Lean Spot At ~2400 RPM...What the?
11-02-2010, 09:20 AM
#161
I installed the new adapter this weekend. I have not done any serious data logging yet, but from driving the car for the last three days, it seems as though the little stutters I would sometimes still get around 2000 and 3000 (on the tach, so actually like 2200 and 3200) at very low loads are gone now. When I get a chance, I will try to take a datalog and see what the A/F trace looks like now.
But for now I am happy with the way it is running and I have done all I can, short of adding a third damper. I am going to leave it the way it is and move on with fine tuning (on a dyno) probably in the spring. I just got a Haltech dual wideband and an IQ3 dash so I am going to install those over the winter.
If anyone is interested, I may be able to produce a limited number of the adapters, now that the CNC programming is all done. PM me.
11-03-2010, 09:48 AM
#163
my car has the same 2500ish rpm issue actually. Mine isnt leaning, but it definitely hesistates/bucks when going thru those load cells.
Sharif couldnt tune it out either. Super annoying actually because 70mph is ~2500 rpms in 6th gear. So the car would continuously hesitate as the cruise control would modulate the speed around 2500 rpms and hi vacuum....
argh. Add that to the cam phasing problem that other 2003 users are having makes me wonder whats up with 2003 G35's
Sharif couldnt tune it out either. Super annoying actually because 70mph is ~2500 rpms in 6th gear. So the car would continuously hesitate as the cruise control would modulate the speed around 2500 rpms and hi vacuum....
argh. Add that to the cam phasing problem that other 2003 users are having makes me wonder whats up with 2003 G35's
Did you ever find a solution to your issue?
11-05-2010, 11:57 AM
#165
when get under my intake manifold next time, we are going to try a fuel line update. going to run the feed lines to the front of the rail, and use much shorter lines off the back of the rails to the regulator. should help the regulator dampen. going to build it on my car, but probably just ship it to you to try it since im parting out mine anyway.
03-18-2011, 10:05 AM
#168
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So if I've read all 9 pages correctly... the only people having this issue have return systems? I'm trying to help a friend with their 05 turbo'd G (Osiris tune) and with a modified stock system (same as the OP used to confirm the problem with the modified system, winny bro and all) they are still having the ~2400 hesitation. The car leans out to ~ 17:1 on their PLX and the wideband 02's confirm this when reading the Osiris logs... the car can be tuned so that it will run ok but then it runs really fat at idle and cruise speeds... any help is greatly appreciated. It seems almost impossible to get it in closed loop... is it possible they messed up the stock regulator when modifying it and that's the problem?
Last edited by rbsileighty; 03-18-2011 at 10:07 AM.
03-23-2011, 12:51 PM
#171
I don't understand why one cannot simply insert a fuel dampener inline with the feed lines to the rails. I know space is tight - is that the only issue or do they restrict flow? 
Maybe where the hard line ends? That's probably too far away from the injectors to dampen the effect of injectors closing and opening. Perhaps using oversized, low latency injectors is another mechanism to minimize the pulses (and this is why my HKS 1000 cc injectors in my CJM stage 2 cause only minimal lean spikes ). It was kind of a pain to tune out, but with 100 rpm resolution below 2k rpms, it's possible.
Maybe where the hard line ends? That's probably too far away from the injectors to dampen the effect of injectors closing and opening. Perhaps using oversized, low latency injectors is another mechanism to minimize the pulses (and this is why my HKS 1000 cc injectors in my CJM stage 2 cause only minimal lean spikes ). It was kind of a pain to tune out, but with 100 rpm resolution below 2k rpms, it's possible.
Last edited by rcdash; 03-23-2011 at 01:06 PM.
03-23-2011, 01:10 PM
#172
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I don't understand why one cannot simply insert a fuel dampener inline with the feed lines to the rails. I know space is tight - is that the only issue or do they restrict flow? Maybe where the hard line ends? That's probably too far away from the injectors to dampen the effect of injectors closing and opening. Perhaps using oversized, low latency injectors is another mechanism to minimize the pulses (and this is why my HKS 1000 cc injectors in my CJM stage 2 cause only minimal lean spikes ). It was kind of a pain to tune out, but with 100 rpm resolution below 2k rpms, it's possible.
Maybe where the hard line ends? That's probably too far away from the injectors to dampen the effect of injectors closing and opening. Perhaps using oversized, low latency injectors is another mechanism to minimize the pulses (and this is why my HKS 1000 cc injectors in my CJM stage 2 cause only minimal lean spikes ). It was kind of a pain to tune out, but with 100 rpm resolution below 2k rpms, it's possible.
03-23-2011, 03:01 PM
#173
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I'm VERY close to taking the plunge on some of the Marren dampers and making them fit as the lean spots are annoying the crap out of me! I've taken the measurements and although it will be pretty tight with the T pieces in place I think it will fit. Would need to get replacements for the two small lines that go into the Y adaptor though as I don't think they will reach.
I spoke with Charles just a few days ago and in the next couple of weeks he's going to try re-routing the fuel lines to the rail so they are fed from the back hoping the Aeromotive damper will damper the pulses.
Matt
I spoke with Charles just a few days ago and in the next couple of weeks he's going to try re-routing the fuel lines to the rail so they are fed from the back hoping the Aeromotive damper will damper the pulses.
Matt
03-24-2011, 05:21 AM
#175
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that looks perfect and should fit on our rails. I wil check the clearance between the rails and plenum sometime this weekend.
It sucks that it's 114$. That's 228$ for the package of them. I'm wondering if i can add the T fitting between the 2 return lines and my FPR so it will be sitting right on the firewall. Plenty of room there.
It sucks that it's 114$. That's 228$ for the package of them. I'm wondering if i can add the T fitting between the 2 return lines and my FPR so it will be sitting right on the firewall. Plenty of room there.
03-24-2011, 09:39 AM
#178
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how much was your cost in making the new lines? I assume with the lack of flexibility of those lines you had to make new supply and return lines for the setup.
03-24-2011, 04:05 PM
#180
the problem with adding a damper inline isnt that its difficult, its that its difficult to do CLEAN and simple. Making it even more of a pain in the butt, is the 1/2x20 thread (-5) of our fuel rails, and the lack of variety of fittings for it. every single way i have thought of adding the stock ones to our rails using already available fittings is just too messy and bulky, and thats how i feel about the Merrin ones also.
Since this is a problem that seems to effect less than 1% of cars with RFS, i believe that just about any change of the dynamics in the layout can probably have an effect. The only other factor here, is that this could be a witch-hunt. Since "mx594" is the only person to ever add a damper to a RFS, at this point its too early to say for sure that fuel pressure pulsations are even the problem that some of us have in common.
I think that the line swap is probably the best bet. After all, having the front of the rails lead to the regulator is quite a long journey back, and its not going to allow the regulator to do much dampening or respond to it quickly enough.
Now that winter is coming to an end, I can get my 350z out of storage and over the shop pretty soon. We are going to take off the intake manifold and everything, and that will be the perfect chance to size up the flow reversal hoses.
Since this is a problem that seems to effect less than 1% of cars with RFS, i believe that just about any change of the dynamics in the layout can probably have an effect. The only other factor here, is that this could be a witch-hunt. Since "mx594" is the only person to ever add a damper to a RFS, at this point its too early to say for sure that fuel pressure pulsations are even the problem that some of us have in common.
I think that the line swap is probably the best bet. After all, having the front of the rails lead to the regulator is quite a long journey back, and its not going to allow the regulator to do much dampening or respond to it quickly enough.
Now that winter is coming to an end, I can get my 350z out of storage and over the shop pretty soon. We are going to take off the intake manifold and everything, and that will be the perfect chance to size up the flow reversal hoses.