Adjustable FPR needed? (PMS tuning)

[Baron4406]

Ok guys I have a '92 AWD I bought a while back, its modded pretty well and I got it at a decent price. It has a Extreme level 3 16G, front mount, 3" all the way back, 255 Walbro, HKS External WG, 550 injectors, and an EFI PMS engine management system. When I got the car from the kid he admitted he was a little nervous about messing with the controls, so the settings were from the previous owner. What I noticed is that the car ran very rich, I keep leaning out the max boost fuel tables, in fact at the 2200 RPM and 4000 RPM settings at max boost I'm actually SUBTRACTING fuel. This is at 19psi of boost. My injector duty cycles never go much above 70%, I never see more than 1 or 2 counts of knock and that's only in the lower RPM's, above 4000 RPM's I have yet to see any knock. This car seems to be getting ALOT of fuel, I noticed with the 255 the kid never got an adjustable FPR. Is the reason this car seems pig rich at lower RPM's ue to a severely overrunning stock FPR?? The car seems to smooth out at 5000 rpm's and really takes off. Yea its damn fast it embarrased my buddy's 2003 Corvette, I just would like to get it to run smoother. The gas milage is awful too. since I'm sure this will be asked here's a little log info. This was from a 2nd gear pull.

RPM - knock - O2 - Inj duty% - Timing advance

2700 2 0.87 17.9 27
3000 1 0.83 28.1 23
3437 0 0.83 36.7 23
3968 0 0.85 53.9 18
4531 0 0.83 62.5 18
5093 0 0.82 67.9 20
5625 0 0.82 69.5 24
6062 0 0.80 69.5 29
6593 0 0.78 71.0 27

At the 6000 and 7800 RPM settings I'm adding like 14% and 18%. These were both in the 30's when I first started tuning this beast. The tailpipe is stained black too. If I do put on an Adj- Fpr I guess I have to go back to square one huh?? BTW I do have a fuel pressure guage, but DSM's don't have schrader valves to hook them up.

 

[King Salami]

With a 255, you definitely need an AFPR. I'm only running a 190 and I had to get one (fuel press was 41 psi w/ 550's).
You can do a fuel pressure test, but I'm sure it's too high.
I got a Full Thottle Speed AFPR that bolts on to the end of the fuel rail for $155 from www.importevolution.com
It's a nice piece.

 

[IllEagl]

those timing advance #'s are really high for WOT and adding 14%. Does the car have a hacked MAS?

 

[Baron4406]

No it doesn't have a hacked MAS, the PMS system has its own MAF. BTW I installed an Aeromotive AFPR last week and set the base fuel pressure to 38 psi. It really doesn't run any differant (kinda shocked me) however I haven't had a chance to do any logs yet. I can control the timing but I haven't touched it yet, the PMS system let you control timing advance. It just that I never seem to get much knock.

 

[FORMONTOYA]

I'll be the first to say it...test for leaks between the metering device and the O2 sensor.


Jim

 

[kelvinb]

well on the plus side your getting no knock a 255 and afpr are required. your not getting a true 1:1 ratio. and yes, this will help with fuel economy

stock fp - 240-290miles per tank
255 fp - lucky to get more the 200
255+afpr - back to where it was