cynet2k Posted July 14, 2009 Share Posted July 14, 2009 Ok I have a big problem. I have a progressive fuel pressure drop happening when i hit max boost at 3900-4000rpms 28psi boost. FP starts at 73 and at 3900-4k it starts slowly progressively drop until around 6300 when we let off because the AFR leans out. During that time the IDC slowly climbs from 75% at 4k RPMs to 94-95% at 6300-6400 AFR is 11.2-11.5 across the board ... till 6300 then it leans out ... I have no meth and no timing added yet its all stock ECU values. RR is setup to REV to 8k RPMs and will but unsafely because of lean AFRs. My Setup: UTEC+RR Fully Built Race Long Block HTA GT3076 .82A/R Rotated Kit Perrin FR 925cc TF FIC Injectors Walbro 340 FP Full Perrin Exhaust Custom 4" Big MAF Intake Link to comment Share on other sites More sharing options...
testes1010 Posted July 14, 2009 Share Posted July 14, 2009 The IDC% are maxxing out at 100% but the AFRs are going lean? If the IDC% is max at 100% fuel is not being cut. what is the load(g/rev) doing at this point? Have you increased the MAF scale Maximum value? I'm assuming still pull-thru MAF, not blowthru. Also you are not using SD on the UTEC at this point correct? Link to comment Share on other sites More sharing options...
cynet2k Posted July 15, 2009 Author Share Posted July 15, 2009 its still MAF setup I will grab the ROM from my laptop at work and let you know. also, i have a steady 73 fuel pressure until 6400rpms then once i hit that rpm it drops into the mid 60's Link to comment Share on other sites More sharing options...
cynet2k Posted July 15, 2009 Author Share Posted July 15, 2009 Max MAF Limit = 400 Max Engine Load Limit = 4.0 I also just noticed that my Initial and Max WasteGate Duty only goes to 6400 could that be the problem? my DBW requested torque tables go to 8000 but my Target Throttle Plate Position Tables go to 6800 I should probably change this to 8000 too correct? Link to comment Share on other sites More sharing options...
cynet2k Posted July 15, 2009 Author Share Posted July 15, 2009 i thought that the last value carries so i dont think any of that will make a difference Link to comment Share on other sites More sharing options...
NSFW Posted July 15, 2009 Share Posted July 15, 2009 I don't think it will make any difference. If it did make a difference, I think we'd see it in boost levels, not AFRs. It seems like a good idea to rescale those out to 8000 anyway though, in case you find a need for different WGDC at 6800 vs 7800 (which seems likely to me, but I have the redline at 7000 so I can only speculate). Link to comment Share on other sites More sharing options...
cynet2k Posted July 15, 2009 Author Share Posted July 15, 2009 yes but that will be taken care of by the UTEC once the base AFRs cooperate. I UPDATED THE EXACT ISSUE IM HAVING SEE POST #1... Link to comment Share on other sites More sharing options...
testes1010 Posted July 15, 2009 Share Posted July 15, 2009 also, i have a steady 73 fuel pressure until 6400rpms then once i hit that rpm it drops into the mid 60's Are you using the stock FPR? 73psi(base fuel pressure + 1:1 boost psi:fuel pressure increase) is about right for 28psi using the stock FPR but the drop sounds as though the fuel pump is not up to par as far as the pressure goes. You might also log to see if the Fuel Pump duty cycle changes at 6400rpm, it should still be 100%. Link to comment Share on other sites More sharing options...
cynet2k Posted July 15, 2009 Author Share Posted July 15, 2009 yes 1:1 using a stock WRX FPR its a brand new Walbro 340 255LPH which can handle 80+psi im thinking maybe either a FPR vacuum leak or bad FPR... anythoughts? Link to comment Share on other sites More sharing options...
testes1010 Posted July 15, 2009 Share Posted July 15, 2009 its a brand new Walbro 340 255LPH which can handle 80+psi It is a GSS342? I thought from the original post you were using a 340lph pump which might have been different than what most use which is the GSS342 255lph high flow/high pressure pump. Thats why I was questioning the pump. Link to comment Share on other sites More sharing options...
LGT_King Posted July 15, 2009 Share Posted July 15, 2009 Personally I would not trust a stock FPR and a walbro to run 920s and 28psi. Link to comment Share on other sites More sharing options...
cynet2k Posted July 15, 2009 Author Share Posted July 15, 2009 your right let me make sure its a GSS342 because i thought the 255lph was the 340 they might have ordered the wrong pump and i just threw it in sh*t! (i asked for the 255lph) reliablity of the stock FPR and walbro are two dif things here... Link to comment Share on other sites More sharing options...
rao Posted July 15, 2009 Share Posted July 15, 2009 You need to test the pressure of the fuel line. I think I saw this same movie a few weeks ago you can speculate and hypothesize until the end of time but until you take the fuel pressure readings you will not know what the problem is.. I would also take the UTEC out of the picture (forever) or at least until you figure out what is going on. Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
cynet2k Posted July 15, 2009 Author Share Posted July 15, 2009 wiring to the pump had a bad ground last week im just so aggravated cuz im so close to done i put a FP gauge on it and the pressure went down during the pull how much do you think it will drop overnight? Link to comment Share on other sites More sharing options...
rao Posted July 15, 2009 Share Posted July 15, 2009 I always enjoy the precision of tuning When you say that the pressure went down, what do you mean From 1 to 0, from 100 to 99 from 89 to 56.7. I am going to guess it will drop some overnight. If you keep messing with it it will drop a lot during the months when you are rebuilding your engine Good luck. Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
cynet2k Posted July 15, 2009 Author Share Posted July 15, 2009 at least i get a good laugh the second half of your coments. drop from 73 to 63 (ROUGHLY) Link to comment Share on other sites More sharing options...
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