well i ordered the Marren damper and will try at the the Y that feeds both rails and see how it does. I might also try Y'ing the output of both rails again and putting a damper there as well.

we'll have to see what CJM comes up with. rails with dampers are next in the machining queue.

 

question, do we all have g35 ecus?

 

so i'll try this before the fuel rails for now, like the stock setup.

 

awesome!

 

well believe it or not, last night i took off the intake manifold and collector, etc. from my 350z. were using it to figure out exactly where on the rail we want to try mounting the damper for a batch of dampened rails.

 

yay charles!

 

Installed the new feed tube/damper assy last night and went for a drive. No difference. Waste of 75 bucks!

So it's back to the drawing board. I want to add a third damper to the system, on the bank #1 fuel rail. Just like the HR.

Charles - I would like to make a recommendation. If you are going to build rails that incorporate dampers, use the HR dampers. They are much cheaper than the damper on the DE rail ($24 vs. $75) and they also look like they could be integrated in a smaller overall package. See diagram.

If you made a set of drop-in replacement DE rails (keep the stock feed line hookup) that had an HR style damper on each one, and a port for a return line, I would buy them.

In the mean time I think I can use the extra adapter that I had made and find a roundabout way to install a second damper right where the feed line bolts to the fuel rail. That should make it quite similar to the HR setup. Anybody got a spare feed tube asssembly that I can buy off them?

 

what the feed tube assembly? #1 in your diagram?


so right now you have 1 damper before the rails and then 1 after the rails (like the de setup in your diagram)? and that didnt work?

i got my marren installed but havent put the intake manifold back on yet.

 

Part number 17520 in the first diagram. I need one to modify.

Yes I have both dampers in place. I think I have discovered why Nissan added a third damper to the HR

 

hopefully Charles can weld those flanges onto his rails to mount those HR dampers. That would be great.

Non-return systems need a lot damping. You dont read much about return systems needing it. MOst everyone concludes that a FPR is sufficient. Hate being different

 

So why is the VQ different? Is it becuase the FPR in our return systems is not mounted directly to the rail as it is on most factory return fuel systems? Or could it have something to do with the cylinder firing order and the distance between the injectors on the rail?

Str8dum1 - Was it not possible to mount the Marren damper directly on the rail? I don't know how effective it will be if there is a long fuel line between the damper and the rails.

 

no way to mount on the rails directly. its too big and there isnt enough spacer between the rear of the rail and the firewall (without spending a good bit on fittings with trial and error), at least the way I have my FPR mounted, and I dont have room to move it anywhere else.

if i ran a length of fuel line to the damper and remote mounted, it could be done. The only way for rail mounting for me would be flange on the rail like the HR.

its not much length difference than the stock setup with the feed tube. i figure if i dont see any difference, i can invest more time and relocate. I just used the parts I had laying around.

 

I appreciate the feedback. I was actually wondering what the prices were like on the dampers for the sake of everyone having to purchase them.

The HR dampers mount sorta strange, and it may prove to be a little bit of a hassle to machine. This could still go either way. The HR ones are defininately less expensive, but when I look at it I really see just a $25 difference since DE owners would have to buy 2 HR for $50 versus one DE for $75. Then again, im sure lots of guys have already ditched their stock parts. I personally prefer the HR one, but due to its mounting method it may be too much extra machine time/effort.

i really hope to get this done quickly, I am pushing as hard as I can... we are currently shopping for another CNC as we are finally in the shape to be able to purchase one and the two we have are always so tied up lately that its really hurting us.

i appreciate your guys understanding and willingness to try your own solutions as well. your results are what have steered us to just go for the dampened rails instead of messing around with fixes.

BTW mx, I do apologize for missing deadlines on getting your custom fitting made. i mean nothing but the best when i tell people when we can do things in a specific time span, but i often am too optimistic on what i can expect in terms of availability of our CNCs.

 

MX still seems to have issue with the stock location 2 damper setup though, correct?

 

Correct. I seemed to have fixed half the problem. Bank 2 (the bank with the damper right on the rail) is perfect. Bank 1 still has resonance. There is a damper on the feed "junction" but it doesn't seem to be enough. That's why I am going to find a way to mount a third damper directly onto the #1 rail. I just need to find someone who wants to get rid of some stock fuel system parts so I can play around with it.

But honestly, it drives well enough now that most people wouldn't even notice it. Before it was pretty bad. Now I am just chasing that "last 10%". There is a big difference between 3 cylinders going lean and all 6 cylinders going lean. O2 control helps mask the problem as well.

 

Well I have just discovered this thread and think I may be suffering the same problems! I'm running a Vortech though.

I'm getting a very lean spot between 3000 and 3500rpm while on part throttle.

Every thing was running fine but decided to upgrade my fuelling for extra safety. (Kind of wish I hadn't now)

A few weeks back I fitted AAM basic RFS, Walbro 255 and DW600cc injectors (all bought 2nd hand from here)

I ditched the SST box and changed to Uprev. On the drive home from the tuner post Uprev, when I was cruising on the motorway, I noticed it was hesitant when accelerating between 3k and 3.5k on part throttle. I have an AFR guage (fitted to the 2,4,6 bank) and this was showing 17:1 +.

I could accelerate through it in lower gears and not notice it so much but it was still there.

I went back to the Tuner and he had a tweak on the part throttle areas of the map but we couldn't get it to replicate the issue and all seemed fine. But driving home again after about 50 miles of sitting at around 3k in 6th the problem was back!

Over the last few days it got steadily worse to the point where it sounded a bit like a misfire even when revving with no load. This obviously worried me and spoke to my tuner.
I pulled the plugs and did a compression test to be safe and it was fine. The plugs are in reasonable condition but show some signs of running lean.

I sent the injectors for testing and one of them was supplying about 30% less fuel than the others and cleaning hasn't solved it. Obviously this is a problem that needs sorting but after reading this thread I'm not convinced it was my only problem.
Would a faulty injector only show up for a few hundred revs and work fine the rest of the rev range? Or is this a separate problem?


My RFS set up is including the two OEM dampeners in their stock locations but due to my Kinetix SSV being in the way of the bulkhead I've had to locate the FPR by the brake reservoir See pic), this means that the hose to it is about 3 times longer than the supplied one.



Could this extra length in the pipe be compounding the dampening issues?

It does sound like this may have been my original problem and that this had led me to find the injector going bad.

What are your thoughts?

 

The kinetix are notorious for leaking. I'd get that injector fixed and do a smoke test before throwing more money at things. I kind of doubt you have the same issue as in this thread -- I've got the exact same setup (AAM basic, 255lph, 600CC DW) and none of these issues.

 

Sounds like fuel got hot with the new RFS and after driving awhile. The stock ECU reads fuel temp but I don't believe it compensates for it (other than perhaps adjusting the gas gauge) because the stock setup does not incorporate a RFS. With a RFS, fuel temps skyrocket and I have personally logged dramatic (like 20% swing in fueling) AFR changes on long highway trips before/after filling up a tank of (cold) gas.

EDIT: I've been meaning to ask Hal about read stock fuel temp via CAN and compensating for it, but honestly Haltech closed loop O2 control can compensate for all these issues and you at most get only momentary or slightly lean conditions.

 

Stock ECU does closed loop corrections for everything except WOT basically .. the short term trims would likely compensate as needed. I've never had any issues like this.

 

Yeah the injector is my first concern, I will sort that first but if it don't fix the problem I may well be suffering the posted problem, It just gives me something else to consider. I appreciate that you may not have the same problems with the same setup but it does only appear to be a small percentage that do.
Thanks for the heads up on the SSV, I will make sure its correctly sealed and torqued when re-fitting.

rcdash - Does the fuel temp really make that much difference? On my UK car there wasn't even a fuel temp sensor on the pump hanger from the factory so I don't know where it would have got fuel temp readings from. I've replaced it with a US one that does have a sensor fitted but not sure if the wiring is in the loom for it. How would you get round this issue? just lagging the pipework?