Adjustable Fuel Pressure Regulator

[New2DSM2]

Hi again guys and gals
I have a stupid question and I have searched through the forums for 3 days straight and can't really find the simple answer I am looking for here.

Question is: Why do I need an AFPR? I know that sounds dumb, but I like to know the why of things before I do them. Having said that, take a look at my vehicle profile which is up to date and someone please tell me why I need an AFPR. I have been told many times to get one but no one can tell me why.

My A/F ratio is solid at WOT at 12.0-12.1 just where Dan Buschur and Jarrod tuned it to on the dyno, I don't have any hesitation problems or stuttering, basically no problems whatsoever (other than wanting it to go faster) but people keep asking me, "Dude, where's your FPR? You have a 255LPH fuel pump and no FPR?!?!"

Someone please tell me WHY!

I am not opposed to buying something new for my car, just want to know if it is truly necessary.

Thanks!

 

[99gst_racer]

If you cannot maintain a constant and consistent base fuel pressure at idle, then you need one. If your's is maintaining itself, then you're OK.

The rest of you're information is trivial. Have you tested your fuel pressure yet?

 

[donmagicjuan]

Try narrowing the scope of your search to thread titles only and you'll find answers much more easily. This is a frequently recurring topic, and a search for "255 AFPR" turns up a lot of useful threads. Here's an example: http://www.dsmtuners.com/forums/showthread.php?t=77449&highlight=255+afpr

You will hear people say the stock regulator is overrun at idle. When the injectors are not open for very long, the pump outflows the regulator, causing pressure to spike high in the fuel rail. The high pressure results in excessively rich AFRs during these conditions, which can make tuning a not-so-fun experience.

As Paul suggested, checking your fuel pressure at idle is a good way to tell if you need one. If it is abnormally high, then you should get one.

 

[New2DSM2]

Try narrowing the scope of your search to thread titles only and you'll find answers much more easily. This is a frequently recurring topic, and a search for "255 AFPR" turns up a lot of useful threads. Here's an example: http://www.dsmtuners.com/forums/showthread.php?t=77449&highlight=255+afpr

You will hear people say the stock regulator is overrun at idle. When the injectors are not open for very long, the pump outflows the regulator, causing pressure to spike high in the fuel rail. The high pressure results in excessively rich AFRs during these conditions, which can make tuning a not-so-fun experience.

As Paul suggested, checking your fuel pressure at idle is a good way to tell if you need one. If it is abnormally high, then you should get one.

These are the 'whys' I was speaking of, thanks guys that helps clear it up alot and makes sense to me now.

Great to have people with this kind of experience to guide noobs like me through.
Thanks for the fast responses and the wealth of knowledge.