Drop of mileage after EGR adaptation

[MilenP]

Hi guys,

Something very strange happened to my 2003 5 speed Jetta. It has around 11K miles so far. I had been driving it mostly in the city for the past 4-5 months. I had it chipped at around 3K miles. So far, with mostly city driving, I have been getting the disapointing 38-39 MPG. On long trip, I got around 43-44, but I drove fast /images/graemlins/wink.gif.
I did the EGR mod recently. Since than, the mileage had dropped to about 31-33.
The car seems to be running great, no obvious loss of power.
My fuel has been the same, for the past 1 year.
Air filter is K&N and it's OK.
Snow screen is still in palce, not clogged.
Tires are at about 33 psi.
Driving habits - no change. The only thing I might have done recently is to try to change gears at about 2200-2500, instead of at about 2000 before. No driving with AC on.
No malfunctioning devices/false codes on the VAG-COM.
Oil is Delvac 1, and I had jsut recently chaged it for second time.

So, now, since there is no sign of malfunctioning MAF on the VAG-COM - can it still be something wrong with it? I don't think it could be the turbo, since there is no loss of power.

Anybody has an input?
Thanks!
Milen

 

[mrGutWrench]

[ QUOTE ]
MilenP said: Hi guys,
Something very strange happened to my 2003 5 speed Jetta. (snip)I did the EGR mod recently. Since than, the mileage had dropped to about 31-33.

[/ QUOTE ]

__. I can't come up with a usual suspect, but my EGR mod was done with about 3K miles on odometer. I'm now at 30K and get high 50's/low 60's with a highest tank MPG of 62.4. Unless there's a lot of variation in cars, I wouldn't think that the EGR mod causes a problem.

 

[Couleetdi]

What's the EGR modification you guys are talking about. Keep asking and keep learning.

 

[03GolfTDI]

I noticed no change in mileage with the EGR adaptation.

Couleekid:

The EGR mod is just a type of preventative maintenence mod, it increses NOx emissions but lessens the chance of your intake manifold clogging with soot and oil. Basically it just turns down the EGR to emit less exhaust gas back into the intake manifold.

 

[jasonTDI]

Unless there was a mistake in the EGR setting and something else happened it should not effect the mileage.

Sorry to side track.....High 50's? Come on.......Do you drive 30 mph all the time or always down hill? There must be ZERO use of the turbo to get those numbers. I went at a steady 68-70mph for 600 miles and still only got 53.

Jason

 

[MilenP]

The EGR mode is fine. Of course, it smokes a bit more, but I could live with that. Still no fault codes on the VAG-COM.

I didn't get it, what did you mean with hight 50's?
SO far I have not had 50 mpg neither with my previous Golf, nor with the Jetta.
Unfortunately this poor gas mileage wasn't just sporadic finding. I have not refilled yet, but the fuel gauge is already on the first dash next to full and I have about 95 miles. It used to go there at about 130-140s.

My question is, since the car is still under warranty, obviously whatever's wrong, the dealer will have to fix it. The only catch is that I don't know if they might find the chip and deny any coverage. Hope this will not be the case.
Thanks,
Milen

 

[Eric Maurier]

[ QUOTE ]
MilenP said:
The EGR mode is fine. Of course, it smokes a bit more

[/ QUOTE ]
/images/graemlins/eek.gif Are you sure you didn't do it the other way around, that's increase EGR instead of decreasing it? That would account for all of your problems. Please report what number you stuffed in there, and what the MAF reading now is at idle.
You are supposed to enter the highest number possible (typically 33768) in the adaptation channel #3. Is this what you did?

 

[tadc]

Good luck getting a dealer to address any MPG issue, no matter how low. If the car is running OK and has no trouble codes they will tell you it's "in spec" and show you the door.

 

[Tin Man]

I was getting lesser fuel mileage until I found a fuel leak. It doesn't get noticed as easily as a gasser since there is less evaporation with diesel.

I get an honest 45 mpg going about 75 mph with some city driving in between.

 

[MilenP]

Dear Eric,

I am sure I did it the right way. I entered 33768 (UP from 32768). Now it reads 370 at idle as it was suppsed to read.
Thanks for the concern, though /images/graemlins/wink.gif.
Milen

 

[MilenP]

Even if there was a leak, still, the mileage dropped right around the EGR mode.
Just one more thing i did today - the snow screen removal. It was half clogged, so I hope, this could be one of the issues.
Milen

 

[Eric Maurier]

cool /images/graemlins/wink.gif
you'd be surprised how good some people are at screwing things with a VAG-Com, so I started with the obvious /images/graemlins/grin.gif
Did you check that your turbo and MAF are working correctly?

 

[MilenP]

Well, as long as the turbo goes, I can hear it when I accelerate. The car doesn't seem to have lost (obvious) power.
About the MAF - at least the VAG-COM doesn't say anything. though, from I've read it the club, this is not unusual.
What is my best way to check if it's working properly, before I bring the car to the dealer and tell them to change it, since I have just under 12K miles on it.
Thanks,
Milen

 

[Eric Maurier]

turbo: 4th or 5th gear, floor it from 2000 rpm. Read the actual boost at 3000 rpm. Should be 1900-2000mbar.
MAF: idem, real actual MAF. Should read above 800 mg/stroke. If it smokes, however, it would tend to read too high. If you have spikes over 1000 mg/stroke, you can suspect it (or whatever mod you have on your car).

 

[MilenP]

Hi Eric,
I guess, I'd have to do the test while driving the car with the VAG-COM on.
What channel should I be in while I do the test?
Thanks,
Milen

 

[Eric Maurier]

boost: group 11
MAF: group 3

 

[MilenP]

Thanks a bunch. I will try it and post the results.

 

[jajohn]

It sounds like I might have the same issue - see
my other thread on 'lower MPG with Mercedes MAF'.
I had done the EGR mod just before doing the MAF
change, and have gone from 52 MPG to 45 ever since.

 

[MilenP]

Well,
When I posted the topic initially, there were not many people replying. Now since more folks started reporting some issues with the mileage after EGR reset, I hope some of the big TDI guns /images/graemlins/cool.gif will give us their thoughts.

 

[TDIkev]

I had my car chipped and EGR adapted ( Dec ’02) and noticed a drop mileage right away. I attributed this to my heavy foot enjoying the new found power. Over the winter I expected a drop in mileage but expected it to increase in spring and summer, it didn’t. At the last GTG, I had the EGR set back to stock and noticed that my fuel mileage is back.

This confirms my suspicion that the EGR mod caused a drop in mileage. The only two things that could have contributed to a drop in mileage was the chip and EGR mod. Since the EGR reset, my mileage is back and actually better than Pre-Upsolute…......

 

[pogo]

Have a look in the "ODB scanners" forum. Under the thread "Beta Testers wanted" Eric M. is posting a new
VAG-Scope feature which can display your instantaneous MPG, as reported by your ECU.
(I think you have to be a registered VAG-COM user to use VAG Scope)

This could answer your questions very quickly. That is, drive down a strech of road at 50 mph and see what
your instantaneous gas milage is, then change the EGR setting, and drive down the same strech of road at the
same speed.

You should know right away whether the EGR setting is responsible. I'll try to do the same this evening.

(Edited - not EGR. EGR had been disabled)

 

[Rammstein]

I have a MFA cluster which gives me the fuel economy.

All I can tell you guys is that you'll have to drive for at least 200 km so the fuel economy values stabilize.

It's not a very stable thing and will start at some crazy number (like 60l/100km or 1 mpg) and then go up/down accordingly.

Just to let you know. /images/graemlins/grin.gif

 

[pogo]

When I hooked up the VAG-COM, I was surprised to
find out that my EGR valve was functioning normally.
I think the EGR was re-activated by the dealer when
they replaced the injection pump 3000 miles ago.
That's the only time the car's been to the dealer, as
I do all the service myself.

Mileage has been up 4 mpg since that trip to the dealer.
I thought it was due to the new injection pump, but it
could have been be the EGR mod.

(Edited - EGR had not been turned off, mileage increase was from new pump)

 

[jajohn]

Confirmed! I just changed the EGR back to factory
spec (32768 instead of 33768 on VAG-com). My 3 tanks
since have been 49, 50, and 49 MPG, where I had been
getting 45 with the EGR mod. Prior to the EGR mod
the car got consistently 50-52 MPG.

--
Allen
01 silver Jetta, Pierburg MAF

 

[KERMA]

My half-baked theory:

THe EGR mod recalibrates the ECU to the MAF voltage output. The net result is more fuel for a given voltage reading on the MAF. That is why there is more smoke and less economy with the 33768 adaptation. Essentially 33768 sets the fuel requirement "richer". It also reduces the EGR to almost nothing, but higher fuel use can also result.

Maybe Eric can verify my theory. I do know that my smoke is down significantly (it was already low) and the mileage is up also after I put it back to 32768 with my EGR cooler removed and EGR vacuum unplugged. Electronic gadget keeps the CEL away. /images/graemlins/grin.gif

 

[KERMA]

BTW there was more smoke initially, but after the ECU caught up its almost nothing.

 

[dieseldorf]

yeah, I have shifted our cars back to 32768 but haven't travelled far enough to draw any conclusions.

 

[AF_Jetta]

Any updates? I thought I noticed a slight drop after this mod but then again my car was brand new so I expect some break in inconsistencies. I did the EGR mod for a guy's A3 and he thinks he has seen a mileage drop. I've asked him to quantify because it doesn't make sense that mileage would drop off.

 

[Dana Bartholomew]

Just rolled my EGR back to stock. Will report back in several weeks. I thought my mileage had dipped after the EGR mod two years ago.

I figure that by using superior Cali fuel, soot damage to my intake will be minimal. We'll see...

 

[69squareback]

Same story for me.
Got my TB changed, ECU chipped, and EGR modified all at 60,000. Instantly my mileage went down and has never came back, even when I make a conscious effort to drive easy for 700 miles.
When I get a chance I'm going set the EGR back to stock, and see how it does. My intake wasn't terrible at 60,000, and I could only account for 22,000 miles of good diesel (bought it at 38K).
I'll post my results.