I get back from new zealand may 5th and i can send mine out asap charles. My car is in pieces at the moment because i'm rebuilding my engine. I'll probably be down another month of so depending the time it takes for the machine shop. Hit me up on the email and we'll get it worked out. I know i have 1 oem damper. I'll have to snag the second one when i head home after new zealand.

also, i'm curious how these dampers are going to fit inside of that smashed area. do you have a mock up or idea of how it would work?

 

i was looking today and there is just no way to mod our existing rails for it... we machine away too material everywhere to make them clean and compact, theres nowhere thick enough left to get the damper inlet in there.

we are currently sold out of rails, material is on the way. next week we will be machining them. perhaps we should make an alternate program for a few prototype sets for you two to try on.

 

APS has huge dampers at the ends of their rails. havent seen one in person though to notice how much clearance they have...

 

Those are actually the regulator. They use tiny little Bosch non-adjustable regulators.

 

Perhaps a tee where the hard line connects up? That is way upstream, but it should dampen any pulses originating at the fuel pump...

 

Fuel pulsations come from their injectors opening and closing. Similar to pulses in an intake manifold from the valves opening and closing. Our goal will be to get directly into the rail bore

 

Let the record show that I too have an 03 G35. Except my injectors are tiny compared to your guys' - only 600's.

I have somewhat of an update: Now that I have dual widebands I am able to see the A/F on each bank. One thing I have noticed is that I am still getting a lean condition on the passenger side of the engine, but NOT the drivers side. That explains why I can sometimes still feel a hint of hesitation while driving, but never saw it on the wideband because I was only monitoring the drivers side.

I have not verified the severity of the lean spot on the pass. side yet since i haven't had a chance to do a tuning session, but I can tell you that I see numbers in the 16:1 range around the same ~2400 rpm. Which is nowhere near the severity that I was seeing on the drivers side before I reinstalled the damper, but it is still a lean spot.

I wonder if the damper on the feed line has gone bad? Maybe I will install a new one just to make sure.

 

i went back to stock injectors/ stock EMS (fuel return system though, no way to go back to stock) and my hesitation is still there around 2000 rpms. The huge injectors only magnified the problem, which would also suggest some sort of resonance event

 

Holy crapola.

Look at this datalog. The lean spots on Bank 1 are worse than I thought - O2 control must have done a good job of smoothing them out?!?! I am hitting 18:1 at 2020 rpm, 17.7:1 at 2444 rpm, and 19.5:1 at 3045 rpm with dips down to 14:1 in between (green line)!!! This is way worse than I thought.

Meanwhile, bank 2 (blue line) almost never goes above 15.5:1 or below 14.5:1

It's no wonder I still felt hesitation at 2400 rpm - adding the damper back onto the bank 2 fuel rail only fixed half the problem. One side of the engine is running great, the other is still running like ****!

Again this log was taken by accelerating very slowly in 4th gear and trying to hold the engine at -17.5" in-hg. I repeated the same exercise at -11 in-hg and the resonance is non-existent, with both sides of the engine running smoothly and close to target A/F from 1200 to 4000 rpm.

I will be ordering a new feed line damper assembly ASAP. Maybe mine is bad and that exacerbated the problem in the first place?

 

ya i only feel mine as well at very low loads, like rolling down the street, leaving stop lights, or chugging gears

 

I use 100 rpm increments (sometimes 50 rpm) to tune out the fluctuations. Here are some images of my fueling compensations using the Haltech at the exact same load (-7 in Hg *** EDIT oops I see I should've done -17 in Hg - crap. Well even here you can see fluctuations):



I have a CJM stage 2 RFS, 1000cc HKS low impedence injectors, and single walbro with a KB BAS set to boost voltage at 4 psi up to 16.5 volts.

EDIT: Ok, here it the graph at -17 inHg... lots of extra fuel needs to be dumped at 3200 rpms to maintain afr

 

Those plots look strikingly similar to my A/F ratio curve...

Looks like you have some resonance issues my friend. Do you see that on both banks? I suspect you would if you have removed both dampers.

I ordered a replacement damper for the feed line. I am hoping mine is bad. If not, I am going to have to find a way to get another damper in there...

Question: would an HR fuel rail assembly fit on the DE? With modification? The reason I ask is becuase the HR has a total of 3 fuel dampers, one on each rail and one on the feed!

 

That is my fueling, not AFR, but I get your meaning. My AFR is not perfect (gear dependent a bit), but with closed loop it's not bad - 13 - 15 throughout. Having a lot of resolution with the Haltech gets around any driveability issues... It's just a pain dialing in the tune and you have to leave it a little bit on the rich side.

 

so MX, what is your current fuel setup now? back to stock, non-return setup?

Here's a vid of what mine is doing with the big injectors
http://www.youtube.com/watch?v=5ASOcDuDsqY

 

Holy crap. That is a horrible stutter. God only knows how poorly distributed the fuel is to each cylinder when that happens - at least it only happens in vacuum...

 

There may not be room for the stock fuel damper, but what about this (dimensions are present as a link here http://www.whipplesuperchargers.com/pdf/3bardamp.pdf):

http://www.whipplesuperchargers.com/...sp?ProdID=1196

 

ya i can still feel it with the stock injectors, but the car was completely undrivable before.

so the car will just sit some more until something can be figured out. Tuning and the associated travel costs are just too high to keep guessing at it.

Hopefully the CEL reflash stuff really works to pass cars thru inspection.

 

Nope, still running the stage 0 return with my custom made adapter which allows me to keep the damper. Also running Deatschwerks 600s and a Walbro 255.

 

is your damper before or after the rails? i think stock is before the rails. its super easy to T a Marren in before the rails, so I am going to try that for the time being while CJM works on a on-rail solution.

 

Stock has two dampers. One before the rails on the feed line and one at the very end of the rail. So in my case it's not easy to tee in another damper. If I could put a damper anywhere it would be in the crossover tube between the rails, or at the very end of the first rail...just like Nissan did on the HR.