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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 October 9th, 2017, 12:32   #1
tonyweiss11
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Default Better MPG vs. Engine Care Questions

I've been reading around on many of these great forums on how to increase MPG, when to shift, RPM, driving style etc. to try and get the most out of my TDI in lifespan and in MPG. After reading a lot of different threads there seems to be a fair amount of contradiction on increased MPG vs the life of the engine and turbo. So I've got a few question I want to throw out there and see what is best because I'm still a little unclear.

Current Status:

2001 Jetta TDI, ALH engine code, 5 speed. 228K miles, put 50K on since owning it and averaged 46.7 with a roof rack and bike holders for last 25K or so.

What I know:

Don't lug the the engine. Use 5th gear as much as possible. Once a week or so run through the roof on the rpms pedal to the medal in 2nd, 3rd, 4th to blow the crud and soot out. Don't waste time on cold starts, start driving immediately. Anticipating driving for light, stops, hills and downhills. Coast in gear as much as possible when <50 mph. Coast in neutral when >50. Depends on situation of course but as a rule of thumb. Don't rev engine to high when cold. Try to shift above 3K rmp most the time. Peak torque is 1900 rpm. Try and stay in range of 1900-2500rpm. Increase speed increases wind resistance by the sq. so the faster you drive the more air resistance = less MPG. Ideal speed is 55-60mph. Try to avoid using breaks as it is lost KE. Observe the 120 rule for estimated mpg vs. speed. Filters replaced at specified intervals, oil changed with T6 every 10K miles, tires at or near max psi, and other regular maintenance, timing belt. Coasting in gear uses no fuel while coasting in gear uses 0.5 Liter per 1 hour. Pulse and glide method for hypermiling. Shut engine off if you think it will be running longer than 10' as it takes roughly 10' worth of fuel to start up if warm.

What I don't know or am unclear on:

1. How to use the Right foot? Does actually using a heavy right foot help mpg vs a light one? I have read it does and doesn't. Specifically getting up to speed for hwy or cruising speed should I have a heavy foot in short accelerations up to or above 3000rpm or a lighter foot with longer accelerations?

2. When accelerating up to speed, especially in city driving where terrain is relatively flat and speed limit is +/-45mph. Should I punch through gears by accelerating fast and getting up to speed and cruise in 4th? or take a slower acceleration up to speed and flip flop between 4th and 5th when needed?

3. Does using a heavy right foot in 5th gear keeping rpm at 2000 or above have better mpg than using a lighter right foot in 4th? Example going up a hill, I can keep it in 5th by going heavy right foot and keep rpm above 2000 but I feel this may use more fuel than dropping speed a little and shifting to 4th with a lighter right foot. I'm not sure though.

4. When shifting up, does every shift need to be up to or above 3000 rpm, going from 1-5th? I feel like when I do this in the city I end up wasting energy by having to break for the next light or car in front.

5. I know I should use 5th as much as possible, but in driving small hwy or city how does this effect mpg if you use 4th at around 40-45mph to keep from lugging engine vs 5th?

6. When coasting in 5th on a flat, downhill or up to a stop is it okay to leave it in gear at 1100-1200 rpm if no lugging appears to be going on and no right foot is applied, strictly just coasting in gear at a low rpm in 5th. Is this the same for other gears as well?

7. Is it okay to accelerate from low rpms (1300) in 5th on flats or downhills if it is gradual and light right foot? I know trying to punch it from low rpms is bad on the turbo.

8. When accelerating, what rpm should be a rough target to start? Example, say you roll up to a light in 3rd and right as your getting there it turns green, rpms are 1200, should I gradually accelerate in 3rd, downshift to second, or heavily accelerate in 3rd?

I know these are semi specific scenarios but I think they are very relevant and the concept is what I am wanting to understand so I can apply them to my driving style to increase MPG but still take care of the engine/turbo so my TDI will live a long life! Many more miles to come.

Feel free to add or change or correct me on anything

-Tony
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Old October 9th, 2017, 12:40   #2
oilhammer
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You are overthinking it. That is the best part about the TDIs: you can drive them in a "spirited" fashion, and still get VERY good fuel economy.

I have a sticky in this section of the forum. Does not really have a lot about driving style, but safe to say that driving too easy for too long is not a good thing.

I try and drive in a manner that makes use of the best areas of useful RPM on that engine: 2000-3000. In other words, when cruising along I am always somewhere in that range, and tend to roll on to the power and not stab it constantly. Of course, on the rural highways I frequent, I simply run out of gears to stay below 3000, so I just find peace with the fact that I may be using a little more fuel to run at 85, but I am still using less than a gas Golf doing 70, so I still win.

The ALH engine, and its Garrett turbo, are pretty darn tough. You'd really have to try hard to do something within the confines of driving style to truly "hurt" them. If you are getting 45+ I'd say you are doing fine.

Drive more, worry less.
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Old October 9th, 2017, 15:27   #3
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I'd pretty much agree with Brian - don't overthink it. The ALH LIKES to work hard - 2000-3000 is a good range to shoot for. My Beetle is not stock, so it WILL pull redline in gears above 1st and 2nd (although it smokes like a train doing so). Drive it and maintain it properly and it will serve you well.
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Old October 9th, 2017, 20:20   #4
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The ALH motors like to be "run through the gears" on a regular basis. Yes, for for a total of less than one minute you are "minimizing" your fuel economy, your engine will thank you for it. Yes, there are a lot of owners that have built some serious power into their TDI's--mine included--and in addition to the fun factor the MPG's just can't be beat. My original Stage 3 tune with .205 nozzles got 52 MPG at 75 MPH; this is with four adults and their luggage heading from Reno to Tulsa. My Stage 3 tune provided a HUGE increase in available power, and multiplied the fun factor exponentially, but as long as I wasn't into the throttle all the time my fuel economy was stellar.
For me I usually drive by both RPM's and/or boost values; if I stay under 5 PSI when I shift my FE is 40+ in town, and/or I stay under 2200 RPM when I shift my FE stays very high. So you can tune your ALH for more power and better fuel economy all at the same time. Or, you can always "drive it like you stole it" and still embarrass the equal engine displacement gas motor cars when it comes to FE.
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Old October 10th, 2017, 13:58   #5
tonyweiss11
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Sounds good, Thanks guys. I appreciate the comments and information. I guess I need to focus more on driving than worrying!

Right now I am totally stock, would injectors or a tune be a good first mod? Not sure my clutch would last if I did either, it's still the original at 226K so it probably won't last to much longer anyways.
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Old October 10th, 2017, 20:14   #6
scooperhsd
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HA! - Mine got it's larger injectors when the fuel pump was replaced (297,000 miles), and my tune was done about 6-9 months later. The tune had a couple purposes -

1. More zip (especially at higher RPM)
2. Lower the amount of smoke between 2000 and 3000 RPM

You need to be careful on how much "zip" you add with a manual transmission without also beefing the clutch up. Since mine started as a 4 speed automatic, the 5 speed manual conversion got a Single mass Flywheel instead of the normal Dual mass flywheel - I feel like I'm getting some clutch slippage now that might need to be addressed.

BTW - I'm currently at 361,000 miles and I fully intend to make 500,000 miles - with the car in it's current state of tune.
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Last edited by scooperhsd; October 10th, 2017 at 20:25.
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Old October 10th, 2017, 20:19   #7
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The least expensive way to go first is a tune. Even with the most mild tune--Stage 1 or Stage 1.5, or Stage 2-- you will get better performance and better economy as well. Your injectors/nozzles still sound to be in great shape, but at 226k getting them refreshed would not be a bad idea. My Stage 3 tune had over 100k miles on it and my clutch that had a total of 200k miles in total was still stock and still did not slip. It is not uncommon for factory clutches to last 300k miles as long as they are not abused on a regular basis.
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Old October 11th, 2017, 07:49   #8
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If you want better mileage take the roof rack off when your not using it. That will do more than anything you can change with your right foot. I've tried driving for economy and got 54 mpg over a few tanks. Gave up on that a while ago cause I found that I can just absolutely beat the car and still average 52-53mpg. This is with a stage 1 ish tune.
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Old October 11th, 2017, 16:24   #9
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Quote:
Originally Posted by Nevada_TDI View Post
The least expensive way to go first is a tune.
Sorry, but the FIRST step is the injectors in the ALH engine. Then if you want more get a tune.
Injectors are less expensive than a tune and you may be able to get a good used set of injectors from someone parting out a ALH.

Doing it the other way around you pay twice for a tune !!!!!

I also agree with Exenos, ditch the roof racks when not in use !!!
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Old October 11th, 2017, 18:39   #10
tonyweiss11
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Yeah, I definitely take the roof rack off when not in use. I take my bike with me everyday to bike from work to school so I use it everyday at the moment. It dropped my mpg from 47-49 without the rack to 44-47 with the rack and a bike on about 3/4 of the time.

For injectors would you go with the .205 or the .216? I'm really just looking to increase economy at higher speeds say 75 mph on the hwy, also would like to get a little more power, I have a 4x8 trailer I pull around on occasion.

If I went for a tune as well, what are the benefits and disadvantages of the stage 1, 2, and 3? As recommended above would the Stage 1 or 1.5 be the way to go to start?

Also is the VR6 clutch the best option for factory replacement/slight upgrade?
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Old October 12th, 2017, 07:40   #11
Exenos
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Personally I'd go for the .216's. They can max a stock turbo while the .205's will leave you wanting. Plus shorter injection duration for same fuel as the 205's. However .216's will probably smoke without a tune while 205's shouldn't.

The vr6 is a good option if you want a single mass flywheel. I have a vr6 clutch in my car and it holds maxed stock injectors but they're supposed to be good for 300ftlbs. It does chatter something fierce at idle though. If your dmf is good and you have no plans for a larger turbo I'd just go for an upgraded dmf clutch.
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Old October 12th, 2017, 09:50   #12
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Jetta Pilot, I don't want to get into a war with you here... IF, yes IF, there are a set of used nozzles/injectors available, then yes you could be paying twice for a tune. Kerma, IIRC, does free updates to tunes if you purchase your tune and parts from them, so that (sort-of) kills the double charge concept.
I agree that .216's are likely the best all-around option if there are more upgrades in your future, but they will likely be smoky without a tune. The .205's are the European "factory" nozzles for the 110 HP ALH motor, and with a proper Stage 3 the .205's can make 140 BHP on any given day, a 50% increase in power in an ALH is a HUGE amount.
When my ALH had a Stage 3 tune and .205 nozzles, our 4 adults and their luggage got 52 MPG at 75 MPH on our way from Reno to Tulsa.
You can have your cake and eat it too with an ALH.
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Old October 12th, 2017, 18:28   #13
tonyweiss11
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Thanks Nevada TDI, Jetta Pilot, and Exenos. Sounds like the .216 is the vote for best all around combo'ed with a stage 3 tune. Right now my current plan is to do nozzles and a tune. A new clutch when this one wears out.

I do not plan to do turbo upgrade or exhaust. Just trying to get a little more HP to combo with the already great torque and increase MPG at higher cruising speeds.

Are .216 still the best choice even if I don't upgrade turbo, intake, or any other engine mods?

I have a local friend who tunes TDI's and specializes in diesels who I may have do my tune. Do most of you guys use KermaTDI for yours? That seems to be pretty highly recommended.
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Old October 13th, 2017, 05:54   #14
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205 wouldn't smoke without a tune but 216's most likely will. It depends on how you feel about smoking a bit.

For the tune Kerma, Malone, TDTuning ect are all good. Rocketchip seems to be good too but I don't hear the name tossed around too much any more. Really for a stage 1, 2 or 3 tune you cant go wrong with any of them. Just comes down to preference and who you like better. So if your local guy is comparable in price it might be worth getting your tune from him so you have local support. Plus sporting local guy.
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Old October 13th, 2017, 07:04   #15
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Quote:
Originally Posted by Exenos View Post
Rocketchip seems to be good too but I don't hear the name tossed around too much any more.
Well, Jeff (Rocketchip) does all his tunes in person and he is still in demand. There is a GTG he is attending tomorrow and there are 15 individuals already on a list for his tuning services. So he is still a valid option especially for those on the East Coast and most Midwestern locations as he is based out of Pennsylvania.

As for getting your car tuned be advised if you have a stock 5-speed it most likely will slip especially in colder weather. This partially depends on what tune you go with and if the nozzles are changed out. So you may want to budget for a new clutch down the road in case the new tune makes the current one slip. Been there, done that with the A4 Jetta I used to have.
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