2004 Golf TDI new turbo

[oil pan 4]

On a diesel you are always using the turbo.
Going down the highway you are likely making at least 2 to 3 pounds of boost and don't even know it.

[skyking]

Originally Posted by solarguy

My 04 tdi wagon (240K miles) gets the best fuel economy if I avoid using the turbo. So I accelerate gently and shift at around 2,000 rpm.

Moving to a bigger turbo will do nothing to improve your fuel economy.

Now, if you want to increase your horsepower by 40 or 50% and still break 40 mpg, a little bigger turbo makes a lot of sense.


Doubtful that you need a new intercooler unless it's leaking. You would hear it, and likely smell it.

Or in my case, 100% more HP and torque.
My wife is sometimes oblivious to the difference between our otherwise identical cars; Other times she's downright maniacal :P
That's what I was pointing out to the OP too; I gave up some MPG in the quest for power, and I went a bit too far.
Oilpan 4 is totally correct the turbo is putting out boost right off idle in these TDIs, but I get what you are saying. You stay out of it.
This is not the method for best MPG observed by many TDI drivers, they advocate brisk acceleration to get to cruising. That's what my scangauge tells me too.
She does not practice much in the way of economical driving and we get almost the same MPG week in and week out, despite all my mods and penchant for stepping right into it.
We average between 44 and 46 in both cars.

[tel]

hmm. before last summer when my girlfriend drove it to South Dakota and back (from Portland), this car regularly got 47-48 mpg. since then, it's gone down, but I figured that was due to her knocking it out of alignment on that trip and the tires being worn out.

I'll be replacing the tires with a LRR set and swapping out 15" wheels for the 17" wheels that are on there right now. I was hoping that change alone would get me up to 50 mpg, but I don't know if that's realistic.

back to the turbocharger: does horsepower always come at the expense of fuel economy? I take some pride in frequently being the slowest driver on the road, so I'm quite capable of self-control wrt the accelerator.

[skyking]

No, with these TDI you can go quite a ways. I just went too far
Ask Justin about malone and other tuning options. This is a great conversation to have BEFORE you get the turbo ordered.
When I had the stock turbo and stage 2 malone tune, it was no change in MPG and a nice boost in power.

[tel]

how about the reverse: would adding horsepower ever improve fuel economy?

[skyking]

Not really. It's all in the foot to brain linkage. A scanguage or similar is by far, and I mean totally the best you can do for the money. It can be an ap running on bluetooth. Just seeing the results of a Pulse and Glide, scooting up to cruise briskly to get the cruise MPGs going sooner, what is really a hill or not by looking at burn, these things will improve your MPG through technique. When coasting is better than DFCO, when to switch from a coast to DFCO, timing lights and how it pays off. These things are more fun and work better when you can see the results right now.

[oil pan 4]

Originally Posted by tel

how about the reverse: would adding horsepower ever improve fuel economy?

In a diesel it can.

[Phantom]

Why do you need a new turbo?
First unplug the MAF it is the clip on the intake. Now see if power is back. If so clean the MAF and if that does not fix it get a new MAF.

If there is not change replace the vacuum lines one at a time.

Next I would apply vacuum to the turbo line and check that it is functioning. It might just need the VNT turbo cleaned. For this look on TDIClub they can help trouble shoot the issue.

[skyking]

I don't think wrenching is his cup of tea. I hooked him up with a trusted TDI mechanic from the forum. He won't just toss on a turbo without checking it all out for him.

[tel]

Originally Posted by skyking

I don't think wrenching is his cup of tea.

that's about right. I don't actually mind wrenching, but this stuff feels well beyond what I'm confident working on without help. spare time is also in rather limited supply at the moment.