Looking to get 50MPG back

[windhys]

My 2003 TDI ALH used to get around 50+MPG while running 16" tires 205/55/16 in the beginning but gradually dropping about 6 years ago. It's been running 17" for 3 years now with 225/45/17 tires for 2 years and I upgraded it to one size up to 225/50/17 last year. I take it to my cabin in the wood often, need the extra clearance, added bug deflector and occasionally have roof rack with fairing on but it's only getting around 37-41MPG . Sometimes I can get 45-46MPG all highway. But nowhere near what it used to get. I'm hoping to get at least 45-46MPG with mixed driving while keeping my 17" setup if possible. I rarely run AC/Heater but when I need it usually only run for couple minutes to get to temp and open cabin recirculation.

This car gets regular scheduled maintenance like timing belt, air filter, fuel filter, oil change, etc. No mod done on this car, everything is stock.
Currently it's got 265,405miles and it just got new set of brake pads and rotors all around and new rear calipers.

I attached some charts from group 003, 011 and 013 to see if an expert can see something. To me it looks normal. I was looking to replace the original MAF, maybe it's dirty but I don't see anything wrong from the chart. Oh yeah, no CEL on dashboard . I’ll be replacing all the vacuum hoses with silicon one soon.

What kind of tune up would you recommend to improve my MPG while keeping 17" tires?

11 years of MPG datas

 

[STDOUBT]

Nice post!
Obviously there are multiple factors that affect fuel economy.
Many are nicely distilled into this great post:

tips for fuel economy

I've put this together in an effort to help some folks diagnose what may be a loss of fuel economy (MPGs) with their TDIs. Keep in mind, many of these items can work against your car in concert to add up to a sizeable increase in fuel consumption over time, so please don't dismiss any one item...

forums.tdiclub.com

Very much worth reading!

 

[Stupendous60]

Are your 17's the same diameter as your 16's were?

 

[windhys]

Nice post!
Obviously there are multiple factors that affect fuel economy.
Many are nicely distilled into this great post:

tips for fuel economy

I've put this together in an effort to help some folks diagnose what may be a loss of fuel economy (MPGs) with their TDIs. Keep in mind, many of these items can work against your car in concert to add up to a sizeable increase in fuel consumption over time, so please don't dismiss any one item...

forums.tdiclub.com

Very much worth reading!

 

[windhys]

Are your 17's the same diameter as your 16's were?

I added more info about my tires in first line. It is running 225/50/17 for almost a year now. It had 225/45/17, same diameter with 16" on 205/55/16 before.

 

[jettawreck]

The wider low profile 17" will cause a mpg hit and they are not any "taller" than the 16".
Bug deflector and roof rack are also minimal factors. You don't mention your speeds. Speed is wind resistance. Speed matters. A lot, despite what many claim. Unless you are drafting a truck.

 

[windhys]

The wider low profile 17" will cause a mpg hit and they are not any "taller" than the 16".
Bug deflector and roof rack are also minimal factors. You don't mention your speeds. Speed is wind resistance. Speed matters. A lot, despite what many claim. Unless you are drafting a truck.

The width is actually the same but taller sidewall for a bit extra clearance. The MPG started dropping about 6 years ago when I was still running the same 16" on 205/55/16 since beginning. I did notice a drop in MPG when switched to 17" from 225/45/17 to 225/50/17 but not much different than previous 16" setup. I keep my speed between low 60mph to 75mph on highway and coast to stop as much as possible.

 

[IndigoBlueWagon]

I'm sure you know you're working against yourself here by taking steps that are known to reduce FE while trying not to experience the consequences. Having gotten that out of the way, are your injectors original? If so they're probably worn and new nozzles and balancing might help bring some of the FE back. Then I'd look at all the little things that add up to good FE: Clean intake, no boost leaks, turbo actuator operating properly. vacuum hoses in good condition, and mechanical and electronic timing set properly (I wonder if the FE drop coincides with a TB replacement, and maybe mechanical timing isn't spot on). Usually the cause of MPG loss is a bunch of little things, not one big thing.

I bet the roof rack is the biggest MPG subtractor. I'd run through a couple tanks with it removed just to see what happens.

Also, you say you need more clearance, which is why you're running the bigger tires. You might try new dampers and springs to bring the car's ride height back to spec, unless you've already done that. Won't really impact FE unless you switch wheels and tires again, but it's a thought.

 

[Judson]

Moving from the stock 15s to my 17” longbeaches cost me 2.5 mpg. Longbeaches are about 22lbs each while the stock Avis wheels are down around 15lb each.

i currently am running 225/50s right now. I have been averaging 43mpg mixed highway and city for years. I did notice a slight fall-off as my injectors got old and out of balance.

 

[windhys]

I'm sure you know you're working against yourself here by taking steps that are known to reduce FE while trying not to experience the consequences. Having gotten that out of the way, are your injectors original? If so they're probably worn and new nozzles and balancing might help bring some of the FE back. Then I'd look at all the little things that add up to good FE: Clean intake, no boost leaks, turbo actuator operating properly. vacuum hoses in good condition, and mechanical and electronic timing set properly (I wonder if the FE drop coincides with a TB replacement, and maybe mechanical timing isn't spot on). Usually the cause of MPG loss is a bunch of little things, not one big thing.

I bet the roof rack is the biggest MPG subtractor. I'd run through a couple tanks with it removed just to see what happens.

Also, you say you need more clearance, which is why you're running the bigger tires. You might try new dampers and springs to bring the car's ride height back to spec, unless you've already done that. Won't really impact FE unless you switch wheels and tires again, but it's a thought.

I'm not expecting to get 50MPG back when I was running 16" tires but at least close to that, I'd be happy to get consistent 45-48MPG while running bigger tires. Roof racks come off whenever I don't use them. I will look into injectors, they are original for sure. I'm doing pressure test today, last time I did it found N75 valve seems to be leaking a little but after some reading, that seems to be normal. I may buy a new N75 just to compare the pressure test. All vacuum hoses will be replaced with silicon one tomorrow. I hope it will last as long as the original braided ones.

I always get TB replacement at VW dealership, hopefully they never let a rookie do the job .

 

[windhys]

Moving from the stock 15s to my 17” longbeaches cost me 2.5 mpg. Longbeaches are about 22lbs each while the stock Avis wheels are down around 15lb each.

i currently am running 225/50s right now. I have been averaging 43mpg mixed highway and city for years. I did notice a slight fall-off as my injectors got old and out of balance.

I gotta look into replacing original injectors then. You are the second person mentioned this. Hopefully the job won't be too difficult

 

[IndigoBlueWagon]

I always get TB replacement at VW dealership, hopefully they never let a rookie do the job .

That's a red flag. Look at timing in basic settings, and then in measuring blocks in VCDS. If the timing numbers aren't the same that's an indicator that the mechanical timing (everything at TDC) could be off. Dealers are known for the "mark and pray" method of timing belt replacement.

 

[Sauaciden]

That's a red flag. Look at timing in basic settings, and then in measuring blocks in VCDS. If the timing numbers aren't the same that's an indicator that the mechanical timing (everything at TDC) could be off. Dealers are known for the "mark and pray" method of timing belt replacement.

This ^^ I had experiance with incorrect timing messing up fuel mileage

 

[windhys]

This is what I found after logging in for 10mins. What does this mean?

 

[turbodieseldyke]

It means "good". You want it above the blue, almost to the green.

 

[IndigoBlueWagon]

64 is just about perfect. However, the timing can show correct on this graph and the cam, crank, and pump may still not be at TDC. That will negatively affect FE. I'd not worry about it unless the drop in FE you've experienced coincides with a belt service.

 

[windhys]

I forgot to mention, there is ticking noise from somewhere under engine cover. I only hear it during idle usually on first startup and it's not very noticeable. It's been making ticking noise for maybe 5 years now since it doesn't get louder and I don't hear it when moving. I think I should get a stethoscope to pinpoint the source, it's difficult to find it with bare ears lol.

 

[Andyinchville1]

HI,

I know you don't want to give up your rims BUT if you went to 15" light weight wheels with big on the tires (LIke 205 75R15 all seasons) when yours wear out) you should pick up extra MPG's to whatever extra "overdrive" gearing through the tires gets you (in the case above the OD effect is about 8% from factory size ... a pretty good shot in the arm as far as MPGs go (plus if you camp / adventure some extra ground clearance to boot).

I have heard that that works mainly on the highway and it helps me but I drive mostly highway ....

Andrew

PS - assuming the rest of your car is good mechanically a tune and .205 injectors also helps with mpg's

 

[windhys]

HI,

I know you don't want to give up your rims BUT if you went to 15" light weight wheels with big on the tires (LIke 205 75R15 all seasons) when yours wear out) you should pick up extra MPG's to whatever extra "overdrive" gearing through the tires gets you (in the case above the OD effect is about 8% from factory size ... a pretty good shot in the arm as far as MPGs go (plus if you camp / adventure some extra ground clearance to boot).

I have heard that that works mainly on the highway and it helps me but I drive mostly highway ....

Andrew

PS - assuming the rest of your car is good mechanically a tune and .205 injectors also helps with mpg's

I was thinking to try 15" but I don't like the look of them all and I was getting over 50MPG running 16" for years before it started dropping slowly for some reason. Now running 17" with 225/50 tires and ride height is perfect when I have to go through the wood. Not too high and not too low.

I'm gonna check injectors and replace if needed. It's the original. I don't mind getting around 45MPG consistently while keeping 17" setup.

Pic with older tires 225/45

 

[MukGyver]

Your roof rack wind deflector appears almost vertical, pushing air heavily. That with racks could be costing you 4-5 mpg. Finding a deflector you could angle 45 degrees could improve things.

But like another poster said i agree its probably a bunch of things adding up.. wind resistance is a big one though.

 

[windhys]

Your roof rack wind deflector appears almost vertical, pushing air heavily. That with racks could be costing you 4-5 mpg. Finding a deflector you could angle 45 degrees could improve things.

But like another poster said i agree its probably a bunch of things adding up.. wind resistance is a big one though.

It's actually about 45 degrees angle. The bottom of the deflector is right above the top of windshield and the top of deflector is right in front of front rack. I usually take it off when not needed, worth the hassle to gain few MPGs

 

[vandermic07]

Are you calculation the tire size difference into your ODO? That can throw off your MPG calcs.

I lost 1-2 mpg adding the hood deflector to my golf. And 1-2 mpg for the 2" lift. I used to be able to get solid 51 mpg and eek out a 53 here and there. Now im lucky to hit 50 mpgs. with these add ons. I also mostly drive 55 mph or less 95% of the time.

 

[windhys]

Are you calculation the tire size difference into your ODO? That can throw off your MPG calcs.

I lost 1-2 mpg adding the hood deflector to my golf. And 1-2 mpg for the 2" lift. I used to be able to get solid 51 mpg and eek out a 53 here and there. Now im lucky to hit 50 mpgs. with these add ons. I also mostly drive 55 mph or less 95% of the time.

Yup I adjust the tires difference in the app.
+2.8% winter tires 205/60/16
+3.5% all season 225/50/17

Up until last April I was running 225/45/17 with 0% tires adjustment and before that 205/55/16 with -0.4% adjustment since beginning.

If I was getting around 52MPG - 2MPG hood deflector - 2MPG bigger tires = I should be getting about 48MPG. My goal is to bring my FE around around 45MPG consistently while keeping current setup.

My buddy said the ticking noise is coming from the cam. It’s not very noticeable. I’ll be replacing that very soon to see if there is any improvement in FE.

 

[Judson]

Cam and lifters just getting old. I changed mine out years ago for a frank06....

 

[Another]

If you want to keep the right height and the 17" wheels you can switch to 205/55R17 tires -same with 225/50 but narrower. It's the stock size for Vw Alltrack, Mini Clubman and Nissant Kicks. The last one uses Firestone FT140 wich people complains about noise and often you cand find them on marketplace in "like-new" condition for a very good price

 

[RexNICO]

I was thinking to try 15" but I don't like the look of them all and I was getting over 50MPG running 16" for years before it started dropping slowly for some reason. Now running 17" with 225/50 tires and ride height is perfect when I have to go through the wood. Not too high and not too low.

I'm gonna check injectors and replace if needed. It's the original. I don't mind getting around 45MPG consistently while keeping 17" setup.

Pic with older tires 225/45

Those are 1 of my favorite looking OEM 17's, I think they came on NB Turbo (gassers).

Most of TDIClub will (correctly) tell you - If better FE is your goal, 15" wheels/tires is one of the best ways to accomplish that goal.

 

[windhys]

Just a quick update. I replaced all the vacuum lines with 3.5mm ID silicon hose except the turbo actuator line. I will do that the next time I get under the car and what a difference in fuel economy! I only had one size vacuum line but it fit all of them.

The last refill before new vacuum line was 37MPG, mixed driving (aggressively sometimes) and averaging between 37MPG to high 41MPG (All highway). After the new vacuum lines, the last refill was 42MPG, mixed driving (aggressively sometimes). I wanted to see how much improvement after the new hoses with same driving style before that.

So I must have a small vacuum leak enough to cause a drop in fuel economy but not big enough to cause any performance issues.

I haven't done the cam job yet but my friend told me it must be the lifter causing the hardly noticeable ticking.

I lifted the car just couple days ago with combination of wagon, vr6 coils and homemade spacer from scrap steel tube. Love the lifted ride, the oversize 225/50/17 tires fit nicely in the wheel well. I expect 1-2MPG drop with the lift. I'm taking it easy right now to see how high MPG I can get.

Before

After

 

[windhys]

Turned out to be bad thermostat. It was stuck open sometimes and got worse past couple years where it stuck open all the time. That explains the temperature hardly reaching 160 degree. It was fluctuating between 130 degree to 160 degree between highway and normal driving. It was running rich from computer burning more fuel to keep engine warm.
Replaced the thermostat and flange. So far so good. Now under the hood sounds like a quiet diesel engine . Drove over 120miles with one trip towing a trailer and fuel gauge needle sitting at a little over 7/8, only about 2.62 gallon fuel used (According to Car Scanner app connected to OBD2 port). If it stays like this then I should be able to reach over 700 miles easily. My best previously was around 800 miles, about 57MPG when running 205/55/16 at stock height.