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My POS...any ideas?
- Thread starter boostedmach
- Start date
Is it normal for pressure not to rise as boost rises? As gufi said that is a huge flucuation 2-3psi. That can definitely cause what is happening. I took a couple lbs of fuel pressure out of my previous car while running N20 and guess what happened..........POOF! Blown head gasket and melted sparkplug electrodes right off!
Figure out why the pressure is bouncing around.
Check the ground to the fuel pumps.
boostedmach
Well-Known Member
Im going to the hobby shop once it opens, Im also checking the pro racer forums to see if my fuel pressure activity is normal, In the datalog cpu is raising the voltage to the pumps to a peak of like 10.5 volts to try and keep up with the injectors...mabey somthing in the fuel pump voltage table.
Is that not a tuneable parameter? It can't be normal for fuel pressure to fluctuate that much.
boostedmach
Well-Known Member
Well Iv been reading some
..."The FRPS (fuel rail pressure sensor) subtracts the boost, or adds the vacuum, from the FP to maintain 40psi across the injectors..."
I dont think its a fuel problem, because the A/F ratio is decent, we are just trying to find out what causing this problem.
Think it might be spark related...soo Im gonna check everything today, Coils (might put stockers in..alot of people have had problems with these WeaponX), Read plugs, check MAF.
I know for sure its not belt slip, nor is it my Bypass valve.
You do have a regulator. It's in the tank with the fuel pumps. Returnless sytems are designed to run at a "constant pressure" and your's isn't doing that. If I add and take away fuel by 2-3lbs on any car as it's accelerating it is going to do what your car is doing. I don't care if it's carburated!
What you have to do is find out if it's mechanical or electrical causing it. Have you tried tuning with the stock pulley? I still don't think your fuel supply line is big enough. Go to a return style fuel system. Returnless sucks!
Are you sure the rail sensor you spoke of is good? I was reading that if you hit the rev limiter it can wax that sensor.
Sometimes a low pressure or volume problem isn't the fuel pump but a clogged filter, plugged fuel inlet filter sock, "restricted fuel line" or a faulty fuel pressure regulator. A low voltage supply to the fuel pump due to a wiring problem, low charging voltage or bad relay may also prevent the pump from operating at normal speed.
What you have to do is find out if it's mechanical or electrical causing it. Have you tried tuning with the stock pulley? I still don't think your fuel supply line is big enough. Go to a return style fuel system. Returnless sucks!
Are you sure the rail sensor you spoke of is good? I was reading that if you hit the rev limiter it can wax that sensor.
Sometimes a low pressure or volume problem isn't the fuel pump but a clogged filter, plugged fuel inlet filter sock, "restricted fuel line" or a faulty fuel pressure regulator. A low voltage supply to the fuel pump due to a wiring problem, low charging voltage or bad relay may also prevent the pump from operating at normal speed.
02gt
Well-Known Member
i'd have to ask, have you data logged the fuel pressure with the x cal yet, run down the street under boost, record the fuel pressure and see what happens...
He has logged it and it's jumping around from 38-43lbs. That's 5lbs difference !!!!!!!!!!!!
02gt
Well-Known Member
yeah i'd say there's something off, like you said start checking the simple stuff first.....
Please explain your method of checking plugs. You mean for detonation?
boostedmach
Well-Known Member
Well, I found the problem... #6 Coil is burned up...got so hot it started to melt the epoxy it was encased in...smelt like an electrical fire....plugs look like new...cause they are...brand new Auto Lite Racing
boostedmach
Well-Known Member
Got a set of good stock coils (thanks cornboy) And now its back to dantes, gonna head there this sat. Needs to finish the tune, and hopefully this has solved my problems.
Good luck with the 5psi fluctuation in fuel pressure. I hope you can get it tuned. I'm frustrated and it's not even my car, lol!
crossbreedgt
Well-Known Member
huh that must be the same prob that 4.6stangpower has with his 98GT. im gonna let him try my coil packs and see if it works
hay boosted,,, you may not take it from bobby, but let me tell you dude,,, that fluctuation is not good!!!! those return style systems are shi*t!!! call procharger or any one else!!! boosting 101 man!!! that line is way wya too small to give you the fuel you need!!! and the returnless system further hurts you!!! you can run 8-12 lbs half way decently with a returnless system!!! theres no way that youll hit the power you want with that fuel system!!! it just wont hold together man!!!! get rid of the returnless and install a return system!!! its not hard at all!!!! and with that everything is mechanical!! you dont have to wory about how your fuel pump is fluctuating!!! im telling you dude!! youre gonna fry the thing and starve your motor,,,, and that 5 psi fluctuation is a contributor to your problem,,, i guarantee it!!! it may not be the only thing,,, but its definately a problem!!!i wouldnt push it with that set up man!!!! just dont do it!!! id hate to see you destroy everything that youve put so much money into!!!!
boostedmach
Well-Known Member
Well will see, first thing is first, taking care of this bad coil, Then I'll start looking at the fuel, The tune is not even done yet, and Its been having problems, so you cant really look at everything on the datalog when the car is missing and breaking up on the dyno.
There ARE limits of a returnless system, and im not there yet. Might end up running a bigger feed line, but im not going return quite yet.
Also, on another note, I think im going to have to dig through my harness because I think I have an electrical problem leading to me screwing up my coils...we will see come Friday and Sat.....Im pretty sure I just screwed up some more coils!:nonono:
boostedmach
Well-Known Member
Not a set just one, and If there is a ground from the coil driver, i guess anything can happen...gonna take a look at it in depth tomorrow.
crossbreedgt
Well-Known Member
let me know how that goes.. i think im not gonna lend my coil packs for testing purposes anymore