Hey anyone... regarding the fuel pulsation dampner.... mine is fairly new ( 4 years old) and when working in my engine today, the plastic cap popped off in my hand and there was a small screw that was sitting loose in the cap.... now i know what was rattling around in there.... anyone know why this happened? what is the purpose of the screw?]

Edit.. after searching more ive found conflicting comments, one says the screw tightened lets fuel in, and loosened, resricts fuel.... And one says tightening will ruin the dampner.... now im more confused

 

Tightening the screw won't do anything but maybe stop the leak for a few days before the screw pops on out again. Grab yourself the Banjo Bolt from the rear end of an S4 fuel rail, get the washers from Mazda for the Pulsation Damper and do the swap. I know you probably think the Banjo Bolt Mod is too controversial to risk on your car, but trust me, it's fine. And then you never have to worry about the damn P.D. leaking ever again...

 

That is incorrect. The screw is a guide screw to prevent the PD from bottoming out. And stays in control.

You should never attempt to replace the screw, but rather it is time to replace the PD.

This is how the S4 PD works:


Fuel injected cars come with PDs for a reason.

Replacing the PD with a new one means another 10 years or 100K miles without an issue and the fuel injection runs correct.

 

Aside from the questionability of the mod.... i did some testing of my own and found this.... with no screw, at least for the 2 min i drove it, it drove a lot better than before ( as in, with the screw tightened, and halfway in, i was getting huge amounts of hesitation, like 1/4 power.... then i took it out, and it drove great... now knowing that its not a good idea to run the car with no screw.... i wont do it again... but just out of interest... why does it run better with no screw? and if it backed itself out... then why? is this the reason the fires occur? .. the screw falls out, and then eventually the pd fails, and spurts gas?

 

kinda shot the ten year thing down huh

 

Ten year, as in that it should last ten years? haha, if so, then im not getting another one from mazdatrix. thats where the last one was from....

But really.. could I have messed this one my self..? the only thing ive done to it specifically was removed it and re-tightened it while doing my emissions removal.... i vaguely remember someone saying that you shouldn't tighten it too much.... but that may of course been in regards to the screw, not the PD itself, into the fuel rail...

 

Just do the banjo bolt mod. You'll be fine.

 

I would say replace it with a new one. Icemark is right; it is there for a reason. Its purpose is to absorb the vibrations in the rail caused by the injectors opening and closing. I have read about fuel starvation problems at upper boost and rpm ranges with no PD.

 

I would opt for the pneumatic-type PD instead of constantly replacing it.

Basically it is a tube that is sealed on the top, and mounted to the the highest point in the system. It will trap a pocket of air in it and the air will absorb the pulsations.

 

a classic example of what happens when there is not a PD

Probably because you didn't set it to the correct depth. How do you know that halfway in is the correct depth (or that you were half way in)? They are set at the factory based off the diaphragm tension at rest.

 

Properlly installed, and not tampered with, the S4 PD typically lasts 10 years or about 100K miles.

If the PD has been tampered with (such as the screw removed and re-installed) the PD should be replaced. It is not longer set correctly and will fail. No if's ands or but's. It will fail in sort order. Even if only 1 year has gone by. Another way that they fail is when people remove the cap, and dust or other contaminants can get to the screw or even worse... blocks the screws cap. That also increases the failure rate.

 

So mark.... heres my question, since installed, 4 years ago.... it hasnt been touched nor cap removed, save last week, when i removed the entire dampener itself from the fuel rail.... could i have tightened it back down too hard onto to fuel rail? because other than that, ive never touched it, and NEVER touched the screw.... The only other thing that i could see affecting it, was that after i reinstalled the LIM and UIM ect.... the car wouldn't start for days... until i used ATF and starter fluid.... could the constant cranking have ruined it? Thanks for your input.. it is mucho appreciato...

 

Please stop claiming things that are just downright false.


-Ted

 

Please stop posting such nonsense.


-Ted

 

The dude is asking questions, not stating fact.

 

So by adjusting the screw on the PD, it's supposed to affect driveability?
Are you supporting such a claim?


-Ted

 

replace the PD with a banjo bolt so it's no longer a problem. sure, a new PD could last 10 years, also could last 6 weeks. that's a gamble I'm not taking.


If you need a banjo bolt to eliminate the PD just PM me. I can send you one for $10 shipped.

 

I find it hard to believe as well, though weirder things have happened. I'm supporting only that you attacked some guy after he voiced questions about a supposed solution/band-aid. That's not classy.

 

I was just describing my experience, as we've already discovered, this PD is shot.... so i drove it around the block under 3 different scenarios... the first, the screw fully tightened, the second, the screw loosened to what felt like halfway, and the 3rd- no screw at all..... on the first 2 drives, the car hesitated like crazy, and the 3rd drive, it ran strong, no hesitations. Im not saying that i would ever really drive a car with no PD screw, or that anyone else should EVER... im just describing my experience with a PD that we all assume needs to be replaced. Why these things happened, i dont know.... what im trying to find out is WHY they happened... aka....did i do this myself? or did the PD fail by itself....? I want to know what i can do differently in the future....

 

No, it is just NOT POSSIBLE.

You can heatsoak the engine, and it will cause the same experience.

To be pointing the finger at the PD is just plain ignorant.

It's like saying you tightened youy lug nut 5 lb-ft more, and the car handled better!

Total bullshit.


-Ted

 

How exactly is it false? That is the method residential plumbers have been using for decades to solve water hammer in homes. Only recently has it been phased out since the trapped air dissolves into the water and the chamber and it becomes waterlogged. (key search word: plumbing air chamber)

There may be something I haven't thought of with this, but it seems perfectly reasonable that a trapped pocket of gas will absorb large pulsations in an otherwise incompressible liquid system. I guess I'm just curious of an explanation of your strong response, and I hope this will cause a semi-productive debate for once.

Edit: Ted, we can chat on aim if you want to keep out the clutter.

 

Sorry.... hop on a plane, and come on over... ill even cook you a hot dog. I just tried this whole thing all over again... no screw, no hesitations. Screw in, then backed it out a half turn... i even stalled the car twice just trying to get into first, because the engine jerked so much with any throttle. I dont mean to claim the impossible, but it just what im finding, perhaps some other factors are at play here, i admit that the car has been acting up ever since last week when i pulled my thermal wax and did the TB mod... and it was a beast to start.... BUT, when i did, it drove fine.... only after a bit did it start to hesitate... but then i adjusted the TPS using a DMM and it smoothed out nicely....

BUT .... i still just want to know? what causes a PD to fail.... and when i say fail.. i mean.... the screw backed itself out and was loose in the cap.

 

Those who like to claim that "water hammer" effect have no idea how the fuel system works.
The fuel system does not dead-end anywhere.
So how can you claim it's the same phenomenon?

If you have air bubbles in the fuel rails, you have bigger problems than the PD.
There is NOT SUPPOSED TO BE ANY AIR IN THE FUEL SYSTEM.


-Ted

 

I tell you what...
You have a dyno close by?
How about to adjust the PD as much as you want...do back-to-back-to-back dyno pulls, and I'LL PAY for the dyno runs?
We'll see if there is any difference?

I don't call just because the screw fell out = failure.
I call LEAKING GAS = failure.


-Ted

 

well... since im afraid to drive the car with no screw... because as Mark said .......

"If the PD has been tampered with (such as the screw removed and re-installed) the PD should be replaced. It is not longer set correctly and will fail. No if's ands or but's. It will fail in sort order."

And when the screw is in, the car is so bogged down that it feels like its running on 1/4 power.... i give it gas and it goes nowhere... Getting to a dyno would be pretty hard untill i replace the PD. And seemingly pointless, because my grandmother could tell me somethings up with my car when i cruise by going 5 mph... at 4000 rpms...... You see what i mean? and im not saying that the PD is the primary problem. im well aware that it could be the PD in concert with some other untuned gremlin.... i dont know . but imma run down to Atkins today and pick up a spare PD, and then ill find out....