Help me mod my sister's Jetta TDI

[Daox]

My sister will hopefully be picking up a new (to her) 03 Jetta TDI this weekend or quite soon. She got a new job a few months back and is doing a lot more driving than she used to. Her 96 Celica was doing the job, but has almost 200k miles on it, so it was time for a newer car. She wanted something that got as good or better mileage, so the TDIs were on the list. Last week we found this car and took a look at it. The owner really didn't seem to want to sell it, but needed money to fix up his house and other vehicle. He also seemed pretty anal about the upkeep of the car which is great news for us.

So, once she picks it up, I'm thinking of doing some simple mods to it. We'll start with tire pressure of course. I was also thinking grill block, but I don't know about blocking off the intercooler? Any other easy things to hit. I don't want to spend a ton of time with the car, but just something to help her out over the life of the vehicle. Any ideas are welcome!

Here are some pics and the craigslist ad.

[Daox]

Also, driving tips, (shift points, etc) would be great too.

[theunchosen]

Diesels don't operate like gassers really at all. All diesels operate at WOT and run lean. In light of that you get alot more power from every drop of fuel the more air you can get in the chamber as well.

Cold and lots of it is whats good for diesels. If you grill block to boost engine temps you shoot yourself in the foot by sacrificing much higher AFRs for a little engine temp. The pre-cooler's ability to reduce AITs is also very important. The colder the air the more you can squeeze in.

Moon disks and wheel skirts, larger tires, lighter wheels and any other potential weight reductions. If she really gets serious about it she could drop the AC completely and it has a good chance of also increasing engine efficiency because its not trapping heat in and around the air intake.

Not sure on the benefits of totally removing AC opposed to just not using it. Tuners with chargers and pre-coolers do it to get better airflow over their intake lines. . . They also do it to cool the engine better(no large shield).

[Daox]

We just got back from picking it up. Still looking for more suggestions.

She isn't a hardcore hypermiler by far. Just sensible normal driving for her (thus another reason to look at the TDI). She'll keep and use the AC I'm 100% sure.

[Jetta90GL]

I did a quick search for MPG on vwdiesel.net:

Stock Muffler & Cat Question
Upgrades to improve MPG's

I think a more free flowing exhaust could help a little. It's too bad the people on that site don't log their fuel mileage...

I also remember a thread on that site talking about adjusting the injector pump internal pressure for better mileage, but that was many beers ago.

[joey]

Hundreds of Jetta fuel logs on Fuelly. It's the second most logged car there after the Civic.

Browse All Volkswagen Jettas | Fuelly

You can sort by gas, diesel, sedan, year, etc.

[theunchosen]

Free flowing cat would be far more important than muffler. . .not at all sure what the TDI's exhaust cleanup pack looks like though. . .

[Daox]

After looking at Tas's injector nozzle thread, I think I'd at least like to run some injector cleaner through the tank. Do I just use normal fuel injector cleaner? Is it really worth it to look at different nozzles?

Also, the car is going to need a oil change in not too long. Any recommendations on oil and filter for it?

[tasdrouille]

rDon't bother changing the nozzles, but having them cleaned would be a good idea. What you need is Lubro Moly Diesel Purge, not you generic fuel injector cleaner. Also you don't run it through the tank, you run it straight at the fuel pump.

Easy Lubro Moly Diesel Purge How-To - with pics!! - TDIClub Forums

As far as grill blocks are concerned you can block the top one, all but a small square on the upper right side where the air intake is. The lower one is more tricky, no problem as soon as traffic is flowing, but when it's 80+ and you're stuck bumper to bumper the fans will kick in. BTW, you should test for proper operation of the fans. Turn the AC on and put the ventilation to 1, both rad fans should run at a slow speed. Turn ventilation to 4 and both fans should turn fast, it's a common problem for fans to go bad on the A4. Both mines are shot, so I watch the temps on my SG and conpensate with the heater core when I need it.

Check your radiator/condenser fan operation NOW - TDIClub Forums

Shift it at 2k and run her in 5th as low as 1100 rpm. If your sister does a lot of highway driving there's a taller 5th gear (actually 2 sizes) available for swap, but at around 350 + and hour of time, it takes a while to pay for itself.

At least one a week, she should mash the pedal on an onramp in 3rd all the way to 5000 rpm. This is preventive maintenance for the turbo vanes. If you drive it like a granny all the time, soot will accumulate in the turbine side of the turbo, gunking up the vanes, and you'll eventually be looking at ~5 hours of time from a TDI guru to open up the turbo and clean it.

VNT Repair Procedure - TDIClub Forums

BTW, rule #1 of owning a TDI is to NEVER TAKE THE CAR TO THE DEALER.

How much did she pay if you don't mind me asking?

[Daox]

Thanks for the tips Tas. She paid the price listed, $9000. They don't seem to get any cheaper (with that kind of mileage) here.