Very Simple way to make your B6 non-returnless fuel

[O2VW1.8T]

So i talked to A4 TSCHUSS, for a bit about making the B6 into a return system. I came up with a easier way to do it.. Stuff you need

- AEB fuel rail - ebay for 1 dollar came with 4bar fpr
- MK4 1.8T fuel filter- 12 bucks at dealer
-5/16 fuel injection hose about 5 feet to be safe 3.99 a foot
- fuel line clamps - 5 bucks

What i did is installed the MK4 fuel filter in the stock location as the B6, used the stock B6 fuel line from fuel pump to filter plug and play... From the filter i ran a 5/16 hose to the evap purge line and used 2 clamps. The purge line is about twice as big as the stock feed line... So now the purge line is your new feed line.





You can see the stock feed line is now the return and the return line from the drivers side plugs right in to the feed..







So now i took out the 225 audi TT injectors and put in stock injectors with the 4 bar fpr. It runs good now, maybe its in my head but it feels better... I have uni stg2 and maybe later today i will do some logs to make sure the a/f is good if so then there is no need to upgrade the injectors on stock turbo.

[7speed]

possible next mod

[diagnosticator]

I like the idea of the return fuel system, but with your setup, the evap system is broken. The reason Audi went with the non return system is to prevent heating up the fuel in the tank from the hot fuel returned from the fuel rail. The sole purpose behind not heating the fuel in the tank, is to limit the amount of fuel vapors generated by evaporation, that must be collected and stored in the carbon canister. Now, without the EVAP system working along with the hot fuel returned to the tank, the pressurized vapors in the tank must be vented to atmosphere contributing to air pollution when the car is being driven and when parked. Over time that is a lot of fuel lost to evaporation, that would have been metered and burned in the engine during light load cruise otherwise, and making up a significant percentage of the total fuel needed at light load cruise.

I am not trying to minimize the excellent presentation you posted here, but it's important (for the forum readership,) to understand the technical implications associated with the various mods to our Audis.

[A4 TSCHUSS]

Glad I could help a little, and you definitely figured out a nice easy way to do it using the evap line!

[A4 TSCHUSS]

I like the idea of the return fuel system, but with your setup, the evap system is broken.

A lot of people take that evap crap out anyway when doing the engine bay delete stuff when taking out the sai pump and all the other excess crap in there. So who cares!

[alexza4]

I like the idea of the return fuel system, but with your setup, the evap system is broken. The reason Audi went with the non return system is to prevent heating up the fuel in the tank from the hot fuel returned from the fuel rail. The sole purpose behind not heating the fuel in the tank, is to limit the amount of fuel vapors generated by evaporation, that must be collected and stored in the carbon canister. Now, without the EVAP system working along with the hot fuel returned to the tank, the pressurized vapors in the tank must be vented to atmosphere. Over time that is a lot of fuel lost to evaporation, that would have been metered and burned in the engine during light load cruise otherwise, and making up a significant percentage of the total fuel needed at light load cruise.

on other words thank you audi once again for impairing performance of the car even more because of emissions laws...

[A4 TSCHUSS]

I say if up until a measly 8 years ago it wasn't used, then who cares! All the cars seemed to do just fine without it!

[O2VW1.8T]

Some logs im boosting 20-21psi on stock injectors with the 4 bar fpr, a little leaner then the request but it still looks good. I would care if it was in the 13.5 a/f range with the stock turbo.

http://spreadsheets.google.com/ccc?k...xOEl5OVE&hl=en

http://spreadsheets.google.com/ccc?k...zRU5LclE&hl=en

diagnosticator- My evap has been removed for over a year. I just had the purge line sitting connected to the N80 valve doing nothing... I understand the fuel heating up and stuff.

[diagnosticator]

I say if up until a measly 8 years ago it wasn't used, then who cares! All the cars seemed to do just fine without it!

C'mon man! You are missing the point entirely! I know you are smarter than that with the technical stuff. The B5 system uses the return fuel setup WITH a functional EVAP system. To claim that the EVAP and other OEM emissions equipment is useless and can be eliminated without negatively effecting important operating parameters is ignorant and cannot be supported by the facts involved. Maybe you don't care about technical accuracy, but fortunately, your opinion does not rule the forum. I suggest you be less defensive and maybe you will learn something here.

[[email protected]]

I was told the fuel maps would have to be changed in order to take advantage of this conversion.

[diagnosticator]

Some logs im boosting 20-21psi on stock injectors with the 4 bar fpr, a little leaner then the request but it still looks good. I would care if it was in the 13.5 a/f range with the stock turbo.



diagnosticator- My evap has been removed for over a year. I just had the purge line sitting connected to the N80 valve doing nothing... I understand the fuel heating up and stuff.

Yeah, good to hear that. But really, the loss of EVAP fuel vapors is a significant contributer to smog, and regardless of the pollution impact, the amount of fuel lost to evaporation if not collected and stored, is a major factor of the total cost of fuel purchased. Obviously, money wasted, that would have been used as percentage of the light load cruise fuel requirement. For most drivers, light load cruise is the main operating mode most of the time.
Finally, the EVAP Purge system has no negative effects on performance.

[A4 TSCHUSS]

C'mon man! You are missing the point entirely! I know you are smarter than that with the technical stuff. The B5 system uses the return fuel setup WITH a functional EVAP system. To claim that the EVAP and other OEM emissions equipment is useless and can be eliminated without negatively effecting important operating parameters is ignorant and cannot be supported by the facts involved.

All I can say is my car idles excellent and runs pretty good also and I also get over 20 mpg while traveling with some city driving mixed and a fair share of speed bursts with over 400whp on tap, so things can't be so bad with the evaporate not functioning correctly.

[A4 TSCHUSS]

I was told the fuel maps would have to be changed in order to take advantage of this conversion.

Been running the same Uni file since May 2009. I ran on stock fuel system for a month and then swapped to the return system.

[diagnosticator]

All I can say is my car idles excellent and runs pretty good also and I also get over 20 mpg while traveling with some city driving mixed and anda fair share of speed bursts with over 400whp on tap, so things can't be so bad.

I agree, your setup results are impressive for sure. Consider how your fuel economy could be improved, and the cost of fuel reduced with a functioning EVAP purge system, without reducing the performance at all.

[diagnosticator]

O2VW1.8T, you have PM.

[diagnosticator]

on other words thank you audi once again for impairing performance of the car even more because of emissions laws...

The EVAP purge system does not reduce performance in any way.

[A4 TSCHUSS]

Haha, touché, I will deal with my 20mpg, I am ok with that

[HTA A4]

I get an average of 28-30mpg on the highway with a little city mixed in.

[A4 TSCHUSS]

Is that actually doing the math by filling up and dividing the mileage gone on the trip computer by how many gallons or by reading your computer thing? That seems way to high unless you always drive like a grandma and do 65mph on the highway. My best ever was 400 miles on a tank with my gtrs and nothing taken out of the car. That was about 60 miles of driving around 50mph and then 60mph for 18 miles and then the rest was running 80mph on cruise control. I ran the tank extremely low and it took me 17 gallons to fill up to let you know how empty it was, so that is 23mpg.

[Abuck35]

Been running the same Uni file since May 2009. I ran on stock fuel system for a month and then swapped to the return system.

What benefits did you gain from this conversion?

Can this be done with any tune?

[diagnosticator]

So i talked to A4 TSCHUSS, for a bit about making the B6 into a return system. I came up with a easier way to do it.. Stuff you need

- AEB fuel rail - ebay for 1 dollar came with 4bar fpr
- MK4 1.8T fuel filter- 12 bucks at dealer
-5/16 fuel injection hose about 5 feet to be safe 3.99 a foot
- fuel line clamps - 5 bucks

What i did is installed the MK4 fuel filter in the stock location as the B6, used the stock B6 fuel line from fuel pump to filter plug and play... From the filter i ran a 5/16 hose to the evap purge line and used 2 clamps. The purge line is about twice as big as the stock feed line... So now the purge line is your new feed line.

You can see the stock feed line is now the return and the return line from the drivers side plugs right in to the feed..

So now i took out the 225 audi TT injectors and put in stock injectors with the 4 bar fpr. It runs good now, maybe its in my head but it feels better... I have uni stg2 and maybe later today i will do some logs to make sure the a/f is good if so then there is no need to upgrade the injectors on stock turbo.

The ability to use the stock injectors at increased fuel rail pressure is really worthwhile, and will save the cost of the TT225 injectors and add to the fueling flexibility available.. I like.

[HTA A4]

I do the math then compare it to my trip computer just to see how accurate it is. Last trip i took I got 28.7mpg (by math) and 29.9 on the trip computer. I drive 70 on the highway because I cannooott get a ticket (65 limit in IL).

[A4 TSCHUSS]

I had my car with stock fuel system running 630cc injectors on my old gtrs revo file. This was with my 2 liter, aeb head, cams, gt3076r setup. I was limited to 24psi with that setup even with an upgraded 040 fuel pump because my car would go lean, at the time there wasn't tuning available for bigger injectors. I looked around for tuning with bigger injectors and briefly tried a revo beta file after buying yet another fuel pump that was supposed to be way better and then ran some injectors that I had no clue what they were with this beta file (this was a top secret Eurocode kit). I had nothing but issues with a terrible idle and the car going to 13:1 air/fuel when I tried to run 100 octane and 30psi.

At the time, many people were questioning if the B6 fuel system was good enough to run high horsepower since the fuel pressure didnt increase with boost, and then high boost was being ran to get this big numbers also so it made a small difference in pressure between the fuel spraying out of the injectors and the pressure inside the intake manifold from the boost, nobody had made any big numbers on the stock system so I was unsure of what to do and like I said there wasn't a tune available to try something like 1000cc injectors or whatever to see if that would work either without converting. I then switched to Unitronic tuning and the rep I was working with recommended me to switch to a return fuel system. He was talking about it would better atomize the fuel by keeping the big pressure differential as well as not require me to run even bigger injectors since the fuel pressure would increase with boost allowing the injectors to flow more. That was the main reason why I did the conversion and I knew it couldn't hurt since every VW and the B5 A4s that made big power all had that type of system. I purchased the new Unitronic tune and 830cc injectors and ran the car at 25psi for about a month with the stock fuel system and everything was fine, I never tried running higher boost like the 28psi I later ran routinely. The rep then was coming to log with me and get new file revisions from what we gathered, but wanted me to convert to the "return fuel system." I bought some stuff and did the conversion and then he came shortly after. I have never tried to disconnect the vacuum source to my fuel pressure regulator so it would just run static at 4 bar like the stock B6 system and see if there was a difference or not such as maybe not being able to run as much boost before going lean. Maybe I can do that when I get my clutch and tranny back in for a little experiment.

So to answer you question directly about what benefit did I get from the conversion, I can't guarantee anything unless I do that little test, but what should happen is I will not be able to run as much boost.

[A4 TSCHUSS]

I do the math then compare it to my trip computer just to see how accurate it is. Last trip i took I got 28.7mpg (by math) and 29.9 on the trip computer. I drive 70 on the highway because I cannooott get a ticket (65 limit in IL).

I don't know how your trip computer (you are talking about going to the average miles per gallon screen?) is showing even remotely accurate. Mine wasn't even perfect with APR 1+ comparing to doing the math, and then when I got Revo software and the gtrs kit it was WAY off. Like saying I had 600 miles till empty when I filled up and saying I was getting like 45mpg while crusing using the real time mpg screen and the average mpg screen would also say like 50mpg or something crazy, and it is the same way now with Uni.

[HTA A4]

Mine has never done that. It's always within at least 5mpg. And yes the average miles per gallon screen that you can scroll thru (the accumulative setting: 2)

[A4 TSCHUSS]

Crazy stuff. Must have a voodoo car.

[HTA A4]

OP, nice coilpacks lol

[A4 TSCHUSS]

I saw that too, got the hybrid going on.

[drjonez]

Fantastic post and innovation. Slap an AFPR on there and you should really be able to tweak things to your liking.

As always, diagnosticator has covered everything...

[IVRINGS]

I was going to say when are people going to say why are you running two different coil packs. How is that good on the car in any way? With the sale of D packs of 16 bucks each I would pick up 4 next time you are out.

[O2VW1.8T]

OP, nice coilpacks lol

The good old hatchi's always seem to work. I need to buy 4 new revised ones just waiting on these to fail

I was going to say when are people going to say why are you running two different coil packs. How is that good on the car in any way? With the sale of D packs of 16 bucks each I would pick up 4 next time you are out.

I drove across the country from NC to WA state in the winter this christmas with these coilpacks lol.. No problems yet just waitng on the 2 other push downs to blow so i can buy 4 new ones and hopefully be done with this coilpack mess.

[bananas]

I don't know how your trip computer (you are talking about going to the average miles per gallon screen?) is showing even remotely accurate. Mine wasn't even perfect with APR 1+ comparing to doing the math, and then when I got Revo software and the gtrs kit it was WAY off. Like saying I had 600 miles till empty when I filled up and saying I was getting like 45mpg while crusing using the real time mpg screen and the average mpg screen would also say like 50mpg or something crazy, and it is the same way now with Uni.

My ASP software updated the trip computer values, but Uni did not. Also, maestro allows you to tweak the trip computer mpg. Mine is spot on right now

[BreakMyWallet]

link to the ebay fuel rail?

[7speed]

cheapest I found today

http://cgi.ebay.com/ebaymotors/99-00...item3ca731ecca

[diagnosticator]

I was told the fuel maps would have to be changed in order to take advantage of this conversion.

That makes sense, because the stock B6 ECU does not factor the regulated fixed value fuel pressure using a return system. Instead with the returnless system, the ECU maps adjust fuel based on a decreasing pressure gradient with increasing load and rpm, with real time fuel mass adjustment according the wide band pre cat O2 sensor signal.

[diagnosticator]

Regarding the MPG display, there is an adaptation channel in the IC to calibrate the fuel rate/mpg. IIRC, it is +/- 10 %. However, even running APR stg 1, the required calibration percentage exceeds 10%.

[AudiHere04]

So could you hypothetically use the B5 return system and EVAP in our cars, thus getting best of both worlds?

[O2VW1.8T]

Just add a new line from the fuel filter to the fuel rail and your done and didn't have to touch the evap system

[nein-reis]

So could you hypothetically use the B5 return system and EVAP in our cars, thus getting best of both worlds?

You would be better off using a B5 rail, and a 3.0 return system parts... everything would be an exact fit.
That is what I have:

[dougyfresh]

I was told the fuel maps would have to be changed in order to take advantage of this conversion.

Everything in the ECu is based off a 4bar static fuel pressure. So, to do this correctly (and robustly).... the maps within the ECu need to be adjusted.


If you're running speed density (no MAF) then you have less to modify since you've bypassed just about everything in the ECu.