TDI, better MPG from hard acceleration?

[ecomodded]

Is your tdi 90 hp or 110 ?

it may matter as I seen in the ad its for a 90hp Jetta , and in other ads with this or similar tuning boxes lists the Jetta as the 90hp variety.

it says 110hp for the golf but not the Jetta..

[Rango318]

I have the 90hp version.

Also, I have a story and a question for everyone.

Story first
Last Tuesday I decided it was time to change the injector nozzles. All was going well until I broke one of the injector hold downs, and that caused me to break a nipple off one injector. 1 week and $70 later, yesterday I got it all put back together correctly. Now it is running better than ever with a noticeable power boost. My torque app is reading that my load percentage is down, and it takes less throttle to do any given speed. It use to be 33% throttle was 50mph, now it is 58mph under the same engine load (~50%).

Here is the question. The fuel flow rate per hour is still the same numbers roughly. Wouldn't the larger injectors flow more fuel per hour? And if so, shouldn't that have changed my readout?

[ecomodded]

ECU Adjustments

There are two ECU adjustments relating
to fuel and air delivery that are
relevant when changing to larger
injectors:
idle injection quantity and EGR adjustment.
Both of these adjustments require a VagCom (Ross-Tech: Home) or VAG scan-tool.
You might also want
to check injection timing while youíre at it.


Idle Injection Quantity:
Larger nozzles will deliver more fuel than the ECU thinks that itís delivering.
By changing the idle injection quantity (which is sort of a misnomer),
your recalibrating some constants in the ECU relating to fuel delivery which results in better idle speed control and, depending on the state of
your particular engine, less smoke
`````````````````````````````````````````````````` ```````````````````

EGR Adjustment:
At idle and part-load situations, the EGR system recycles some of the exhaust gas into
the intake. This reduces NOx emissions. Itís possible to reduce the amount of EGR so that there is less
exhaust recirculated and more fresh
air. More air is good, because your
larger nozzles mean more fuel!
(Note: this is a good idea even for stock engines, since less EGR means less soot to gunk up the intake.
The procedures are in this tdiclub faq. pdf.

http://pics2.tdiclub.com/pdf/injector_install_howto.pdf

You will need to find someone with VagCom in your area or pay to have it done.

[Rango318]

yes, i know about the adjustments. I have a third party vagcom that I am trying to get working. Hopefully soon I will be able to change those parameters, or at least find someone who can

[ecomodded]

quote: Here is the question. The fuel flow rate per hour is still the same numbers roughly. Wouldn't the larger injectors flow more fuel per hour? And if so, shouldn't that have changed my readout?

I will be more direct

It is reading the old parameters even if the fuel is actually flowing more it "thinks" its the same as it used to be despite flowing more

[Rango318]

Got ya. That's what i wasn't understanding. Thank you for the info.

[oldtamiyaphile]

Originally Posted by Rango318

My torque app is reading that my load percentage is down, and it takes less throttle to do any given speed. It use to be 33% throttle was 50mph, now it is 58mph under the same engine load (~50%).

Here is the question. The fuel flow rate per hour is still the same numbers roughly. Wouldn't the larger injectors flow more fuel per hour? And if so, shouldn't that have changed my readout?

Generic OBD2 readers guess fuel consumption from airflow, they do not measure fuel flow at all. This is a notoriously unreliable method for many modern cars that use MAP sensors. You could double fuel flow and you'd still get the same reading.

FWIW, my SGII shows 1.5l/hr at idle for my 2.5, which is really high compared to the ~0.6 people report for their 1.9's. You can't trust OBD for fuel in TDi's it seems.