fuel system

[prove_it]

Quoting belize1334:
Prove_It: You are spreading false information. Due some research on the subject before you start commenting.

At high loads there is no issue since you're using most of the fuel coming from the pump so the regulator is only having to bypass a small volume. The issue is driveability at low loads when you're not using much fuel. Then the regulator is having to bypass most of it. With a large pump this is an issue because the orifice is too small and the fuel pressure becomes uncontrollably high. If you have a speed density setup it doesn't matter since you tune based on load and rpm anyway and those are the things that will affect the overrun condition. BUT, if you're running an airflow type ECU (like the stock ECU or MAFT or ECMLink) you will not be able to tune it out and you WILL have to get an AFPR to make it work.



By the way I'm an ASE certified tech with 6 years experience and worked in two performance shops and have tuned many many cars. Also graduated from WyoTech. Took the right classes and have done the research. I have done my research. Also I have experience. Don't be a brat.

 

[jepherz]

Quoting belize1334:
Prove_It: You are spreading false information. Due some research on the subject before you start commenting.

At high loads there is no issue since you're using most of the fuel coming from the pump so the regulator is only having to bypass a small volume. The issue is driveability at low loads when you're not using much fuel. Then the regulator is having to bypass most of it. With a large pump this is an issue because the orifice is too small and the fuel pressure becomes uncontrollably high. If you have a speed density setup it doesn't matter since you tune based on load and rpm anyway and those are the things that will affect the overrun condition. BUT, if you're running an airflow type ECU (like the stock ECU or MAFT or ECMLink) you will not be able to tune it out and you WILL have to get an AFPR to make it work.



I'm not sure how running MAP has anything to do with it, can you be more specific? The stock MAF setup is tuned on rpm vs. load, so your statement doesn't really hold water. There will always be the case of more fuel flowing than the AFPR can return to the tank, so there is always a possibility of high pressure produced at the injectors which isn't going to be directly related to the pressure in your intake or elsewhere.

 

[icurunnin]

Quoting mountaineerjeff:
well my 550s fell through, and I thought I found a set of evo 560s but that didnt go as planned either. I threw up a WTB ad. but anyone got a set of old evo 560s around? I thought Id have a set so I got keydiver making a chip for them. I got 135, but thats it, so i need like 20 to get new seals. somebody help me out.

pm sent

 

[belize1334]

If you wanted to you could tune a car on MAP to run on a rising rate fuel pressure or fixed fuel pressure or really any fuel pressure curve you want just so long as you always got the same fuel pressure at a given RPM and LOAD (psi). That way EVERYTHING in sight depends on the the same parameters. I'm not saying it's the right way, but it is doable.
An overruning fpr will satisfy this condition because fpr overrun WILL be determined based on LOAD (the pressure that the regulator references to) and fuel consumed. Fuel consumption is itself is a function of LOAD and Volumetric Efficency, which is in turn a function of RPM. So if you're running on MAP, you CAN tune around fpr overrun, my friend did it on his 400whp st-185 and still got 25mpg on the freeway with a full standalone ECU running on MAP.

The problem with AFM or MAF (be it hotwire or Hz or whatever) is that they don't use pressure as one of the reference parameters. They use RPM and Airflow. Airflow is closely related to pressure but there isn't an exact dependence so the fuel pressure will depend on a parameter that is not accounted for in the tables. Thus you have not completely specified everything and you cannot get a consistent tune. The only situation in which this is not true is if the functional fuel pressure (i.e. with respect to the manifold pressure) is always fixed. In this case, because it is a constant, you don't need the missing parameter (manifold pressure) because the dependence on that variable is trivial, i.e. there is no dependence.

 

[mountaineerjeff]

^ thanks, im getting a AFPR its just I had the pump already, and havent got to get the AFPR yet.

 

[91GSR]

Quote:


By the way I'm an ASE certified tech with 6 years experience and worked in two performance shops and have tuned many many cars. Also graduated from WyoTech. Took the right classes and have done the research. I have done my research. Also I have experience. Don't be a brat.



i think the problem is that you have been working on 1g and 2g DSMs...these cars are not DSMs and from the little knowledge that i have about both different cars there are A LOT of differences. so even if you have seen something work on a DSM doesn't mean it will work on a VR-4

 

[mountaineerjeff]

on top of that, there is no reason to ever act like you know everything. just cause it worked for you and not someone else, doesnt mean that either of you are wrong. there are alot of variables with 20yr old cars. and +1000 on galant vr4. they arent dsms.