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Discussion Starter #1
I was wondering if you guys have any input on this---I have been running lean at hard load on my car(02 guage) and couldn't see why--since I have a crazy big fuel pump--Bosch pump from a porsche that has 250 stock HP, and a stock BB setup--t25, 370's. The only change is a front mount intercooler. I was only running 8psi, but I tried running more and it definitely couldn't take it. So today I installed my DIY adjustable fuel pressure regulator(THANK YOU CHARLIE2020 for the insight!) and upped the pressure to 58 psi and now no lean condition. I don't see why I shouldn't have been able to run 3 bar until I was over 230 or so WHP. What gives?
 

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Discussion Starter #4
I have a guage I made myself--there are 10 LED's, 1=.00V-.10V, ...10=.9-1.0V. At 8psi, it would drop to the 8'th led regularly, at 12 psi---all the way down to #1!! Tonight I'm dynoing and I'll post the results.
 

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With the stock fuel pump, my car detonated 3/4 of the way down the 1/4 mile drag strip at 6.5# boost and blew the electrodes off two of the spark plugs. Fortunately it didn't seem to cause any other damage. I installed a Walbro 250 pump, and have no detonation at 9psi now.

Lew
 

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are you using the stock O2 sensor for your air/fuel gauge? If so, then you should know that gauge is not accurate for tuning.

Maybe you're using a wideband 5 wire sensor though? This would work.
 

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Discussion Starter #7
Well, I dyno'd tonight--only got 160FT.LBS. torque though, and less HP. I have a crappy intake setup though, with a restrictive home depot elbow after the MAF...but anyway...my a/f ratio's were in the 15's...BAD.. all through the middle of the powerband. I tried hooking my fuel guage, but it was leaking, so I'll have to check that later. We tried upping fuel pressure to over 70 psi--no change!! I'm almost positive it is a fuel FLOW issue, in which case pressure has nothing to do with it. At first, it dyno'd at 140 tq., and then we bumped timing up...i'm not real sure how low it was cause I couldn't remember the timing procedure when I set it...and I set it at night and could see the marks real well...ANYWAY--got 20 torque across the board just from that. I may have more room to go too. This whole thing totally makes me want an e-manage and wideband to tune on the road and not have to set up dyno equipment.
 

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pump

i dont know much, but i think that the fuel pump may be your prob, since it isnt designed for our cars


gpriceynissan said:
Well, I dyno'd tonight--only got 160FT.LBS. torque though, and less HP. I have a crappy intake setup though, with a restrictive home depot elbow after the MAF...but anyway...my a/f ratio's were in the 15's...BAD.. all through the middle of the powerband. I tried hooking my fuel guage, but it was leaking, so I'll have to check that later. We tried upping fuel pressure to over 70 psi--no change!! I'm almost positive it is a fuel FLOW issue, in which case pressure has nothing to do with it. At first, it dyno'd at 140 tq., and then we bumped timing up...i'm not real sure how low it was cause I couldn't remember the timing procedure when I set it...and I set it at night and could see the marks real well...ANYWAY--got 20 torque across the board just from that. I may have more room to go too. This whole thing totally makes me want an e-manage and wideband to tune on the road and not have to set up dyno equipment.
 

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I second the pump. Maybe put on low boost and put stock pump back in with FPR, and see what you get.

Justin
 

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Discussion Starter #10
Well, tonight i plan to test my fuel situation...but here's something funny--I checked the timing--finally got it into timing/idle mode--and found it was at 5 degrees!! And we had bumped it up 3 and got 20hp, so who knows what it's at now. On the way home today I noticed at least another 15hp in the butt dyno. Can't wait to get more fuel in there!
 

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Discussion Starter #11
Today I checked fuel pressure under full load and it NEVER dropped off. The total pressure with my 8psi boost was 66psi. I'm even running the 4-bar and still getting lean across the board...even if I put my afc at +50% it is still the same. I'm guessing either my ecu can't drive the injectors enough, or the injectors are goofy. Guess I have to do more testing. I think this saturday I'll pick up a spare ecu for testing. Anyone got any ideas?
 

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Did you put stock fuel regulator on? I know it sounds like a waste, but after I went around spending hundreds of dollars on my fuel problem (hesitation) it turned out my grounds were just loose. A free fix that I neglected to check.

Justin
 

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Discussion Starter #13
The regulator is stock--but modified for adjustability--it's fine. I don't get any hesitation, it's just a little lean--but that's a good idea of something to check...especially since NO ONE is chiming in. Guess cause not too many people have had a lean problem with 370's and a DE ecu and an S-afc set to +50%. Things that make you go HMMMM. Tonight I'm fixing my horn so I can honk at people who like my driving enough to honk at me, and I'll go over and clean all the engine grounds...maybe even add a couple. Usually wouldn't the starter not work if the engine ground was bad? Maybe just the injector grounds are bad. Man i talk a lot..i'm outta here.
 

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gpriceynissan said:
The regulator is stock--but modified for adjustability--it's fine. I don't get any hesitation, it's just a little lean--but that's a good idea of something to check...especially since NO ONE is chiming in. Guess cause not too many people have had a lean problem with 370's and a DE ecu and an S-afc set to +50%. Things that make you go HMMMM. Tonight I'm fixing my horn so I can honk at people who like my driving enough to honk at me, and I'll go over and clean all the engine grounds...maybe even add a couple. Usually wouldn't the starter not work if the engine ground was bad? Maybe just the injector grounds are bad. Man i talk a lot..i'm outta here.
You are running more than a little lean. You are running lean for a NA car, let alone a turbo car. Are you sure the AFC is hooked up correctly? If you are making changes on the afc without any results, something isn't working properly. I'd start there.
 

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Discussion Starter #17
Yes..that something is what I'm trying to figure out. Maybe I need to measure in/out voltages of the s-afc and see if it is even adjusting the voltage at all! I checked all the afc connections(pita with all the electrical tape i used)--and they are all perfect..nice clean soldered joints. Sooooo...onward with diagnosis. On a side note, i pulled 3.5lbs of tar from the back last night. I tried heating it like someone told me...that took WAY too long. today I'll try freezing it.
 

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Discussion Starter #18
Ok, got another 4lbs. tar out...and checked the in/out of the afc--it is working perfectly, the percentages were accurate....the the ECU is getting the signal...is it controlling the injectors properly--I'm going to build my duty-cycle monitor this weekend and I'll see what the ECU is telling to the injectors. Oh yea, I DID go over the grounds--they were clean. MAF ground=good(regrounded).
 

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Are you running 370cc? I would try and get someone near you with a JWT 3bar ecu to let you use their ECU so you can see if the SAFC is your problem. I still think you should be saying goodbye to your unorthodox fuel pump though...did you check it anymore?

Justin
 

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Discussion Starter #20
The fuel pump is awesome...it will flow up to 6 or 700 horsepower...that's if I let it, by upgrading the size of the lines. That is NOT the problem....read my past posts for explanation. Yes, they're 370's. The car runs great and power is good, but should be 30 hp more for what I've got. I'm probably hitting up the salvages tomorrow for an ecu to test with.
 
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