boostracingfd

need help becuase springs just around the corner and got to get her good enough to get tunned!

basically the car starts and idles fine but at about 2k , as soon as i rev it it just wants to die. if i let of it idles but if i continue to rev it it cuts out.
I have 550cc pri and 1600 cc sec w/ resistors and with all the fuel mods to support it. i have my fuel pres set at 30psi and when it starts it jumps to 40 and i cant turn it down or up.( even with the vacuum line off).

Also the motor was just rebuilt with a street port ( JR rotary) and i have gt35r turbo. i did all the blockoffs and havthe apexi power fc but no datalogit yet.

cant figure out whats causing this have searched and found no good answer. I have also tried the stock ecu and it does the same.

Any hel[p would be great!

maxcooper

You have (at least) two separate issues:
1. Can't adjust the fuel pressure.
2. Can't rev above 2K RPM.

1. Explain how your fuel system is plumbed. If you have an aftermarket adjustable regulator and no other regulator in the system (I assume the stock FPR is gone since you have an aftermarket secondary rail), you should be able to adjust the pressure. Perhaps the system is plumbed wrong or you have a bad regulator and/or fuel pressure gauge. Cover the fuel routing (line from pump feeds primary rail, then on to secondary rail, then to regulator side port, then FPR bottom port to return line, etc.). Verify the routing on your car -- it might be that the supply and return lines are mixed up, regulator ports are mixed up, etc. It is easy to make mistakes. This wouldn't have any effect on setting the base pressure with the manifold reference line disconnected, but it might affect the fuel pressure while driving -- where is the manifold reference signal coming from? You need to set the base pressure with the fuel pump running (start the engine or use the diagnostic connector jumper) -- it sounds like you set the base pressure with the engine off.

2. This might be related to the first issue, so fix that first. Did you setup the PowerFC to tell it about the larger secondaries? In a basic sense, you should only have to set the size of the secondary injectors and it will automatically adjust your fuel delivery. But the lag settings most likely need adjustment as well. Also, you often have do some adjustment to the maps to keep the same AFRs if you are starting from tuned map (though you already said that you plan to retune -- that's good). "1600" injectors are really 160 lbs/hr, which is about 1684 cc/min. The Commander only allows you to set the sizes up to 1500 cc/min -- are you using a Commander or the Datalogit/FC-Edit? What resistors did you use, and how did you wire them up?

Your system should work, so when there are problems it is usually some installation detail that is to blame. Explaining your installation in detail (and verifying that it is truly plumbed how you think it is) will help identify the problem if that is the case. I know it's no fun explaining how you did all this stuff, but the chances are that it will lead you to an answer faster than us speculating about what it might be.

-Max

boostracingfd

ok, thanks for a response. well i did set the power fc to 1500cc becuse i only have a commander no datalogit yet. the fuel lines are all ran correctly( checked and double checked) but however i did originally have aftermarket primary rail with 1000cc injector and i removed that and replaced with the stock rail and 550cc after being told that would be a problem. i still have the secondary kd rail with 1600's and resisors wired to the power wire( black/yellow). but when i reinstalled the stock primary rail i did not remove the black vacuum regulator (i think thats what it is) could that possibly be the problem, becuase i couldnt really remove it and still attach the fuel lines. also i do not have an o2 sensor hooked up but turned it off on the power fc.

well anymore ideas guys?

thanks-

rotoboy661

i have thesame problem right now mang

just use stock map for now but set the pfc to 1600's and go to the pim setting on the commander, under normal setting turn every setting from 3k 25% i did 125% from 3K all the way to redline. yes its a lil rich but u can always lean it out if u got a wideband, just a lil securiity and peace of mind (dont WOT)

AND get it to a tuner asap

thats a huge transition from 550->1600 thats why its sputtering

theres a ration but i forget its like 850->1300cc something like that but i heard some many ppl blow their engines with 1200 or 1300's so i opted for the 1600's to be safe

id rather waste gas then replace a motor

maxcooper

For your current problems, I doubt the 1500/1684 setting discrepancy is the cause. The secondary injectors usually don't phase in until about 4000RPM off boost, or lower on boost, but I would be surprised if they were coming on at 2000RPMs. However, you can adjust the transition point, so it is possible that they are coming on an dumping fuel. It would be ideal to get a Datalogit to set the size correctly, but you can also just make sure the pri/sec ratio is correct (since that's what matters for controlling the transition) by scaling the size of your primary settings down accordingly (set to 550 * 1500/1684) -- if you do this you may need to make a whole new fuel map, though. It's better just to get a Datalogit and set the real size of the secondaries.

Also, the regulator-looking thing on the primary rail is the fuel pulsation dampener and should not cause any problems with controlling the pressure (though it's a good idea to use a new one, as they are known to leak when they get old).

I want you to describe how the fuel system is plumbed because it seems like there is a probem there. It should be feed line from pump --> primary rail (firewall side, the dampener) --> front side of pri rail to front side of secondary rail --> firewall side of secondary rail to FPR side port (assuming you have an Aeromotive, SX, or one of the other common adjustable FPRs) --> bottom of FPR to fuel return line. Is that how it is plumbed? Other variations are possible, but this is the common setup -- really you just need to be sure that the fuel pump feeds the rails and then the FPR comes after the rails in the flow path and that you are using the correct ports on the FPR. And are you sure you have correctly identified the hard lines coming up from the bottom of the car? It would be easy to mix those up. Also, where in the system do you have the pressure gauge (is it on/connected to the front of the FPR)?

For the resistors, they should be in series with the fuel injectors from a circuit standpoint. And what resistance (ohms) are you using?

-Max

boostracingfd

fuel lines are plumbed exactly how u described but i will check the feed lnes to make sure i did not reverse them, i also just capped of the one that goes to the charchol can , at least i hope i got the right ones. i do have a set of 1000cc injectors, do you think i should try those in the secondaries to see if it makes a diffrence?

maxcooper

Trying the 1000 cc/min secondaries should help to determine if it is the secondary size setting or a general transition problem, but you should be able to run the "1600"s as secondaries once everything is sorted out. If it is worth the swap to make the determination, go for it, but I would expect that you'll have to swap them back before your tuning session. I don't see any reason why you couldn't run the 1000s as primaries with the proper tuning as well. I know other people have done it, and I am running 850 primaries on my car without any major issues (rich idle, but I think I just need to set the lag lower and tune the rest of the map accordingly).

-Max

boostracingfd

will try a cople of suggestions il post later with the results

boostracingfd

do any of u think it could be power imput to the fuel pump? Is it possible becuase all the sensors and switches and things that have to do with the twin turbo have been removed could cause a problem

boostracingfd

bump

maxcooper

Not likely -- the two-speed fuel pump control setup seems to be largely unrelated to all the other sensors, etc. in the car. Unless the fuel pump wiring itself is damaged, I don't think anything else would affect it.

-Max

boostracingfd

yhanks that elliminates that issue