j9fd3s

iTrader: (3)

that was really good!

the third thing, if i may add it, is that they wrote the manual in Japanese and then translated it into English. so they say noise, but it might not be a literal translation. also if you've ever head the fuel system pulsate, it is really loud, if you've ever heard house plumbing do a water hammer type thing it does sound like that.

the second housekeeping item is that there are ~3 or 4 versions of the S5 T2, the Japanese, the USA, with and without the cold start assist and then the European version with its extra FPR (for reasons). so the vacuum hoses in the back of the upper intake vary a little between versions, and then the US has the AWS and the PS idle up solenoid. not sure what version the vacuum routing is, or what your version is, but its best practice to pull the hose off at both ends and make sure it goes where its supposed too!

ok the funny story, my old boss used to work for Alfa Romeo, and they wrote their manuals in Italian, and then sent them to some un-named college here, and the Italian students translated them. so every month when the new price books showed up, there was a group phone call to laugh about the butchered translations.

peejay

The fansubs of the second season of Initial D after Takumi blew the engine up were hilarious!

TeamRX8

iTrader: (2)

like springs on the suspension, if you make changes to the fueling system the damper that was previously on there may not actually be in control/tuned for where it’s needed after the changes

thousands of wankel race engines run without a MOP. There was big fuss made over on RX8Club many moons ago about Renesis engines going boom or losing compression on premix without the MOP. One racer started the whole thing claiming that, but it was directly in contrast with the long-running Mazda Pro Formula race series using the Renesis on premix.

My favorite Renesis engine vid just to add a break from all this wankel fuel system wankering-on

.

peejay

If you really want to be concerned about the exact fuel pressure differential across the injector, every injector would have its own regulator referenced to the intake runner where the injector is. This would also require each injector have its own pump.
what is the air pressure in the runner versus where the regulator gets its feed? Note that the primary and secondary halves of the intake manifold may also have different pressures.

To some extent, engineering follows fashion. Bearings used to have tangs to locate them, modern engines do not. The tangs are only necessary to make manual assembly faster, the bearings are held in place by crush fit. (rotary engine building tip: Grind the tangs off of rotor bearings before you press them in. They are a liability in case the e-shaft grabs the bearing and spins it, which no tang is going to stop, but a tang WILL give you negative clearance if that happens)

But in WWII aircraft engines, the bearings had locating dowels. Were the engineers morons for using these pointless devices? Of course not, but they were also working with what were currently common practices.

On the flip side, Flathead Fords had floating rod bearings. No press fit. They had clearance on both sides like a turbo bearing.

gsmithrx7

Basically each of the cars exhibiting obvious symptoms that caused misfiring and hesitation would have 2,3, or 4 different engine speeds that were "hot spots" perceived to be about ~20-30RPM wide. These were spots where pressure oscillation amplitude was bad enough (with anti-nodes overlapping injector firing events) that no fuel table adjustment would correct the problem to satisfaction. Plus, the EMS doesnt really have the fuel table resolution to combat such small window problems. So, if you were extremely slowly climbing in engine speed, or trying to maintain speed at one of these indicated RPMs, the car would misfire and buck.

I had my car buck once, slowly accelerating up a slight hill. The above information about these "hot spots" answer some of my questions and make sense. I was not running a PD at the time. After reading the threads about PD's I have come to the conclusion that if you have a Turbo, it is of great benefit to have a PD (or two!) in the fuel system. If you have a N/A engine you don't really need one because it operates at a much lower power band. If my new engine starts to buck I will install a PD.

I also found out that the screw and o-ring actually move in and out of the housing as the diaphragm moves, interesting.

rlynchster

Herko Fuel Pressure Damper PR4188 for S4 N/A cars.

All metal construction for 55 bucks on amazon. . .. . . Why wouldn't you use one at that price?

This is simply a pressure drop problem. . . . . . .Fuel injectors want a known, and optimal, P1 inlet pressure and P2 outlet pressure to work at optimal performance. . . .Run outside that window and you risk delivery rates that are out of spec and/or droplet size issues.. . .The pressure dampner is there to help you stay in that window.

gsmithrx7

I went on eBay and as soon as I saw that there was no screw hole to leak from I purchased it for $57.77! Just have to put my finger on it a couple times a year to see if is still pulsating.

Wish you posted this sooner, a lot of back and forth for no reason. But I learned a great deal about my fuel system, thanks everyone for posting!

maaaaackle

iTrader: (1)

Thank you for posting this!

I think most peoples issues with the FPD is that it cost $175 from Mazda. lol

gsmithrx7

I received the damper and compared it to the original one I have, the untreaded area is shorter on the new one. This area supports the inlet banjo, so only half of the banjo is supported. This does not bother me, it is the same length where it screws into the rail.

What is a concern is that the special crush washer was not included!

$4.00 from Atkins.

I had a couple, so I am reusing one of them.

gsmithrx7

I found this photo on line.



Please replace your damper with one that can't leak fuel onto your engine!