Bad fuel economy ...
03-Feb-2007, 11:23 PM
#1
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Join Date: Mar 2004
Location: Hamilton
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Bad fuel economy ...
What are some of the general reasons for poor fuel economy in hondas? I went trough some of the helm manuals and there's no help at all
I've never had such bad fuel economy in my EF with B16. I'm down about 30%. This was even before the cold spell. The car runs rough when cold.
So far, I checked:
Plugs are fine,
Ignition cap, rotor is new.
Ignition wires are fine (worst one is #1, the longest at 12K ohms)
New Oxygen sensors.
Could the ignition coil be failing? I thought though that when coil fails, it completely fails.
I've never had such bad fuel economy in my EF with B16. I'm down about 30%. This was even before the cold spell. The car runs rough when cold.
So far, I checked:
Plugs are fine,
Ignition cap, rotor is new.
Ignition wires are fine (worst one is #1, the longest at 12K ohms)
New Oxygen sensors.
Could the ignition coil be failing? I thought though that when coil fails, it completely fails.
04-Feb-2007, 02:17 AM
#3
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Join Date: Mar 2005
Posts: 6,176
^^ did you even read his post at all...
Anyways, what did the plugs look like? How did you determine they were fine?
Could be anything under the sun, bad ignition timing, fuel filter, cloged cat, air filter, poor alignment, poor tires pressures, leaking injector, etc.
It would help if you could tell us some symptoms you are having (if any). ex would be cold starts, does it bog? does your low-end power feel weaker than regular? does it misfire up top? stuff like that.
Anyways, what did the plugs look like? How did you determine they were fine?
Could be anything under the sun, bad ignition timing, fuel filter, cloged cat, air filter, poor alignment, poor tires pressures, leaking injector, etc.
It would help if you could tell us some symptoms you are having (if any). ex would be cold starts, does it bog? does your low-end power feel weaker than regular? does it misfire up top? stuff like that.
05-Feb-2007, 10:13 AM
#4
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Spark plugs are new, new Cat converter, timing is stock, air filter looks good, I think fuel filter is ok but I'm not sure.
I'm thinking that it's ok as my fuel pressure guage reads the same pressure.
My main problem is poor fuel economy.
Cold starts are rough, the car always dies. It also appears like not all cylinders are working as the idle is rough. I'm pretty sure that the main reason for that is too low of idling RPM. The car takes a min or 2 to kick in with higher idle (about 2000 RPM).
How do I check the ignition coil? I thought that when they are bad, they die. (sort of like igniters)?
I'm thinking that it's ok as my fuel pressure guage reads the same pressure.
My main problem is poor fuel economy.
Cold starts are rough, the car always dies. It also appears like not all cylinders are working as the idle is rough. I'm pretty sure that the main reason for that is too low of idling RPM. The car takes a min or 2 to kick in with higher idle (about 2000 RPM).
How do I check the ignition coil? I thought that when they are bad, they die. (sort of like igniters)?
05-Feb-2007, 02:00 PM
#5
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Join Date: Mar 2005
Posts: 6,176
well when it's idling rough.
Pull out one spark plug wire at a time and see if the idle changes dramatically. For every single plug wire you remove.. the idle should really change. If it doesn't, you know you have a bad cylinder (weither it be injector, spark, w/e)
An ignition coil normally shows sign of failure under more warm temperature's, I wouldn't go diagnosising it yet. But I suppose you could. Do a search here on how to diagnosis a coil, i'm pretty sure i've explained it before, if you cant find it, i'll explain it again.
Pull out one spark plug wire at a time and see if the idle changes dramatically. For every single plug wire you remove.. the idle should really change. If it doesn't, you know you have a bad cylinder (weither it be injector, spark, w/e)
An ignition coil normally shows sign of failure under more warm temperature's, I wouldn't go diagnosising it yet. But I suppose you could. Do a search here on how to diagnosis a coil, i'm pretty sure i've explained it before, if you cant find it, i'll explain it again.
05-Feb-2007, 02:53 PM
#6
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Location: Pickering
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Generally in a honda, if a cylinder has failed due to compression loss, the idle will be VERY Rough and the car usually will not be able to keep itself alive @ idle once it's warmed up. I think a honda can keep running if 1 cylinder still has compression but no fuel or spark going into it
Do what Chris says. If you pull a wire and the idle does not change you know that cylinder is at fault. Maybe then ensure a spark is coming out of each plug.
Do what Chris says. If you pull a wire and the idle does not change you know that cylinder is at fault. Maybe then ensure a spark is coming out of each plug.
05-Feb-2007, 03:02 PM
#7
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Posts: 6,176
^^ to ensure that it's sparking when you remove the plug wire ground it on the valve cover.. you will hear a slight ticking (spark gapping) that is a quick test to determine weither is spark or fuel.
Cablerat is right about the compression loss, that's another thing you could investigate. When the engine is warmer it 'swells' so compression is stronger than when it's cold.
Cablerat is right about the compression loss, that's another thing you could investigate. When the engine is warmer it 'swells' so compression is stronger than when it's cold.
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