35MPG or less, still no answers, please help me diagnose

[Delasangre]

I have posted on multiple forums and I haven't had a single bit of help, just alot of people pointing fingers at my tuner.

I have a 2011 JSW, manual, 135k miles, and deleted and Stage 2 MRTuning. NO CEL. A year ago when I bought the car I got 47MPG at 70MPH on the freeway coming home from buying it, I also regualrly got 40 MPG average commuting to work. Then I tuned and deleted it because I was getting DPF lights and for about 1 month AFTER the tune and delete my fuel mileage was the exact same even though I expected a huge gain. Everyone and their mom goes around saying these get 55mpg tuned and deleted. I stayed getting 40 on my cummute. Then as I rolled into winter it started to drop. I got down to an average of 30MPG for months. Its now 70-80 degrees F out and the best I can muster is 35MPG. I got 38 on one trip mostly downhill but really I feel like it should have been in the high 40s.

With no CEL and my tuner double checked my tune and said it was fine I really have no idea where to start or what to look at. I get hardly any smoke if any at all. (can't see behind me while driving). What should I look at, test or datalog with VCDS?

I have done
-Timing Belt and water pump
-BOTH coolant temp sensors and thermostat
-All filters and fluids
-New Sachs SRE clutch and DMF
-Rear Calipers and parking brake cables
-4 wheel alignment
-Fully straight piped exhaust
-Fully deleted EGR

 

[Lead_Sled]

My first thought says “MAF”

 

[oilhammer]

I would think that car getting that poor of fuel economy would have an almost constant black cloud following it around, or a wet trail from a fuel leak.

Or you've got a luggage rack full of crap, or a trailer, or both.

I would get with a different tuner.

 

[Garrison]

I'm stage 3 CR170, routinely avg 45-55mpg on backroads commute (although only mid-30's on the highway @ 70mph).
Downhill is like 70mpg, or more

 

[Delasangre]

My first thought says “MAF”

That is next on the list to look at and clean. Thank you for the idea!

I would think that car getting that poor of fuel economy would have an almost constant black cloud following it around, or a wet trail from a fuel leak.

Or you've got a luggage rack full of crap, or a trailer, or both.

I would get with a different tuner.

My car is slick, no racks or hitches or towing. No obvious smoke. No puddles on the ground. I am as confused as you.

I was under the impression MRTuning is good?

I'm stage 3 CR170, routinely avg 45-55mpg on backroads commute (although only mid-30's on the highway @ 70mph).
Downhill is like 70mpg, or more

Weird, why worse on the highway?

 

[turbodieseldyke]

I would get with a different tuner.

His tuner says his tune is fine, so it must be something else.

Weird, why worse on the highway?

25mph faster. Above 45mph is when air resistance starts to take its toll. Still, mid-30s at 70 doesn't sound good.

 

[Delasangre]

His tuner says his tune is fine, so it must be something else.

To be fair he could be a hack, I honestly don't know. If someone has something bad to say about MRTuning I would like to hear it but I am not going to spend money on another tune unless someone can point to a good reason to do so not just a guess that maybe my tune sucks.

 

[oilhammer]

Second opinions are often a link to a solution to a problem. Never hurts to ask.

 

[T1MMBOJONES]

are you hand calculating it or just going off what the cluster says?

 

[Garrison]

25mph faster. Above 45mph is when air resistance starts to take its toll. Still, mid-30s at 70 doesn't sound good.

Yeah I was confused as well - I was expecting mid- 40's to 50's tbh
Stock tires, no roof rack, etc.

Any ideas? I'm happy to start playing around with tweaks/mods if I could net 50% more MPG on hwy

Seems like I'm sitting at boost RPM at hwy speeds, so not sure if that's to blame

 

[turbodieseldyke]

Seems like I'm sitting at boost RPM at hwy speeds, so not sure if that's to blame

I wouldn't think so. If that were the case, nobody would get even 40mpg at those speeds.

 

[Garrison]

Alright - so tune related is your thought? It's a malone/tunezilla stg3 w/ CP3 and upgraded 70mm intercooler; so too rich?

Small smoke cloud at WOT

 

[turbodieseldyke]

Alright - so tune related is your thought? It's a malone/tunezilla stg3 w/ CP3 and upgraded 70mm intercooler; so too rich?

Small smoke cloud at WOT

You could ask if malonezilla will let you use st2 or 1.5 or anything lower than 3 for free, and see if that makes a difference.

 

[Garrison]

You could ask if malonezilla will let you use st2 or 1.5 or anything lower than 3 for free, and see if that makes a difference.

But... muh torque

 

[Delasangre]

are you hand calculating it or just going off what the cluster says?

By hand. The dash is off about 1.5mpg

 

[Wilkins]

What boost are you running when going say 65 mph on level road, no wind. I don’t know off hand what I run at but I can check.

 

[Delasangre]

What boost are you running when going say 65 mph on level road, no wind. I don’t know off hand what I run at but I can check.

I don't have a boost gauge so I will have to log it with VCDS

 

[turbodieseldyke]

A cheap OBD plug can read boost too.

 

[Delasangre]

Looks like around 4psi at 60mph in 6th or as flat of road as I could find.