Fuelling queries

[Andy_Mac]

So does someone want to school me on choosing a fuel pressure reg and its plumbing. It's one area I can't find a heap of info on, or point me in the direction of some good info.

 

Quite like the look of this dead-end setup as it means there's quite a bit less plumbing to deal with. Is there any real reason not to run it this way other than the talk of fuel sitting in the rails too long at low load and getting hot which sounds more like a bit of myth than anything else. Sure it'll get potentially warmer but by how much will be hard to prove and quantify.

 

http://i1149.photobucket.com/albums/o594/andy_mac1/9200A3CC-7A3D-4ED7-9903-3A2DFD6D5BC6_zpsvwe6adry.png

 

The rest of the fueling puzzle will be:

 

AEM 320lph pump

Radium top feed conversion rails

Fuel pulse dampers attached to rails (maybe)

ID1050x 14mm lower o-ring and either length depending on spacer used with rail

 

 

 

The other perculiar situation is i've installed the AEM pump over the weekend and now the fuel trims are majorly on the piss. Everything i'd come across online claimed you'll virtually never have any issues dropping a new pump straight in.

The trim percentages drop off as the MAF ranges rise which makes me almost think the stock reg isn't able to return enough fuel at the lower ranges causing higher pressures until the injectors are using enough to keep on top of it.

Pure speculation right there though, no idea if thats actually something that can happen or not.

Or the old pump was just stuffed and the MAF scalings were set incorrectly at the time of the tune because of this.

[utc_pyro]

Dead head fueling can cause issues with fuel vapor trapped in the rails. I've seen/heard the fuel boiling in my stock rails after shutting down, so it'll likly cause fun starting issues. It also leads to higher fuel temperature in the rails as they arent being cooled by the bypassed fuel, so the stock fuel temperature compensations will be off.

 

On the AEM pump, it can be an issue if you out flow your venturi pump in the fuel bucket. The return fuel is used to force fuel into the bottom of the bucket (there is a jet pointed at the check valve), and transfer fuel from the left side of the tank through the venturi pump. Both of these are fairly small holes and can lead to high backpressure if they are clogged or flow is too high. There is a bypass on the return inside the bucket that's supposet to prevent this but you can outflow that as well.

 

That said, the only people I've seen that reported this problem were running truly massive pumps for big E85 setups.

 

Did you mess with your FPDC tables or pump wiring? On mine it outflows the stuff in the bucket right after startup (55psi injector delta when pump is at 100%), but comes back down to 43psi injector delta after it switches to low duty cycle.

[Th3Franz]

Do not dead end the fueling. It's a bad idea on these cars.

Bump up the fpdc tables. 50% should be the minimum

[Andy_Mac]

General concensus seems to be to not do dead-head fuelling and just stick to a typical parallel setup so I'll just go with that.

Na haven't messed with the wiring or any tables, should I have made some changes to the FPDC? Never actually log it so i'll have to do some logs tonight to see what it's currently doing. Isn't 33.3% the standard lowest duty?

[Th3Franz]

Yes 33.3% is the standard but in my experience the pumps like at least 6V, hence the 50%. Using this approach I don't observe any inconsistencies in the scaling for the fuel trims.

[Andy_Mac]

Did some driving with it logging the FPR DC and it seems to be setup for 60% zero throttle/idle, 80% for any mild throttle and 100% when giving it the beans.

So may have been altered by one of the tuners at some point I guess. May explain whats going on with the new higher flowing pump. I'll get that changed and if that doesn't sort it then i'll have to chuck in a new FPR sooner rather than later

[Andy_Mac]

So don't seem to be able to change the duty cyle table at all in ECUFlash. There isn't a properly defined table from he looks of it, just a line labelled 'FUEL PUMP DUTY Experimental' way down at the bottom of the table list which doesn't have a clickable box to bring up a table for it.

[fahr_side]

So don't seem to be able to change the duty cyle table at all in ECUFlash. There isn't a properly defined table from he looks of it, just a line labelled 'FUEL PUMP DUTY Experimental' way down at the bottom of the table list which doesn't have a clickable box to bring up a table for it.

 

 

 

utc_pyro very helpfully posted that to hit the minimum voltage required on most pumps requires at least 45% duty cycle. 50% is I think a good number for idle. 60% sounds high. Note how your fuel correction value goes deeply negative on hot start up?

 

The FPDC table is defined for most ROMs. You might need to grab one of the alpha definitions from github though. Your current definition might be a bit outdated.

 

I also recommend a return system for the reasons stated above. Dead-heading is a cheapskate OEM solution from beancounters.

[Andy_Mac]

Realised that fuel pump duty cycle table works in Romraider editor so just altered it in there. Worked fine. Set it at 50% for low and 75% for medium. Fuel trims still seem to be a bit off, not quite as bad but we'll see if that's where it's gonna settle or go back to where it was before after more driving.

 

http://i1149.photobucket.com/albums/o594/andy_mac1/B635B572-E290-4EA8-BC1B-3DDC7D403510_zpsj5jq8dxj.png

[fahr_side]

Drop to 45% and see

[Andy_Mac]

Gave it a go at 45% / 65%

 

Done a fair bit of driving at those percentages so think that's where it'll stay.

Picked up an aftermarket reg today anyway so might still put that in and see how it goes.

 

http://i1149.photobucket.com/albums/o594/andy_mac1/40751034-1D4C-45E3-8A8A-1D8E75A7E2D4_zps5sduuhun.png

[Nightmaresmk]

When i upgraded i am running series just like oem. Since i am not running 500+ i didn't see the need to worry about parallel

[Andy_Mac]

Even with aftermarket rails? Not really against series, just figure since it'll all be replumbed anyway for the different rails I might as well go parallel.

 

Also put the new fuel reg in last night. Set to ~43psi at idle so we'll see how it goes today. Can't imagine it could be any worse than the OEM one with the new pump.

[utc_pyro]

Also put the new fuel reg in last night. Set to ~43psi at idle so we'll see how it goes today. Can't imagine it could be any worse than the OEM one with the new pump.

 

Is it at 43psi right at startup as well? I changed out my fuel pressure regulator in the quest to fix some random leans spots, and it's pressure is still 50+PSI right at startup due tot he pump running 100%

[Nightmaresmk]

Yes i am on IAG's rails and converted to top feed.