuum and PS pressure up.

With my Kangoo fully loaded to about 4500lbs it's little 1.6 provides so little engine braking that there's no difference at all in the rate of deceleration when I finally push the clutch in (I even asked a passenger if they could tell). Normal DFCO switches the fuel back on at 1200rpm on most petrol cars, I can go all the way to 800 or less, before switching the ignition back on, or just dipping the clutch if I still need to stop.

I use GPS to track millage since any kind of EOC will throw that off anyway.

My only concern is that if you use this technique if you do it to too low RPM (below idle) the engine oil pump might not be supplying enough pressure.

I find it a useful technique, particularly for heavy cars with small engines.

[user removed]

My 37 Ford would produce 60 psi on cold oil cranking at 100 rpm, about 1/3 of a modern engine (cranking speed). It had a push button starter with a steering lock ignition key cylinder. I would use the crank only function to pre lube the engine when it sat for a week or more.

regards
mech

[California98Civic]

Originally Posted by pete c

... After a long downhill, ignition off, in gear for engine braking, I found that I would have a low rpm stutter. It would clear its throat after about 5 miles. I repeated this a number of times and each time, the same thing.

Anyone else experience this? I have decided to stop EOCing in gear for now.
...

I really hope this is not an auto or CVT transmission.

[H-Man]

Originally Posted by California98Civic

I really hope this is not an auto or CVT transmission.

The 3 speed automatic they used in the older corollas (A131L) would not have an issue with this. My mad discovered that once you get the A131L to go into lockup the only way to get it to drop out of lockup is to slow down. It did not care if it is consuming or supplyying torque to the engine, it would keep the engine spinning at an exact multiple of the tire rpm.
Car was carbed and would backfire when turned back to on if you were coasting in gear with the ignition off.