Excessive Knock, Low o2 Voltage

[95FlamingTalon]

I am starting this thread because my 95' Eagle Talon has a knock problem, which greatly worsened with the recent install of a FTS fuel pressure regulator. I just fixed the last of the boost leaks, so there aren't any that I could find. The car has a FP Big28 turbo, PTE 680 injectors, and an unrewired Walbro 190(full mod list in car profile). All my mods are no more than 2 years old and have no more than 3,000 miles on them.
The o2 voltage starts crashing around 6k. My fuel pressure is set at 44psi without vacuum. At 18psi of boost the fuel pressure rises to 62psi, then falls off to about 59psi around the same time the o2 voltage crashes. I cannot even get 10 degrees of timing unless I turn the boost down to 15psi or below. My understanding of this is that I have a fuel pressure problem of some sort. For the guys with Dsmlink, I have included a log done with only 15psi of boost and an approximate 10:1 air/fuel ratio.
I guess the questions I'm asking from all of this are:

1. Does a Walbro 190 flow enough to keep up with my setup if it isn't rewired, or would a rewire most likely solve this?

2. With a turbo as small as mine, would getting a Walbro 255 really have any benefits over the 190?

3. Should I be looking for another problem?


I will be appreciative of any information to help me solve this problem without buying parts that I don't need to have.

 

[GVR4592]

I think if you rewire the pump, you will see a significant change.

 

[95FlamingTalon]

I completed the fuel pump rewire and nothing changed at all. At 15psi of boost and an approximate 10:1 air/fuel ratio, I am still only getting 9 degrees of timing at the upper rpm's. My o2 voltage drops to .14 around 5 to 6k and my fuel pressure is still dropping off a couple psi. I am not logging injector duty cycles over 75% so my injectors aren't maxed out. This problem didn't exist untill I installed the new regulator. So, I'm wondering if I'm likely looking for a problem with my regulator or if there are normally fuel pressure problems like this associated with a aftermarket regulator install that I don't know about.

 

[nightspeed87]

then get rid of it and get a afpr and see if it changes the effect....?!~

 

[95FlamingTalon]

It is an afpr, and it shouldn't be uncommon in dsm's. The reason for this thread is to figure out the problem before swapping out unnecessary parts. Considering the pressure's dropping off at the rail, I would think it has to be in either the pump or regulator. I'm not about to swap anything until I know for sure.

 

[GVR4592]

Where do you have the vacuum/boost source for the fuel pressure regulator attached?

 

[95FlamingTalon]

It runs from the top of the regulator to the fuel pressure solenoid.

 

[Gromit]

Check out response #4 by oldman in this thread:

http://www.dsmtuners.com/forums/showthread.php?t=239480&highlight=tafflon

This will tell you how to check your regulator for a pressure leak & how to fix it if you have one. Assuming your regulator is functioning & installed correctly, if it isn't leaking then that might point you in the direction of the pump.

 

[95FlamingTalon]

That thread has great information, exactly the kind of information I was looking to find on this subject.
Now, after doing some more research, I'm slightly confused about setting the base fuel pressure. I was under the impression before to set base fuel pressure to 43 to 44psi without vacuum to the engine or regulator. Therefore when driving, I'm getting 44psi when I see 0 on the boost gauge and 62psi of fuel pressure at 18psi of boost.
I'm wondering now if that is correct or is the base fuel pressure supposed to be set with vacuum to the engine and no vacuum to the regulator(teeing off vacuum lines)?

 

[1stGenRocks]

have the car idling. unhook and pinch off the vac hose to the FPR. set the pressure to 44. reconnect the hose

 

[95FlamingTalon]

I tested the regulator and there are no leaks from the adjustment screw or from the vacuum line. When testing, however, I think I may have figured out the cause of the problem. I seems that there is a fuel leak from in between the fuel rail and the regulator. I don't know why this should be because I installed the regulator with a brand new o-ring and oiled it up sufficiently.
Another concern of mine is that the brass fitting for the fuel return line is longer than the fitting on the stock regulator, so my fuel return line is longer than it needs to be. It doesn't appear to be kinked, but it does have a significant bend in it.
To help out with answering my questions, my fuel leak is only at the higher pressures(60psi+).
My new questions are:

1. Has anyone else in the dsm community had similar experiences with an aftermarket regulator leaking from the o-ring?

2. Could a decent size bend in the fuel return line cause excess pressure to build up causing a fuel leak from the regulator, even though the o-ring was installed properly?

 

[95FlamingTalon]

I thought the leak was coming from the o-ring at the connection between the fuel rail and regulator, but I am not sure now. When I go for a wot run to the redline, the whole regulator is covered with fuel making it impossible to tell where the leak is. I tried tefflon sealing compound on all connections and pulled out the o-ring and inspected for a possible torn spot, but was unsucessful in stopping the leak.
I powered up the fuel pump and put 30psi of air pressure in the system, but for some reason the regulator won't leak then. I am not understanding why it will leak during a wot run but not during testing.WTF
What I'm asking is:

1. Is there a better test that can be done to find the fuel leak?

2. Is there a better solution to fixing the leaks than I have tried?

3. Is there anyone else with a Full Throttle Speed regulator that has had this problem?

I would appreciate some more great answers. Thanks.