do i need a FPR ?????

[gotgrip666]

hey guys sobody told me i should be using an adjustable fpr because i have the walbro 255 fuel pump i allso have 650 injectors and stuff , the guy said im over running the stock fpr is this true? and is it causing performance problems?

 

[andymoraitis]

That's absolutely correct. Either install an AFPR, or step down to a 190 pump and you can ditch the AFPR and not overrun the stock regulator.

Hope that helps,

Andy

 

[oldman]

That's absolutely correct. Either install an AFPR, or step down to a 190 pump and you can ditch the AFPR and not overrun the stock regulator.

And that would be correct except that 190 will still overrun the stock fpr, just not nearly as bad as the 255. Hey Andy, how's the project coming along.

 

[gotgrip666]

cool thanks alot guys im gonna order one asap, one more thing would this be causeing my car to cut off when i rev it high and just let off the gas? and this happens when coming to a stop to if i just push in the clutch and dont down shift

 

[andymoraitis]

And that would be correct except that 190 will still overrun the stock fpr, just not nearly as bad as the 255. Hey Andy, how's the project coming along.

Let me correct myself then. First of all, glad to see they made you a wise man, even though you are over the hill. I'll PM you as to project status in a few.

Cheers!

Andy

 

[VBGSX]

cool thanks alot guys im gonna order one asap, one more thing would this be causeing my car to cut off when i rev it high and just let off the gas? and this happens when coming to a stop to if i just push in the clutch and dont down shift

This problem could be a bad ISC motor.
Do you have a multimeter(volt meter)?
If so, here's how to test it
http://dmtalon.v8eaters.com/ISC.html

 

[yangtech]

after reading this i think i might need to order an afpr too...

 

[oldman]

cool thanks alot guys im gonna order one asap, one more thing would this be causeing my car to cut off when i rev it high and just let off the gas? and this happens when coming to a stop to if i just push in the clutch and dont down shift

Overrun happens during part throttle and idle before the system is able to use up the extra fuel. Yes, your problem could very well be related to the fpr overrun but not limited to.

 

[gotgrip666]

after reading this i think i might need to order an afpr too...

is there any certain setting i should have it on or what is the circumstances i should adjust it to?i ordered this one free shiping i think im gonna order a new fuel rail to soon and possibly some 800 injectors and a new dsmlink disc and cable because of the bastards who stole my cd case

 

[GSTinMS]

I ordered one too. Put on a 255 lph last night. What pressure should I run it on? Stock injectors.

 

[oldman]

I must be getting old but I can't see which afpr both you bought, I certainly hope it isn't the CommendFlo. Read through this link and you should understand how to check for leaks and set your base pressure according to the year of your car.

 

[andymoraitis]

Stock for a 2G is 43 psi.

 

[GSTinMS]

It was the Commandflo

 

[oldman]

It was the Commandflo

Not good. Commendflo only allow you to adjust the pressure up but not down which does nothing to help you with an overrun situation. If it's not too late, return it and spend a little more for a real one. You should have done some search before you purchase, you would have found this info easily as it has been discussed many times before.

 

[never2muchBoost]

afpr is not neccesary, u can bandage the overrun problem up with a afc. u can lean it out that way, it may be a little harder to tune, but definitely do-able. 660s, 255HP, safc, and no afpr and my car runs fine. i'd say just get it if u have the extra cash to spend, i dont in my case but everything is working out fine

 

[Burnett03]

the safc will no keep the pump from overruning the stock regulator. Not unless it has some feature that i dont know that makes it so the stock regulator can bypass more fuel at idle/mid throttle? You just think the safc is fixing your problem, but its really not!

 

[andymoraitis]

afpr is not neccesary, u can bandage the overrun problem up with a afc. u can lean it out that way, it may be a little harder to tune, but definitely do-able. 660s, 255HP, safc, and no afpr and my car runs fine. i'd say just get it if u have the extra cash to spend, i dont in my case but everything is working out fine

I'm sorry, but that's just not the right way to tune. I'll bet if you put that thing on the dyno, the A/F would be way on the rich side until the boost picked up enough to cancel the overrun. Not to be argumentative, but there's a big difference between running fine and running a correct and optimal tune.

Just my 2 cents,

Andy

 

[never2muchBoost]

well im not running rich so it's doing something, as long as your *true* a/f ratio (wideband) is stoichiometric (not rich or lean) than yr fine, just takes u a little longer to tune without the afpr

 

[Burnett03]

I'm sorry, but that's just not the right way to tune. I'll bet if you put that thing on the dyno, the A/F would be way on the rich side until the boost picked up enough to cancel the overrun. Not to be argumentative, but there's a big difference between running fine and running a correct and optimal tune.

Just my 2 cents,

Andy

word. andy knows his stuff, as do i..

 

[never2muchBoost]

listen guys, im not putting the afpr down, it is definitely a useful part for tuning, etc. and if u have the money for it then definitely get it, i want one and will get one when i have the cash, im just saying u dont need one and im saying that from personal experiences. my fuel pressure is definitely higher than it should be and i know that, but with a afc u can *bandage* it up, not fix

 

[andymoraitis]

word. andy knows his stuff, as do i..

Oh crap, now you jinxed me. Let's just say I'm learning something new every day, but thanks for the vote of confidence.

Be good and let me know how that chip is,

Andy

 

[steve]

Im just saying u dont need one and im saying that from personal experiences. my fuel pressure is definitely higher than it should be and i know that, but with a afc u can *bandage* it up, not fix

You just explained why you do need one.

You can't tune out the problems from overrun with an SAFC. All you can do is bandage up the worst parts but it can't do anything about the regulator overrunning everytime you back off the throttle or that overrun isn't RPM based but load based. Within a set of NE points that the SAFC deals with your regulator could be online one second and overrunning another based solely on how much excess fuel the engine is consuming. Some of this is splitting hairs because the difference in fuel pressure can be minor but the whole FI system is designed around the idea that the fuel pressure tracks manifold pressure 1:1 without spikes and blobs in it's response from overrun.

The only fix to FPR overrun is a FPR that doesn't overrun or a way to control the fuel pump volume like the resistors used to drop the pump voltage on a 3/S TT. So if your DSM fuel pump overruns the stock FPR you need a replacement FPR.

Steve

 

[eclipsegsxccca]

With 650's and 255 walbro I'm suprised you dont already have a good fpr. They aren't to expensive and you will need one sooner or later.

 

[oldman]

Holly crap what did I miss? ! steve, you should write a tech article about this so we wouldn't have this discussion as often as we do.

 

[put2gether]

cool thanks alot guys im gonna order one asap, one more thing would this be causeing my car to cut off when i rev it high and just let off the gas? and this happens when coming to a stop to if i just push in the clutch and dont down shift

Are you venting your BOV? That exact same thing happens to some cars when you vent without a blow thru setup.