How much fuel does turning the car on consume?

[KARR]

Sorry for asking but what is the "ICE"?

[LxMike]

Originally Posted by KARR

Sorry for asking but what is the "ICE"?

Internal
Combustion
Engine

[Bennet Pullen]

Originally Posted by Telco

Two, the manufacturer thinking on the start/stop at stoplights is through engine control. These systems won't use the starter to restart the engine, the computer keeps track of the crank location and will fire whatever cylinder is set at TDC on the compression cycle. The idea here is to let the engine start itself. No idea how long the car can sit before it has to be restarted manually. Eventually the manufacturers hope to do away with the starter altogether and just use engine firing to get the car started, but I seriously doubt they will ever get it to work as there are instances where all cylinders are positioned to where they would not be able to fire one with enough force to turn the engine over.

Here is some info on the start/stop system BMW is starting to use. It is just using a conventional starter.

http://www.autoblog.com/2007/03/26/b...-bmw-1-series/

[MetroMPG]

GM uses their alternator/starter in their BAS cars. All the full hybrids also currently use a motor to refire the ICE.

So far the only manufacturer I'd read about using just ignition to refire the ICE was Mazda...

Mazda’s New Smart Idling Stop System for Direct-Injection Spark-Ignition Engines

Mazda is displaying a new form of an idle-stop system for direct-injection spark-ignition engines that uses combustion and the reverse operation of the engine as a restart trigger rather than an electric motor.

http://www.greencarcongress.com/2005..._new_smar.html

[omgwtfbyobbq]

Originally Posted by Ryland

unless you are holding your foot down on the accelerator pedal as you crank the engine over, it should be injecting the same amount of fuel in on each rotation as it gets when it's idling.

I just got this awesome book on diesels and apparently, VE IPs inject roughly 2-3 times the fuel they do when idling for startup. Not that it matters much, since turning the engine off for more than 3 seconds at a time will still save fuel, but I just figured I'd put that out there.

[trebuchet03]

Originally Posted by omgwtfbyobbq

I just got this awesome book on diesels and apparently, VE IPs inject roughly 2-3 times the fuel they do when idling for startup. Not that it matters much, since turning the engine off for more than 3 seconds at a time will still save fuel, but I just figured I'd put that out there.

Out of curiosity, is there a difference between a hot start and a cold start? Just curious

[DRW]

A few curiosities I've found in the ecu disassembly for my car is that there is extra enrichment on startup for all coolant temps. So there's a 'choke' function even when the motor is fully warm. Startup enrichment is much lower at warmer coolant temps, plus there's a two stage countdown timer that decreases startup enrichment quickly at first, then slower. The warmer the engine is, the quicker it counts down and reaches normal enrichment.

I have a feeling this is because port fuel injection systems rely on a hot intake valve to help atomize fuel. When the motor is first started and when it's cold the intake valve is also cooler, so more fuel is needed so that enough fuel becomes atomized enough for good combustion.

Another curiosity is that the ecu doesn't know which cylinder is at TDC until the motor rotates at least one turn, sometimes a little more. Since the intake stroke begins one turn before the spark is fired the ecu deals with this by firing all injectors at once in hopes that one cylinder will catch fire when the first spark is signaled. The other 3 cylinders vent wasted fuel, although only about a grams worth is wasted. HTH!

[omgwtfbyobbq]

Originally Posted by trebuchet03

Out of curiosity, is there a difference between a hot start and a cold start? Just curious

I imagine it depends on the car. I haven't gotten around to anything except for thumbing through this (0768005094) but for the older mechanical VE pumps there's no change in fuel delivery AFAIR(ead), assuming the cranking time is the same of course. The manual and automatic KSB (cold-start accelerator) just advance timing for startup. There's also the TLA which increases the cold idle, but I don't think it does anything to the quantity of fuel injected on startup, and the Hydraulic cold-start accelerator which allows for a different advance curve over a range of engine speeds, unlike the other method that just advances the initial injection a set amount. I think.... EDCs can prolly change the quantity of fuel injected depending on the ECU's inputs.

[MetroMPG]

I wonder if any of this applies when the engine is clutch started, or is it only triggered via the key switch?

[omgwtfbyobbq]

I'm guessing that it's mostly a function of coolant temp, which is why block heaters help so much. Iirc, Dan(?)/krousedb also said that he would bypass most of the enriched cycle by bumping and and getting up to speed, then EOC'ing w/ an injector kill switch, since the ECU stayed on and the cycle kept winding down.