Checking turbo operation

I'm trying to find out why my 2003 Jetta TDI is not getting the mpg that it should be. My 1999.5 Jetta TDI gets 4-5 mpg better. I am averaging 34 mpg with about 80% city driving and 20% highway. I do have a 5-speed.

Anyways I have tried everything listed on the forums and now I am trying to check the turbo boost.

Here is the graph I made and the original data: (accelerating from about 1500 RPM in 4th gear)

RPM Requested Boost Actual Boost
1722 1040.4 979.2
1680 1050.6 1009.8
1701 1081.2 1030.2
1722 1672.8 1091.4
1722 1693.2 1275
1764 1713.6 1499.4
1806 1734 1693.2
1848 1754.4 1836
1890 1785 1958.4
1932 1795.2 2019.6
1974 1795.2 2060.4
1995 1795.2 2091
2037 1795.2 2121.6
2058 1795.2 2152.2
2100 1795.2 2162.4
2142 1795.2 2162.4
2163 1795.2 2152.2
2226 1795.2 2131.8
2247 1795.2 2091
2268 1795.2 2040
2310 1795.2 1978.8
2352 1795.2 1927.8
2394 1795.2 1876.8
2436 1795.2 1836
2478 1795.2 1805.4
2520 1795.2 1774.8
2541 1795.2 1754.4
2583 1795.2 1734
2625 1795.2 1723.8
2667 1795.2 1713.6
2688 1795.2 1723.8
2730 1642.2 1683
2751 1468.8 1550.4
2772 1438.2 1428
2793 1744.2 1397.4
2814 1795.2 1632
2856 1570.8 1795.2
2898 1795.2 1703.4
2940 1795.2 1774.8
2961 1805.4 1836
2982 1744.2 1856.4
3003 1693.2 1652.4

Column D should be requested boost and Column E is actual boost. (I think) Thanks!
(BTW I'm at 5000 ft, not sure if that matters)

What would really help is if you would log the N75% along with the boost requested/actual; will you do that for us?

mrfiat said:

I'm trying to find out why my 2003 Jetta TDI is not getting the mpg that it should be. My 1999.5 Jetta TDI gets 4-5 mpg better. I am averaging 34 mpg with about 80% city driving and 20% highway. I do have a 5-speed.

Anyways I have tried everything listed on the forums and now I am trying to check the turbo boost.

Click to expand...

You have looked through my sticky atop the Fuel Economy section and checked off each and every item that applies to your car?

And you've checked that EVERYTHING is otherwise identical between your two cars? Same tires, same brakes, same timing, all the injector spray patterns are identical (as checked on a bench), the coolant temp is the same, same lubricant in the engine and gearbox?

Wrong tires and a bad thermostat could equate to 4-5 MPG right there.

Things I have checked and replaced in trying to improve the fuel economy in my 2003 Jetta:

* Replaced intake manifold (old one was 40% coked up)
* Replaced ASV valve (old one was coked up)
* Replaced both rear calipers (old ones were dragging, new one spin freely)
* Cleaned snow screen. (40% clogged)
* Checked timing with Vagcom. Set the timing to 64 degrees at 114 fuel temp.
1/2 block below the yellow line.
* Set IQ to 4.0. (was 3.5)
* Tire pressures are at 45 psi.
* Replaced all of the smaller vacuum lines.
* Lubed turbo actuator. (and tested it and it does move when there is vacuum)
* Tested N75 valve.
* Replaced MAP sensor.
* Replaced fuel filter and air filter.
* New timing belt, rollers, etc 1 year ago. (Done by previous owner at Autobahn Motorworks in Phoenix)
(static timing has not be rechecked, but I think this is a VW knowledgable shop)
* I try to keep the car at 2000 rpm when not accelerating.
* Replaced vacuum reservoir and brake master vacuum hose with new ones.
* Tested vacuum and got 24".
* Did full EGR delete.
* Checked intercooler and no oil came pouring out of it. (removed the hose from the turbo to check it)
* Checked engine temperature multiple times. (Averaged 186 degrees F while driving in the winter)
* Cat and muffler were replaced with a straight pipe.
* Checked odometer against GPS and I am correcting the mpg figures.
* Installed Panzer plate to replace missing bottom engine cover.

(Yes, I have read the sticky) Thanks!

The rotors on the 2003 are slotted and drilled, but otherwise the brakes seem to be the same. The 2003 had 17" VW wheels on it, but I am doing a tank right now with the 15" wheels from the 1999.5 and the fuel economy doesn't seem much better)

Not sure if the oil is the same between the two cars, since I recently bought the 2003.

Not sure about the fuel injectors. Should I replace them?

The 1999.5 has 155,000 miles on it and the 2003 has 208,000 miles on it.

Looks like 86 degrees Celsius might be a little low for coolant temp, so I just ordered a new coolant sensor and
thermostat.

Both cars run great BTW and both have 5 speeds.

Here is a log that I just made:

http://irata.com/log.txt

This was a start with a warm engine in 3rd gear, so I didn't exceed the speed limit.

What about the MAF?

Go to Malone Tuning's web site and look for document on performance logging. Do the logging as they specify. You can then upload the data to their site (drag-and-drop) and it'll produce graphs. NOTE: they specify to run in 3rd gear, from about 1,500 RPM and bury your foot until redline.

On average, over the last 10 tanks, all of my cars are very close in FE. However, I regularly (and it seems like it's pretty consistent of late) see some swings between tanks: not sure why, but this winter has been really squirrelly in this regard.

What's the state/history on the injectors in both cars?

This is a graph of the boost from today starting from 1500 RPM in 3rd. Does it look ok?

Which field do you need to graph to show the operation of N75 valve? I logged groups 3 , 15, and 11. (A previous poster said they wanted the N75 valve logged, not sure if I got it)

I will do the logging Malone asks for here:

https://malonetuning.com/assets/files/vagcom_logging_guide.pdf

And email it to them for a free analysis.

I have no idea what the state of the injectors are in either car. I have the MAF logged in the logfile linked to above. The MAF has been replaced recently.

Wait, so the car has no EGR and non-stock software? And this is also the exact same as your other car?

Both cars have the EGR deleted. The 2003 has it physically removed and the 1999 has it removed through a re-flash. Both ECUs are stock otherwise.
I don't think the EGR delete affects the mileage or turbo operation anyways.
I do get the CEL regarding the missing EGR on the 2003, but I just ignore it.

That is your answer. EGR most certainly DOES effect the fuel economy when the ECU thinks it should be working and it isn't.

Put it back on, or get software that isn't looking for it to be working.

If you do not know if the 2003 injectors/nozzles have ever been serviced I would give that idea a serious consideration. The .205 nozzles will give you more power and should increase your mileage if you do not drive with a heavy foot. Years ago, I purchased .205 nozzles and had a Stage 3 tune installed as well. With 4 adults and luggage driving from West to East, at 75 MPH we consistently got 52 MPG in my Jetta. So,..... more power does not always mean less fuel economy. I currently am running a Stage 4 Custom tune with .230 nozzles and a big turbo. I am getting better FE now than I did with the factory turbo and smaller nozzles.

Can someone please explain to me why having the EGR deleted would reduce your FE? I have not seen this anywhere on this forum.

Also I was getting the same exact mileage when the EGR was installed and working.

Here is a thread where they claim an EGR delete without a tune does *not* hurt mileage: http://forums.tdiclub.com/showthread.php?p=4342230

MAF values not expected, so how can ECU properly calculate?

Longer warm up times since no heat being pulled from exhaust.

Why not just at least fix THAT part no matter what? Why?

A software change that does NOT use the EGR is going to be able to calculate differently. One of my ALHs has a MAF delete tune, with no EGR or cooler. It takes longer to warm up, but it gets excellent fuel economy, even with the 11mm pump. I did put a hotter thermostat in, not sure how much that helps, but it certainly doesn't hurt.

You seem to have an answer for everything, but are still asking questions. Very strange.

Trying to help here, and the only difference in your two cars that you have eluded to is the software and EGR. That there is enough to make a difference. Period.

I appreciate the help, but the fact is the mileage didn't change when I did the EGR delete. I will fix that part for sure, but trying not to change too many things at once.

From my research I do not think that the EGR delete hurts the mileage. (no offense)

I saw what people said about the EGR delete making the car take longer to heat up, but that is not what I am seeing. I have heat within two miles of driving in the winter. The engine seems to come up to temperature just as fast as it did before the EGR delete. It doesn't get that cold here in Albuquerque.

But so far no one has offered an opinion about my original question. It is free advice, so I can't complain. Hopefully Malone will help me with whether the turbo is working correctly, once I get time to run all the tests they want.

I have answers because I have done my research before asking the question. (which is what you are supposed to do on here)

Thanks!

Don't dwell on that EGR FE bit, if your's is the same that's fine. But meaningless.
Stick close by Oilhammer and you'll get where you want to go.

Ok, thanks. The cars are not the same otherwise I would get the same or better mileage. I did a lot of work improving the FE on the 1999.5. I recently purchased the 2003, so I haven't done everything that was done on the 99. For example the 99 had the thermostat and temp sensor replaced, the 2003 hasn't had that done, but it will be done soon.

Well those cars won't clone.
Looks like OH has the answer back at post #15.

mrfiat said:

I appreciate the help, but the fact is the mileage didn't change when I did the EGR delete. I will fix that part for sure, but trying not to change too many things at once.

From my research I do not think that the EGR delete hurts the mileage. (no offense)

I saw what people said about the EGR delete making the car take longer to heat up, but that is not what I am seeing. I have heat within two miles of driving in the winter. The engine seems to come up to temperature just as fast as it did before the EGR delete. It doesn't get that cold here in Albuquerque.

But so far no one has offered an opinion about my original question. It is free advice, so I can't complain. Hopefully Malone will help me with whether the turbo is working correctly, once I get time to run all the tests they want.

I have answers because I have done my research before asking the question. (which is what you are supposed to do on here)

Thanks!

Click to expand...

People need to keep in mind that location matters. New Mexico, while I'm sure can get chilly, is in no way similar to say Ontario.

I have my EGR components on ALL my cars and I plan to keep it that way.

One can help themselves out (did I mention this already?) by running performance logging as outlined from Malone (available doc at their site). Data can by uploaded and graphed. Data and graphing pretty much tell any story.

Yes, there are multiple schools of thought for sure regarding EGR deleting. I will do all the Malone graphing as soon as I get chance. I have uploaded two different logfiles into this thread so far, but no comments on those yet.

My car is also in a garage, so that helps it warm up faster as well in the mornings.

Those graphs only focus on boost. There's a lot more to consider (as described in Malone's instructions). But, even this data is not sufficient for accessing the turbo. Again, follow the instructions from Malone and let's then see how things are.

Here are all the requested graphs on my 2003 Jetta:

http://log.malonetuning.com/chart/2...cMCTChHBQXlzDmzzCiXcJwo/ClHZLYMObw6PCkQAAAA==

http://log.malonetuning.com/chart/2...wwo/DoGDDrCHDriZ1w4tsw43Cj1MIJ8K3PMOmJ8KPAAAA

http://log.malonetuning.com/chart/2.../QRwwJMKEcFBeXMObPMKJdwnCj8KUdktgw5vDo8KRAAAA

http://log.malonetuning.com/chart/2...3woQQDsOMwqtrWybDsW7DocKew5IPwpPCiMKUTMKTAAAA

http://log.malonetuning.com/chart/2...PRsKAw7oewo1Tw43CgcK4d8K1GMOzADUHwqBbdQAAAA==

http://log.malonetuning.com/chart/2...Pw6Bgw6whw64mdcOLbMONwo9TCCfCtzzDpifCjwAAAA==

I don't know the numbers, but I see mass air flow and boost drop under steady request.

So what does that mean?

According to the bottom graph link, your N75% is way higher than it should be also following your boost curve. Is it possible the nut on the actuator arm came loose and now the actuator arm is too short? If this was my engine I would try to make the actuator arm longer and keep testing until the boost got under control and the N75% was in the low to mid 60% range.

Ok, thanks. I will try to make the actuator arm longer and re-test. I sent the files to Malone, but I guess they don't offer free advice anymore. They told me to post the graphs on forum and ask for help.