AusS2000

Sitting on top of the fuel rail is a small mushroom type device that is a fuel pressure damper. I guess it smooths out spikes in fuel pressure.

When my tuner last had at the car he removed it and installed a tap for a fuel pressure gauge.

I'm wondering how important the damper is and what negative side effects I would see with it removed.

Slows2k

I wouldn't worry with it to much Aus. Plenty of pre-OBDII Honda's came equipped without a damper, using a standard banjo bolt set up.

xviper

I cannot answer your question directly but this is my take on the subject. This pulsation damper is like a pressure relief valve for water pumps (like on our fire pumper trucks) to prevent "water hammer" (when a hose line is suddenly closed), but in this case, I guess you can call it "fuel hammer". The fuel system is designed to hold a prescribed pressure in the fuel rail when an injector is opened and sprays. However, when an injector shuts off, there is a "hammer" effect that causes (as you already mentioned) a sudden pressure spike in the fuel rail. Without this "relief valve", the next injector to open would get a much higher pressure than what was intended.
I'm not saying that I know for sure what happens in a fuel rail (as my knowledge base only applies to the hydrodynamics of water pumps), but I'm going to make an educated guess and say that without this damper, there is a likelihood that the air/fuel could be a bit more rich than with the damper. Whether this "richness" is enough to be a negative, I cannot say.

slipstream444

Xviper is right. It does exactly what its name implies ... it dampens changes in fuel pressure.
We can all theorize what can and may happen if you remove the damper, but there are so many factors related to a steady state fuel pressure that I would never touch it. Doing so may be self-critiquing.
Also, keep in mind that your alternator is constantly switching between a charging state and an 'off' state (11.9V-14.3V). This in turn changes the voltage the fuel pump sees at any given time ... which in turn will possibly create a slight variation in fuel pressure. The damper probably keeps this and any number of variations from causing performance issues.

slipstream444

Xviper hit it right on the head, its main purpose is to dampen the injector pulsation feedback.

For note: If there were pre ODBII cars not fitted with the damper (I've never seen one without one??) they probably were running a much lower fuel pressure slow2k.

Careful about suggestions and blanket statements.
This car is pushing conventional limits, including fuel pressure, and you can't compare it to a pre ODBII engine.

My parents had an old Volvo that had one of the first electronic FI systems - pre ODB, and it had a damper.

AusS2000

Keep in mind that MY2000 Aus S2000s are not ODBII! Caught me out big time when I ordered an ODBII cable and couldn't find where to plug it in.

The problem I have is major bucking when cruising at 3000rpm and asking for a small throttle increase. I have been wondering if this was in any way related to the lack of damper but I guess not.

Kobe

removing the damper must surely change the pressure in the fuel rail...and I thought a fuel injection system is totally dependent on pressure/time relationship...i.e. only timing is used to "measure" the fuel as opposed to a meter....and a change in expected pressure would surely alter the amount of fuel passing through the injector.

davidb

I can't speak from personal experience but on other car lists they are adding much larger fuel dampers than we have to cars who have never had fuel dampers and they all swear about how they smooth out the A/F tuning issues.

Another biggie is dual inlet or center inlet fuel lines

Slows2k

[QUOTE]Originally posted by slipstream444
Xviper hit it right on the head, its main purpose is to dampen the injector pulsation feedback.

For note: If there were pre ODBII cars not fitted with the damper (I've never seen one without one??) they probably were running a much lower fuel pressure slow2k.

xviper

Your car is "blown", right? I suppose you could put the damper back in and then go for a drive and see. However, I'm going to guess that this won't solve your problem. You might want to look into your MAP connections that were made when the S/C went in.
It wouldn't hurt then to do the "MAP whack", ECU reset. If this does nothing, consider borrowing another MAP sensor from a good running car and seeing what this does. Sometimes, as I've seen with another recent S/C installation, a bad MAP sensor can be "masked" by other modifications and it might not be the first thing one thinks of. In that case, a new MAP sensor fixed a similar (but not identical) problem.