I heard that the s5 primary fuel rail is much safer than the s4 as the PD normally doesnt break on the s5. I got the s5 rail put on the car but now the car stalls at about 1200 rpm. https://www.nopistons.com/forums/pub...1047683561.gif Do I have to ajust the mixture for the new fuel rail? I also hear a loud hissing sound from the intake manifold. https://www.nopistons.com/forums/pub...1047683561.gif I cant find any vacuum leaks. Any idea what could cause this?



Thnx

Andy

Hissing from the intake manifold https://www.nopistons.com/forums/pub...IR#>/blink.png



sounds like a vaccum leak to me.



That could be why you are dying at 1200. Your motor is getting too much air and it can't compinsate that by adding fuel since the air ins't being measured through the AFM. So in other words, lots of air + no fuel = no run

I cant find any obvoius leaks. Ill check again though. Any other Ideas?

Thnx

Andy

shoulda just got a new pd for your rails.



with s5's you have to replace the whole rail to replace the PD when it goes out, which is why ive had a leaky PD forever, i dont feel like replacing the whole rail to fix it.



i was trying to switch to s4 t2 rails forever but now ive got a full custom fuel setup going in so thatll fix those problems.



kevin.

Is there a generic PD you can buy anywhere and adapt it? I don't feel like spending like $150 on a stock FC PD..

a lot of other mazdas/hondas/acuras use the same damper

its 7 bolts in total to replace the primary rail bro





2 on the rail....5 to get the uim off

yea but the price of replacing the whole rail just to replace the pd is higher then i look to spend. id rather save it and spend it on my new rails.



kevin.

sweet https://www.nopistons.com/forums/pub...IR#>/smile.png



just to clarify I'm talking s4...

I heard that the PD on the s5 pretty much never goes and the s4 was practically guaranteed to go. If not, maybe Ill just go back to the s4. I dont know what the fuel rail could do to the intake but thats my only guess.

Thnx

Andy

Figured it out, I think.

The pd on the s5 fuel rail was blown. When I tried to blow through the s4 rail there was a lot of resistance to the flow, however, on the s5 rail there was no resistance at all. I figured the lack of idle and the stalling could be caused by low fuel pressure. The loud hissing noise I heard was fuel flowing freely through the rails. Swapped the Pri. rail back to stock and she runs great. https://www.nopistons.com/forums/pub...IR#>/smile.png



Does anyone know anything about the reliability difference between the s4 and s5 rail? The s5 looks better to me but if the pd on the s5 fails just as often as on the s4 then there is no point in me getting an s5 rail for my car.



Thnx

Andy

I dont think that there is a real difference between the 2. I dunno though. Through my experiences so far, the S4 works great for me. I am pounding 60 psi all the time for a while and no probs yet. My car also has 95K on it. But new fuel setup soon so I wont have it much longer.

the s4 you can remove and replace the pd

s5 the pd is built into the unit basically, so to replace the pd you buy a whole new rail and PD.



a suggested move is to use a Marren Pulsation Dampener (injector.com) and make it work on the s5 rail do-able with the proper taps, but not done very often.



Ill be swapping toc ustom rails and FPR basically to avoid dealing with replacing a crappy design with the same stock crappy design.



the PD is like a bomb waiting to go off.



kevin.

I just deleted the pd on the black t2 tonight. Swapped the banjo fitting and bolt opposite from the opposite side of the pd from a different rail...

Are you having any problems with not having a PD? It seems to me like the PD helps keep the fuel pressure up and without it the fuel pressure will always be low. At least I think that was my problem.

I will let you know when its running. Bigturbo74 did it on his car...

i doubt the PD would lower your fuel pressure, in my random thoughts at least.



but hey, its all possible, hell my motor mount was ******* up my wastegate.



kevin.