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TDI Fuel Economy Discussions about increasing the fuel economy of your TDI engine. Non TDI related postings will be moved or removed.

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Old January 14th, 2008, 09:09   #31
DFWDieselJet
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Quote:
Originally Posted by Bob_Fout
Not fast enough in an "oh s***" situation. Most won't the presence of mind either. I won't gamble my life or those in my car for pennies.
If you're that concerned about safety, why don't you drive an automatic? The added coordination, effort, distraction, and possibility of error accompanying a manual car clearly pose added danger compared to an automatic.

Arguably this is potentially more dangerous that turning off the engine.

(BTW, I love manuals, I'm not arguing agaisnt them on safety grounds, just trying to make a point.)
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Old January 14th, 2008, 09:14   #32
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Originally Posted by VeeDubTDI
There's no way that the PD burns 3 times as much fuel at idle as the VE. Maybe if you had every single accessory on full blast. But not in most circumstances.
Well, either scangauge AND VAG-COM are wrong on PD engines, or wrong on VE engines, or it's true. And that's with no accessories, not even DRLs.

Keep in mind that at .3 gallons/hour, you could idle a PD continuously for over two DAYS. At .1 gallons/hour, thats over 6 days. Intuitively, which sounds more likely?
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Old January 14th, 2008, 09:30   #33
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I would add a #11 item to the list Aaron:

11. The importance of a good MAF airflow sensor (free of contamination) and a clean air filter can not be overstated. A contaminated MAF can drop mpg by 10%

I recently had to replace my second MAF in 8 months. Upon investigation, I found that my airfilter's seal was compromised! Dirty air was tracking in around the corner close by the MAF. This killed my MAF. I had been seeing economy drop from 49 mpg tanks to 45 mpg tanks and lower. City economy absolutely sucked. Sometimes I was seeing high 20's

I got a new airbox from a friend and loaded it up carefully with a new winter air filter and put in a new "D" revision MAF (I think...it has a strange venturi tube around the sensor element and a lot more laminar flow grid material throughout.) Economy rapidly went up and I recovered about 5% of power too.

I hope this airbox (VR6 type) doesn't leak like my last one. I tried being uber-anal about seating the foam seal around the edges of the box using a credit card to get a smoothed seal. This is getting expensive and troublesome
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Old January 14th, 2008, 10:25   #34
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Quote:
Originally Posted by rotarykid
Last clutch in my 85 TD lasted 700,000 miles
Had one last 900,000 mies on a 79 Celica without needing to be replaced hardly ever used the starter on that car . Got almost 600,000 miles on an 82 Celica the same . Got over 500,000 on a 80 Rabbit 1.5 LS without a clutch .
Think you need to loose a few zreos there son.
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Old January 14th, 2008, 11:39   #35
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Quote:
Originally Posted by DFWDieselJet
Well, either scangauge AND VAG-COM are wrong on PD engines, or wrong on VE engines, or it's true. And that's with no accessories, not even DRLs.

Keep in mind that at .3 gallons/hour, you could idle a PD continuously for over two DAYS. At .1 gallons/hour, thats over 6 days. Intuitively, which sounds more likely?
Idle time is approximately 6 continuous days in the 1.9L TDI, regardless of VE or PD injection systems.

With the air conditioning on, that drops to about 4 - 4.5 days.
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Old January 14th, 2008, 11:56   #36
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Quote:
Originally Posted by DFWDieselJet
PD engines burn around .3 GALLONS per hour at idle once warmed up (a little less - yes LESS - until they are warmed up)... Verified on an '04 Jetta, both with ScanGauge and VAG-COM.
This sounded very odd to me, so I pulled out my HEX-USB+CAN cable and fired up Vag-Com Beta 711.1 to check on my 2006 Golf. I neglected to get logs, so I'll do that this evening.

Let's work in native units, which Vag-Com (and the ECU) work in. You verified 0.3 gallons/hour at warm idle. 1 US gallon = 3.785 liters (source) & 1 liter = 0.264 US gallons (source), so you say that at warm idle, you're burning (0.3 US gal * 1 liter/0.264 US gal) 1.136 liters per hour.

I fired up Vag-com when I went to lunch, and with all accessories off and the engine idling from a cold start, Vag-com was reporting fuel consumption of 0.6 liters/hour (53% less than your figure).
Once it was fully warmed up (after a half hour drive), Vag-com reported 0.4 liters/hour (65% less than your figure) at idle with all accessories off.

Unless you had every single accessory blazing while you took these measurements (plus a few extras) or mistook the Vag-com measurements for gallons/hour when they are actually liters/hour (which IMO is probably the crux of the issue), I don't see how this is possible unless your car has injector issues. Many other users have reported nearly the same figures (0.3 - 0.4 liters/hour at warm, accessories off idle) from Vag-com, which gets its information from the engine ECU.
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Old January 14th, 2008, 12:02   #37
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Quote:
Originally Posted by scurvy
This sounded very odd to me, so I pulled out my HEX-USB+CAN cable and fired up Vag-Com Beta 711.1 to check on my 2006 Golf. I neglected to get logs, so I'll do that this evening.

Let's work in native units, which Vag-Com (and the ECU) work in. You verified 0.3 gallons/hour at warm idle. 1 US gallon = 3.785 liters (source) & 1 liter = 0.264 US gallons (source), so you say that at warm idle, you're burning (0.3 US gal * 1 liter/0.264 US gal) 1.136 liters per hour.

I fired up Vag-com when I went to lunch, and with all accessories off and the engine idling from a cold start, Vag-com was reporting fuel consumption of 0.6 liters/hour (53% less than your figure).
Once it was fully warmed up (after a half hour drive), Vag-com reported 0.4 liters/hour (65% less than your figure) at idle with all accessories off.

Unless you had every single accessory blazing while you took these measurements (plus a few extras) or mistook the Vag-com measurements for gallons/hour when they are actually liters/hour (which IMO is probably the crux of the issue), I don't see how this is possible unless your car has injector issues. Many other users have reported nearly the same figures (0.3 - 0.4 liters/hour at warm, accessories off idle) from Vag-com, which gets its information from the engine ECU.
Nice post scurvy! Thanks for taking the time to grab your Vag-Com and see what's really going on. For what it's worth, my 2000 Beetle reported the exact same numbers that you did.

Now I'm going to sit back in my chair with my bucket o' popcorn and see what kind of responses you get.
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Old January 14th, 2008, 12:03   #38
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Thanks Scurvy, that's why I said ~.5 Quarts--quarts for the sake of us Yankeees. In any case, my numbers are coming from a 130 hp 6-speed 2001 Bora (VE) which said .4L (this was in Finland). It's also about the same as what I've seen in the past with other VE's.

Nick--your MAF is a revision C. That's all I sell these days . You're very right about the air filter though, a couple extra bucks is worth it for the cold region. Never just "check" the air filter--if you crack the box plan on replacing it. Much less expensive than replacing a MAF or a turbo.
-BB
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Old January 14th, 2008, 12:20   #39
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Quote:
Originally Posted by VeeDubTDI
What'd you do, tow it behind your RV for 500,000 miles?
Me thinks there are too many zero's
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Old January 14th, 2008, 12:22   #40
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Originally Posted by BleachedBora
Thanks Scurvy, that's why I said ~.5 Quarts--quarts for the sake of us Yankeees.
Agreed, BB. For the dimensionally challenged, when warming up my PD Golf was burning (600 milliliters/hour * 1 US gallon/3.785 liters = ) 0.159 US Gallons/hour, or 0.634 quarts/hour. At fully warm idle, it was (400 milliliters/hour & 1 US gallon/3.785 liters = ) 0.106 US gal/hour or 0.423 quarts/hour.

To put that into perspective, at warm idle, my Golf is consuming (400 ml/hr, 0.106 US gal/hour) 13.526 OUNCES of fuel per hour - a little over 1.5 cups of B11 every hour.

TDIs are very efficient.
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Old January 14th, 2008, 12:26   #41
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Hence back to my original statement about turning off the engine at lights to save 1 minutes worth of idle . What is that: .225433 oz/minute?
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Old January 14th, 2008, 12:31   #42
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Quote:
Originally Posted by BleachedBora
Hence back to my original statement about turning off the engine at lights to save 1 minutes worth of idle . What is that: .225433 oz/minute?
BB, at .225433 ounces per minute of fuel saved, that must increase your tank average to somewhere around 11tybillion miles per gallon! SIMPLY AMAZING!
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Old January 14th, 2008, 12:38   #43
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Quote:
Originally Posted by BleachedBora
Hence back to my original statement about turning off the engine at lights to save 1 minutes worth of idle . What is that: .225433 oz/minute?
Oh geez... let's see.

600 ml/hour * 1 hour/60 minutes = 10 ml/minute, which is 0.338 ounces, or right about 2 teaspoons of fuel for every minute idling.

I spill more than that when changing my fuel filter, and I'm careful.

Then again, if EVERYBODY turned off their engines while idling... just for round numbers we'll say 300,000,000 cars every day idle for an aggregate 5 minutes each (lots of cars idle WAY more than that every day), that's 1.5*10^9 minutes * 10 ml/minute = 1.5*10^10 ml or 1.5*10^7 liters is almost 4 million gallons of fuel a day.

But if I had my druthers, I would walk to work. Infinite MPG, unless we start talking about gallons of beer.

edit: swapped my b for an m, which is what i meant in the first place
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Last edited by scurvy; January 14th, 2008 at 13:57.
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Old January 14th, 2008, 12:43   #44
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Quote:
Originally Posted by scurvy
Oh geez... let's see.

600 ml/hour * 1 hour/60 minutes = 10 ml/minute, which is 0.338 ounces, or right about 2 teaspoons of fuel for every minute idling.

I spill more than that when changing my fuel filter, and I'm careful.

Then again, if EVERYBODY turned off their engines while idling... just for round numbers we'll say 300,000,000 cars every day idle for an aggregate 5 minutes each (lots of cars idle WAY more than that every day), that's 1.5*10^9 minutes * 10 ml/minute = 1.5*10^10 ml or 1.5*10^7 liters is almost 4 billion gallons of fuel a day.

But if I had my druthers, I would walk to work. Infinite MPG, unless we start talking about gallons of beer.
I think you meant to say 3 billion teaspoons per day. Also known as 3,906,250 US gallons. But hey, that's close enough to 11tybillion for me!
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Old January 14th, 2008, 13:15   #45
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Quote:
Originally Posted by rotarykid
Last clutch in my 85 TD lasted 700,000 miles ...
Had one last 900,000 mies on a 79 Celica ...
Got almost 600,000 miles on an 82 Celica the same... .
Got over 500,000 on a 80 Rabbit 1.5 LS without a clutch .
Holy Cheeses! You must've been to the Moon quite a few times my friend!
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