Huge AFR difference between banks after 5600rpm, what gives?

[i3igpete]

if it's a leaky air port on the FPR (i think adam said that on 3st), then the fuel pressure during idle will be higher than normal as well (or your fuel trims will be lower at low cruise). Did you see anything with that?

[Toni]

if it's a leaky air port on the FPR (i think adam said that on 3st), then the fuel pressure during idle will be higher than normal as well (or your fuel trims will be lower at low cruise). Did you see anything with that?

Hmm I'll have to see if my trims have moved. I normally just glance at my afrs to see if they are still at 14.7 and haven't seen them change. I was getting 27 mpg on the way to and back from the ng so if they have moved it hasn't been off the scale.

[GTwizard]

Electricity is always in a "come here" mode. So if your wires are a tad warm, the pump is trying to pull more than what is available to it. Thats what gets wires hot. Your wires could be way too small for the pump. Everything to the pump needs to be 10 gage including the ground. I run a full fuel loop with IPS fuel rails and airomotive FPR. I only run 360 injectors and not even boosted and found the 2 banks are much more even with this set up over stock. The stock fuel system sucked when running the ram air. Rear bank was lean under ram.

[Toni]

Did some testing today...

First checked the fuel system to see if it will hold pressure to make sure the pump oring is sound. It was kinda tough because my aem afpr loses pressure immediately. Has always been like that even after swapping orifices and diaphragm. I hear this is common. I ended up clamping the return line and blipping the pump.

Seems good here. Takes a long time for the pressure to drop off.



Then I checked the regulator's operation at different psi. I used the same boost line to the regulator to my regulated compressor. Here are some boost levels:

(boost sloping is from my compressor's regulator, takes a while for it to get steady unless I put a lot of load on it)







I did the same tests before and after swapping the regulator diaphragm and there was no difference. Obviously this is not a real world test since there are no injector "leaks", battery voltage only, and the car is off. This is on a cold car as well.

Tomorrow I'm going to do some more tests and see what happens after the pump has been running for a while. I also plan to rig a voltage tester so I can log it while driving. I will figure this shit out!

[Toni]

Alright did some more things. I removed the left over stock wire (5") going to the fuel hat. I pried the terminal apart and soldered my 10awg wire directly to it. Tested with meter and there is "no" resistance measured. I also removed the ground log and grinded it down and added my own 10awg ground. Wiring should be solid now. I also added 16awg jumper wires to my logger to log voltage. I adjusted for voltage drop with my added test leads.

Here is the log. I forgot to hook up my boost sensor after testing the regulator but my gauges peaked at 14.5psi.



I extended the left scale (I usually forget) for the legend.

Voltage does not drop. However, when I logged the voltage on mmcd/palm, it drops to 12.5 from 13.6. That's weird... Is that common?

So at this point in summary:

I have solid 10awg hot wiring to the pump
new fuel pump (walbro 255)
new fuel filter
new afpr regulator
voltage at pump does not change
pump oring holds 75psi+

One thing I thought about is maybe it's something right from the start. The filter on the end of the pump. It looks a little grey. Maybe I got a tank of shitty ass gas and it is the one that is clogged? Cheap enough to replace I might as well do it anyway.

[J. Fast]

Just throwing a few ideas out there... Have you tried swapping the O2 sensors and wiring from each bank? Swap the front to rear leaving the current wiring intact and see if you still get the same reading? Maybe try reversing how you're feeding the fuel rail? Switch the feed and return lines at the rails to see if there's some kind of obstruction in the rail or the loop? It's a pain but maybe it's worth a shot.

[Toni]

Just throwing a few ideas out there... Have you tried swapping the O2 sensors and wiring from each bank? Swap the front to rear leaving the current wiring intact and see if you still get the same reading? Maybe try reversing how you're feeding the fuel rail? Switch the feed and return lines at the rails to see if there's some kind of obstruction in the rail or the loop? It's a pain but maybe it's worth a shot.

Well after I started logging fuel pressure and thinking about the fact that I've been adding a ton of fuel compared to the dyno earlier this Spring it seems that it's a global issue at this point. Initially, I only saw the discrepancy between the two banks because it was dead obvious. Now it all came together to reveal some sort of flow/fueling issue. I don't have many explanations left I feel. I'll find it

[mb3000]

This is just a wild guess, but do you still have your charcoal canister?

[Toni]

This is just a wild guess, but do you still have your charcoal canister?

Nope, that has long since been removed by the previous owner.

[mb3000]

Is the line capped or open?