Ian's 99 build thread
#282
Thought on everything you just posted:
NA miata's had no damper, but had regulator on fuel rail.
NB miatas' had regulator far from fuel rail, and had a damper close to fuel rail.
Doesn't a fuel pressure regulator act as a damper in some way? If so having it closer to the fuel rail would help.
Just some thoughts, I dunno I've never measured fuel pressure on my car.
One last point- in the same log you just posted, AFRs are rock solid. I wonder if the AFRs between cylinders are too?
NA miata's had no damper, but had regulator on fuel rail.
NB miatas' had regulator far from fuel rail, and had a damper close to fuel rail.
Doesn't a fuel pressure regulator act as a damper in some way? If so having it closer to the fuel rail would help.
Just some thoughts, I dunno I've never measured fuel pressure on my car.
One last point- in the same log you just posted, AFRs are rock solid. I wonder if the AFRs between cylinders are too?
#284
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Thought on everything you just posted:
NA miata's had no damper, but had regulator on fuel rail.
NB miatas' had regulator far from fuel rail, and had a damper close to fuel rail.
Doesn't a fuel pressure regulator act as a damper in some way? If so having it closer to the fuel rail would help.
Just some thoughts, I dunno I've never measured fuel pressure on my car.
One last point- in the same log you just posted, AFRs are rock solid. I wonder if the AFRs between cylinders are too?
NA miata's had no damper, but had regulator on fuel rail.
NB miatas' had regulator far from fuel rail, and had a damper close to fuel rail.
Doesn't a fuel pressure regulator act as a damper in some way? If so having it closer to the fuel rail would help.
Just some thoughts, I dunno I've never measured fuel pressure on my car.
One last point- in the same log you just posted, AFRs are rock solid. I wonder if the AFRs between cylinders are too?
AIUI, wideband O2 sensors don't have the response time of a lot of other sensors. The fuel pressure sensor I'm using will do 1KHz, widebands aren't anything like that. That's part of the reason it appears more solid, but yeah, I'm concerned about pressure drop for individual injectors making individual cylinders go lean.
--Ian
#285
I will continue fuel discussion in your new thread: https://www.miataturbo.net/engine-pe...5/#post1244814
#295
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When I first installed it, I did not hook up the vacuum reference. Later, I did, as you can see in the photos in post #275.
I talked to FM about why they recommended not referencing it, they said that because it's a long run from the manifold to the regulator, the regulator will lag the boost rise and it can make lean tip-in worse. They also suggested that at 12-15 psi (standard FM2 levels of boost) the referencing isn't really necessary, because with a base pressure of 60 psi it's still getting 45 psi pushing the fuel through. I'm running a teensy bit more than 12-15 psi (currently set at 24, gonna see if it'll do 30 once I get it to the dyno). That means there would only 2 bars pushing fuel through the injectors, which is a bit low.
Thus, I ran the vacuum reference line.
--Ian
I talked to FM about why they recommended not referencing it, they said that because it's a long run from the manifold to the regulator, the regulator will lag the boost rise and it can make lean tip-in worse. They also suggested that at 12-15 psi (standard FM2 levels of boost) the referencing isn't really necessary, because with a base pressure of 60 psi it's still getting 45 psi pushing the fuel through. I'm running a teensy bit more than 12-15 psi (currently set at 24, gonna see if it'll do 30 once I get it to the dyno). That means there would only 2 bars pushing fuel through the injectors, which is a bit low.
Thus, I ran the vacuum reference line.
--Ian
#297
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So things on the Miata got stalled for a couple of weeks. We got the keys to our new house, and I spent a couple of weekends doing stuff related to that, rather than the Miata. A nice big, paved side yard perfect for trailer storage!
Today, however, I got back to looking at the fuel, and plumbed in the Radium pulse damper. I decided to mount it on the rubber mounts from the factory pulse damper, so first I needed a bracket. (This is actually the second bracket, the first one turned out to not be long enough). It's just 1/8" thick 2" aluminum angle with a few holes and a corner chopped off to make room for the 90-degree hose end.
Then the FPD mounts on the bracket with some loose hose ends to check for alignment.
The pressure sender remote-mount hose needed to be flipped around, so the 90 is now next to the sender.
Hoses made and fitted:
Feed lines:
So ideally I want the pulse damper mounted in the feed line to the rail, but right now it's actually mounted in the remote line for the pressure sensor, because I didn't have the right fittings to do it properly. I'll order those and reroute it later, but right now it works very well indeed. The pressure swings are maxing out at around +/- 2 psi, vs the 15 psi I was seeing before. Yes, the pressure sender probably isn't seeing everything that's happening at the rail due to the routing right now, but I did have the damper in the feed line briefly (just hacked up for testing) and it looked the same there. The weird ringing at idle is totally gone, and I'm VERY pleased with it.
So my takeaway from this is that FM's big fuel kit needs a pulse damper. I don't know if the stock damper would accomplish the same thing, or if it really needs to be the fancy vacuum-referenced radium one.
The car will now do a 270 kpa run to redline smoothly, without the major stumbling I was seeing before, although there is still a little blip in that datalog which may be a misfire. 270 kpa is probably asking a lot of the Toyota COPs.
--Ian
Today, however, I got back to looking at the fuel, and plumbed in the Radium pulse damper. I decided to mount it on the rubber mounts from the factory pulse damper, so first I needed a bracket. (This is actually the second bracket, the first one turned out to not be long enough). It's just 1/8" thick 2" aluminum angle with a few holes and a corner chopped off to make room for the 90-degree hose end.
Then the FPD mounts on the bracket with some loose hose ends to check for alignment.
The pressure sender remote-mount hose needed to be flipped around, so the 90 is now next to the sender.
Hoses made and fitted:
Feed lines:
So ideally I want the pulse damper mounted in the feed line to the rail, but right now it's actually mounted in the remote line for the pressure sensor, because I didn't have the right fittings to do it properly. I'll order those and reroute it later, but right now it works very well indeed. The pressure swings are maxing out at around +/- 2 psi, vs the 15 psi I was seeing before. Yes, the pressure sender probably isn't seeing everything that's happening at the rail due to the routing right now, but I did have the damper in the feed line briefly (just hacked up for testing) and it looked the same there. The weird ringing at idle is totally gone, and I'm VERY pleased with it.
So my takeaway from this is that FM's big fuel kit needs a pulse damper. I don't know if the stock damper would accomplish the same thing, or if it really needs to be the fancy vacuum-referenced radium one.
The car will now do a 270 kpa run to redline smoothly, without the major stumbling I was seeing before, although there is still a little blip in that datalog which may be a misfire. 270 kpa is probably asking a lot of the Toyota COPs.
--Ian
#300
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Making a -6 return style system would've required a lot of new hose and fittings that I don't have, several hundred dollars' worth. It would also preclude the use of the stock rail, requiring a lot more parts to be swapped out for California's biannual "regulatory" reasons.
--Ian
--Ian