Newbies and Vets: Tips for better fuel economy!

[DFWDieselJet]

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.)

 

[DFWDieselJet]

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?

 

[nicklockard]

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

 

[notachickcar]

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.

 

[VeeDubTDI]

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.

 

[scurvy]

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.

 

[VeeDubTDI]

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.

 

[BleachedBora]

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

 

[White Crow]

What'd you do, tow it behind your RV for 500,000 miles?

Me thinks there are too many zero's

 

[scurvy]

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.

 

[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?

 

[VeeDubTDI]

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!

 

[scurvy]

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

 

[VeeDubTDI]

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!

 

[dee_zell]

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!

 

[WriConsult]

0.3gph can't be right -- that's more than a lot of gasoline engines burn at idle. Much discussion of this at cleanmpg.com. Scurvy's figure of 0.16gph sounds more likely.

If you don't want to bother turning off and restarting your engine, fine. I can understand not wanting to go to the trouble for an extra couple mpg, but that's no reason to demean those who do. At a minimum, please spare us the rationalization of this as a safety issue. In half a million miles and 25 years of driving, I have seen exactly ONE situation where accelerating quickly from a stop actually prevented an accident, and that was a situation where the target vehicle was parked and wouldn't ordinarily have been running anyway.

BleachedBora's inference of about a quarter ounce a minute is about right. Doesn't sound like much, but those quarter ounces add up -- if you drive in congested areas a lot, you spend a LOT of minutes idling at lights over the course of a tank. An extreme but very real example for me: at rush hour, a 3-4 mile trip across Beaverton can easily take me 20 minutes, including 7-8 minutes idling at stoplights. In my Subaru I'll get 25-28mpg (seasonally varying) on this trip IF I kill the engine at lights, meaning I'll burn somewhere around 0.12 gallons to make the trip. If I leave my engine idling (0.25 gph) at the lights, that's another 0.03 gallons burned, increasing my fuel consumption by 25% for that trip.

Now granted, a diesel idles more efficiently than a gas engine. But remember that a TDI burns about half the fuel of my Subaru across the board, so proportionate savings is similar.

If you don't spend a lot of time sitting at lights, then you don't need to worry about this. And at shorter lights it's probably not worth the trouble for most people. But if you frequently find yourself stopped at long lights, killing your engine when you aren't using it is very much worth considering. The savings are substantial.

 

[Bob_Fout]

No one has addressed starter wear....I bet they LOVE be utilized at 10x the normal rate! Maybe they enjoy being energized 11ty billion times a day?

 

[rotarykid]

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!

I stand by these numbers . Try going form NC to Seatle & back and NC to Denver & back regularly over the last 25+ years . Or the 200 miles a day drives when I was younger . Also I wasn't always the only one driving these cars . All those miles do add up .

 

[validius]

I stand by these numbers . Try going form NC to Seatle & back and NC to Denver & back regularly over the last 25+ years . Or the 200 miles a day drives when I was younger . Also I was always the only one driving these cars . All those miles do add up .

You would imply that you lose economy charging pm the battery to replace the lost energy from cranking with the starter? Thats worse then saying that DRLs hurt economy.

My ass......

 

[rotarykid]

You would imply that you loose economy charging pm the battery to replace the lost energy from cranking with the starter? Thats worse then saying that DRLs hurt economy.

My ass......

How many amps do you think you use to run the starter & glow plugs when the engine is cold ?? I'm betting if you make that statement you haven't driven auto diesels for very long . Glow plugs heating up are like having a dead short on the battery and much strain is put on the engine burning fuel replacing those used amps .

Have you ever heard an alternator belt squeal after a cold start ?? , I'm betting you have just as I have . Just Take a drive in an old 1.6 L A2 diesel when cold after a cold start and then tell me there is no extra strain on the engine after a cold start .

DTRL running lights also pull juice but @ 80 % of full light load .

 

[darkscout]

You would imply that you loose economy charging pm the battery to replace the lost energy from cranking with the starter?

What we have here is a failure to read my signature.

 

[validius]

What we have here is a failure to read my signature.

And what you have is a failure to remove your head from your ass

 

[validius]

How many amps do you think you use to run the starter & glow plugs when the engine is cold ?? I'm betting if you make that statement you haven't driven auto diesels for very long . Glow plugs heating up are like having a dead short on the battery and much strain is put on the engine burning fuel replacing those used amps .

Have you ever heard an alternator belt squeal after a cold start ?? , I'm betting you have just as I have . Just Take a drive in an old 1.6 L A2 diesel when cold after a cold start and then tell me there is no extra strain on the engine after a cold start .

DTRL running lights also pull juice but @ 80 % of full light load .

Lets just assume your right. Its a large assumption but il leave it to VeeDubTDI and darkscout to argue if they so desire.

You honestly expect me to believe that the MINOR increase in econoemy is worth the rough duty cycle being put on the driveline by pop starting all the time? The halfshafts being banged around like that and the clutch being improperly used.

 

[darkscout]

And what you have is a failure to remove your head from your ass

Dude, don't loose your mind. I was just making a joke up they're. If you come off you're rocker that quickly I wonder what you have up their in your noggin. Sounds like a screw lose or something. I mean I didn't try to effect you in anyway, but now look how you've gone and disrupted the affect the original poster had. Here me out, there are a lot of people that are knew hear. You should calm down than come back.

 

[lildevildee]

Dude, don't loose your mind. I was just making a joke up they're. If you come off your rocker that quickly I wonder what you have up their in your noggin. Sounds like a screw lose or something. I mean I didn't try to effect you in anyway, but now look how you've gone and disrupted the affect the original poster had. Here me out, there are a lot of people that are knew hear. You should calm down than come back.

My eyes, my eyes!!!

 

[BleachedBora]

Keep it clean guys--we're trying to help everyone here .
As always, YMMV.
-BB

 

[DFWDieselJet]

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.

Thanks for the info. This is a bit of a mystery becaue my vag-com (version 409.1) shows .8-1.0 liters per hour in group 15, zone 3. That exactly agrees with SC (they are possibly both reading the same value). My SC reports very accurate fuel usage now that it's calibrated (my correction is -30%) but certainly could be accurate while driving and way way off at idle.

Obvioulsy I didn't have every (any, actually) accessory running - not even DRLs.

I'm starting to wonder if I don't have something wrong somewhere. But something wrong that only affects idle? My driving MPGs are in the mid 40s...about right for an auto PD. Any thoughs?

Gene

 

[DFWDieselJet]

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.

...

Scurvy? You have an auto or manual? Could this account for the large difference? I know shifting from "D" to "N" while stationary reduces the fueld consumption by about 30% (the .3 gal/hour I see is in "N", in "D" it hovers closer to .4). It might...that torque converter's still spinning in "N" right?

Anyone with an Auto PD and SC or VAG have any numbers to chime in with?

 

[scurvy]

MANual, of course. Any PD or VE engine idling in neutral and fully warm should give 0.3 - 0.4 liters per hour.

This is a bit of a mystery becaue my vag-com (version 409.1)

I can't help but think this might be an issue. Are you using a cheapo ebay cable? How about getting somebody else to hook up a recent version of Vag-com to your car and seeing what it says.

I logged data, but won't get the chance to tidy it up until tomorrow.

 

[WriConsult]

No one has addressed starter wear....I bet they LOVE be utilized at 10x the normal rate! Maybe they enjoy being energized 11ty billion times a day?

No one has addressed it here, but it certainly has been addressed elsewhere. Starter failure is mostly caused by a combination of age and the heat generated by long crank cycles. The short crank cycles of starting up an already warm engine don't make as much difference as you might think.

http://www.cleanmpg.com/forums/showthread.php?t=6650