Fuel Cut-Off - How do we optimize it?

[Larry]

That's what I changed to copper plugs, they can handle much higher gap due to their conductivity.

|Metal|| ||Melting Point|| ||Electrical Conductivity|| ||Thermal Conductivity||
||Copper|| ||1083 C|| ||.596 x 10^6|| ||400 W/(m K)||
||Platinum|| ||1768 C|| ||.0966 x 10^6|| ||72 W/(m K)||
||Iridium|| ||2410 C|| ||.197 x 10^6|| ||150 W/(m K)||

 

[ChrisJ]

That's what I changed to copper plugs, they can handle much higher gap due to their conductivity.

|Metal|| ||Melting Point|| ||Electrical Conductivity|| ||Thermal Conductivity||
||Copper|| ||1083 C|| ||.596 x 10^6|| ||400 W/(m K)||
||Platinum|| ||1768 C|| ||.0966 x 10^6|| ||72 W/(m K)||
||Iridium|| ||2410 C|| ||.197 x 10^6|| ||150 W/(m K)||

I may be wrong here but my assumption is it has far more to do with the air in the gap than the conductor.

I somehow doubt a few inches of metal really matters when you're dealing with 20-50kv.

 

[Larry]

I may be wrong here but my assumption is it has far more to do with the air in the gap than the conductor.

I somehow doubt a few inches of metal really matters when you're dealing with 20-50kv.

Doubt is the biggest compliment one can be given, thank you.

 

[ChrisJ]

Doubt is the biggest compliment one can be given, thank you.

Let's just wait and see what others say before you go taking compliments.

 

[Larry]

Let's just wait and see what others say before you go taking compliments.

Don't take it so personally. I'm just having fun

 

[ChrisJ]

Don't take it so personally. I'm just having fun

Me too.

Until I find out I'm wrong.

 

[Larry]

Me too.

Until I find out I'm wrong.

I may be wrong, but I'm pretty damn confident that these new plugs made a big difference. cruzetalk has a lot of users posting the same results.


http://www.cruzetalk.com/forum/34-1-4l-turbo/29881-ngk-bkr7e-4644-gap-tune-thread.html

 

[ChrisJ]

I may be wrong, but I'm pretty damn confident that these new plugs made a big difference. cruzetalk has a lot of users posting the same results.


NGK BKR7E-4644 gap/tune thread

I can't look there right now but the more I think about it.
Don't spark plugs even have a built in resistor to add resistance to the plug suggesting the resistance of the tip is even more meaningless?

 

[Larry]

I can't look there right now but the more I think about it.
Don't spark plugs even have a built in resistor to add resistance to the plug suggesting the resistance of the tip is even more meaningless?

You're misunderstanding. Its not providing more spark, itsa allowing the requested spark to actually happen. Think of the way breather mods work on cars. Exhaust doesn't add horsepower, it just has less restriction.

Wider gap means more complete fuel burn, which is better for efficiency and power.

 

[ChrisJ]

You're misunderstanding. Its not providing more spark, itsa allowing the requested spark to actually happen. Think of the way breather mods work on cars. Exhaust doesn't add horsepower, it just has less restriction.

Wider gap means more complete fuel burn, which is better for efficiency and power.

Ok.
However a wider gap combined with high boost often ends in blowout. No? How is a copper tip stopping this? You said before it was due to lower resistance.

I know without a doubt a wider gap (to an extent) is better. I just don't see how you're getting consistent performance under boost is all. Maybe copper untipped plugs are better. One thing I can agree with is changing them every 30K on the 1.4 isn't an issue as its so easy. All of my previous engines were either V6 or V8 and were awful to change usually ended up with cut arms and hands from shields jammed into areas.

 

[Larry]

Ok.
However a wider gap combined with high boost often ends in blowout. No? How is a copper tip stopping this? You said before it was due to lower resistance.

I know without a doubt a wider gap (to an extent) is better. I just don't see how you're getting consistent performance under boost is all.

I had blowout at 0.035", so I lowered it to 0.032". Copper has less resistance, so the spark can travel over a wider distance. I'm not sure how else to explain it.

See in the diagram, the resistor is not anywhere near the ground strap or center electrode. That's where the less resistance comes into play, not at the resistor.

 

[ecohauler]

Back on topic here, something I didn't consider that seems to be important is catalyst temperature. It seems that when my engine's warmed up and I'm cruising around gently, I can't get into DFCO at all, but if I gun it for a few seconds, DFCO happens more or less as it should. I think for emissions reasons our ECU wants the cat above a certain temp before it will cut fuel. This seems to be the most consistent correlation I've found. For this reason, I think wrapping the upper exhaust is going on my short term to-do list.

I think this was mentioned in another thread a little while back, but I haven't seen it in this thread.

 

[sx sonic]

Question for any of you auto trans folks with an UltraGauge, ScanGauge, or Torque App that can monitor instantaneous fuel economy.

How often does the auto go into DFCO, if at all?

 

[Larrymer]

...

 

[KPM]

Question for any of you auto trans folks with an UltraGauge, ScanGauge, or Torque App that can monitor instantaneous fuel economy.

How often does the auto go into DFCO, if at all?

I just got my UlreaGauge this week.

How can I tell when it goes into fuel cut off ?

 

[Stew]

I just got my UlreaGauge this week.

How can I tell when it goes into fuel cut off ?

Set instant MPG as one of your gauges, when it reads 999 you're in DFCO. The RPM range is pretty narrow, without double checking I believe it's while coasting down from 1800 down to 1400.

I seem to remember you also have to set DFCO in the Ultragauge too, it was set to not acknowledge it by default.

 

[KPM]

OK, Thanks Stew.

I do have one of the big displays on my UltraGauge set to instant MPG. And I have seen it flash to all 9's at times.

I think I've seen it mabey two or three times in the 4 days I've had the UltraGuage, 280 miles.

 

[Breezybro]

OK, Thanks Stew.

I do have one of the big displays on my UltraGauge set to instant MPG. And I have seen it flash to all 9's at times.

I think I've seen it mabey two or three times in the 4 days I've had the UltraGuage, 280 miles.

I've had mine like a month, never seen this.

 

[Stew]

I've had mine like a month, never seen this.

You don't have injector cutoff configured in the UG then. From page 47 of the UG manual:

------------------------------------------------------------

Injector Cutoff
MENU -> UltraGauge Setup -> Injector Cutoff

While in gear during de-acceleration, many vehicle manufacturers will turn off the fuel injectors in order to save fuel. This is true for vehicles with either manual or automatic transmissions. The fuel savings is slight, but over time and distance could become significant. UltraGauge can detect when the injectors are switched off and factor the fuel savings into the fuel usage and mileage calculations.

Injector cutoff is disabled when set to zero, and is disabled by default. To enable Injector cutoff detection, set the value equal to seven times the engine size in liters, rounded up to a whole number. For example, for a 2.3L engine the value should be set to 2.3x7= 16.1  17. The value is not crucial and this calculation represents a best estimate.

When enabled and injector cutoff occurs, the Instantaneous MPG will read 999.9, and the Instantaneous Gallons/hour will read 0.0. Injector Cutoff should only be seen when de-accelerating. If during heavy acceleration, Injector Cutoff falsely occurs, decrease the injector cutoff value by 20% or until cutoff no longer occurs. Setting the value too low will cause the Injector Cutoff to never be detected.

NOTE: Injector cutoff detection should be enabled prior to performing fuel calibration. If enabled after calibration, the calibration procedure should again be performed.

NOTE: If the open/closed loop indicator is not displayed on the gauge display or the loop is always open, then the vehicle does not support Injector Cutoff detection and this feature should remain disabled. If the loop indicator is always open, this could indicate an issue with your vehicle. If so, check for the presence of trouble codes.

NOTE: Nearly all Diesel vehicles do not operate a closed loop system, and as such do not support the open/closed loop indicator. UltraGauge does not support injector cutoff for Diesel vehicles.

NOTE: Each vehicle manufacturer has their own algorithm for injector cutoff. Some require significant de-acceleration, usually enabled in terms of higher RPMs and a certain speed threshold, while others have a much lower de-acceleration requirement.

NOTE: When the transmission is placed in neutral, the vehicle’s injector cutoff function is disabled.

NOTE: This is an optional setting and provides only marginal benefit to fuel usage and MPG calculations.

 

[Breezybro]

Crap load of text

You're my freaking hero, thank you