I rented a dyno for the day today to tune my car. Its an S4 TII with the following mods. That could be related to the issue

Vmount IC
precision PT 6262sp billet wheel turbo
custom UIM with 80mm TB
1000cc primary / 1000cc secondary injectors
-8an fuel rails w/ -6an ss lines from the factory hard line.
Aeromotive FPR
Walbro 255hp pump. In tank.
Haltech Platinum Sport 1000
Stock Port S4 motor
Full exhaust, 44mm external gate.
Running 20psi

Fuel settings in the haltech are:
-sequential firing
-staging mode: Primary Hold
-staging load :2.0psi
-DisEnrichment 0.0ms

- start tuning the haltech. light throttle and cruising are taken care of.
-move onto load pulls.
-3k to 6k are tuned dead on to 11.8:1 afr across the board
-went for some higher rpm pulls
-6400rpm is leaning out to 12.2 and by 7700rpm, its at 13.8.... not safe or good.

No matter how much I richen the base fuel map, it stays at 13.6-13.8 in the higher revs.
i went from 14ms all they way to max at 32 just to see what happens... no difference.

-Do another pull and watch the fuel pressure. base pressure at idle is set to 43psi. At roughly 5800 rpm when its making the full 20psi of boost the fuel pressure is about 60psi. it then fades off to 43psi by 6700rpm with my Aeromotive FPR where it will stay.

Heres is my headfuck... are my fuel settings possibly off? or am I running out of fuel? Isn't one walbro 255hp sufficient for my setup?

I removed the fuel filter and ran it straight from the end of the hard line to the rail to make sure that the filter wasnt a restriction, but had the same end results.

Do I need to run larger fuel lines (I have stock hard lines from the 255 pump to the -6an line where the hard line ends.... or is my 255hp pump just not enough for the 4 1000cc injectors?

Any input is apreciated... It really pissed me off to waste $ for a whole day of dyno time and no final results.... it did still make 402 hp though

Thanks guys.

 

Sounds frustrating...I don't think the lines would be a problem, some people have run them over 500whp.

Did you check your wideband against the dyno's wideband, or just use your own?

No exhaust leaks near the wideband sensor?

 

no leaks. my wideband said 13.7, dyno said 13.5.

Im wondering if I have a bad fuel pump, or just not enough flow.

the FPR holds -20inches of vacuum and 20psi of pressure without fading.

 

its the pump 100% Get a second pump, or a boost a pump, or a bosch pump... Walbro pumps fall on their face at high pressure, and you have proof good pressure and IMO lean but solid AFR's but as the rpms climb you loose pressure and lean out while running 100% duty cycle.

 

Agreed. If the pressure is falling off it's most likely the pump isn't keeping up. 11.8 is way too lean for 20 psi as well.

 

Yeah I've decided to get another pump. 11.8 too lean? What would you suggest. I'm only running about 6 degrees of timing at 20psi.

 

Also... I don't plan on making much more power than 400 anyway and would like to keep things simple and in the tank....

I see a bunch of people running the 044 Pumps... any thoughts on a Denso SupraTT pump?

thats what i've narrowed it down to.

 

AFR's will matter even with the 6* advance. The intake charge is getting compressed and heating up quite a bit before it fires, perfect chance for preignition. Something al little richer will resist the preignition by a fair bit. For 20psi 11.8 is asking for troubles. I would use 10.5AFR at 20psi as a starting point, by no means am I claiming this is "safe" or the "right" AFR but its a much more reasonable starting point than 11.8

Simplest fuel pump solution for you would be 2 walbros intank joined with a Y block. Or a single bosch 044 would likely flow enough. Personally I think for price and flow the bosch is better than the denso.

 

thanks for the input.

 

Sounds like you got a a lot going on. If you're only looking for 400 at the wheels you should be able to get that in the 14-17 psi range on that turbo with stock ports. Shouldn't need to hit 20.

Next, there is no point in increasing pulse width past 10 ms above 6000 rpm. A pulse width of 10 ms at 6000 rpm is already 100% duty. Trying to run more than that above 6000 is only asking for more fuel that's never going to come. Obviously, you need more fuel from somewhere other than the map.

Pressure is falling so it's most likely the pump. Could be the fuel filter, lines, regulator, etc. The Walbro will provide fuel for 400 whp no problem. It's not my favorite pump but it works when they're in good shape. The stock lines will do 400 whp so that shouldn't be a problem but if you have a rubber line coming apart and it's clogged your filter you'll need to address that.

In short, could be lots of things.

 

Agreed. You've got a back-end pressure problem, OP.

B

 

Have you tried common instead of Primary hold staging mode?

 

I did not. I have a Pump on order, so if it doesnt take care of my issue, I'll be trying all other avenues.