We can totally do it if there is interest.

MJ

 

Build it and you can count me in for one, in a New York Minute.

 

i would be interested!!!

 

ditto

 

mj, w/ all the electrical components you've developed/improved in the past, i'm surprised you haven't jumped on this one....I always thought this was an unbreakable code or something...

I'm sure most of us carry spares in the trunk...I'd rather spend money on a bullet proof one...

I'm a yes for sure!!!

ok guys, speak up, let the man know you want this...

 

Its not really necessary to modify the electronics because you can do that in the tune. If someone made a mechanical one that was slower to react on the boost side it might help. I played around with making a thing i thought would work but did not. It consisted of a T at the FRPS air connection and another T a couple inches down. The 2 T parts were connected by 2 pieces of tubing so it was a one into two into one format. On one half I put a one way valve so it would only allow boost thru it. On the other side i put a needle valve to allow the vacuum signal and bleed boost after a shift. It was too hard to dial in the needle valve and get consistent fuel pressure so i scrapped the idea. I was looking for something anybody with the hesitation could just slap on over their crappy tune, but it would also reduce the delta pressures the wimpy diaphragm sees and reduce breakage. (If it was tuned right you wouldn't have a problem). I'm sure it can be done with the right equipment, but you need all metal parts in the system because my plastic ones were melting before i switched to metal.

 

i'd buy two

 

what does the FRPS actually do? When it sees an amount of fuel pressure, what does the EEC do w/ that info? If the FRPS needs to see precise changes in fuel pressure, i'm wondering if a "bleed off" system would be tough to work w/. Bleeding off boost is tough to control precisely. As an example, even the best manual boost controllers for turbos that bleed off boost can sometimes cause the boost to spike. These manual boost controllers are the most accurate you can get w/ a needle bleed valve...

But again, I don't really know exactly what the function of an FRPS is so I may be way off base...Maybe the FRPS doesn't need to accurately record fuel pressure and tricking the boost it sees would work...

 

what does the FRPS actually do?

The FRPS is basically a diaphragm with fuel pressure on one side and MAP on the other side so it measures pressure drop across the injectors (takes MAP into account like a regular fuel pressure regulator). If you are at 10psi of boost and let off all the way it goes to -10psi which compounds the "apparent" fuel pressure spike by a 20psi delta. If you can keep the boost in there just until you complete the shift the spike will be reduced by 20psi. It does need to be very accurate and yes, the bleed off was tricky. If you have it open enough to get a good vacuum signal then it bleeds off the boost too quickly. Also there is no danger of pressure spikes like on a turbo because the bleed off is very low volume and is not controlling boost in any way.

 

Don't know if anyone has ever posted pics, but here are some of what actually "blows" in the FRPS. The pic is of the electronic portion of the FRPS. There is a thin plastic membrane at the bottom of the hole you see and a tiny pin hole in the middle that covers some sort of sensor. That tiny pinhole is also what dumps fuel into your engine when it blows...

 

me too. I blew 5 before i split each fuel pump off and ran -8 to the front. Since then i havnt blown one but i still keep spares under the pass seat. I would buy one if a good product was made also. so



+1

 

n0xlf...what's that blown section made of? Is it metal, plastic, wood lol? If it's metal than there should be any number of ways to reinforce it. But has anyone thought about what causes them to blow and what would happen if it didn't blow when needed to. What potential damage would occur if the FRPS needed to "pop" but couldn't? This is most likely a retarded question because I can answer it myself, but I just wanted some input that maybe I haven't thought of.

 

n0xlf, thanks for the pix...i've never seen a blown one before....what happened when you blew it? Rev limiter?

Does anyone know what fuel pressure these break at? Is it caused by a huge spike in fuel pressure?

MJ needs a bunch of interest...so post up in here!!!

 

That blown part is some sort of flexible membrane, the consistency of a latex glove (a little thicker). You really couldn't do anything to reinforce it because the pressure of the fuel against it is what the sensor is reading (the movement of the membrane itself), so if you change that, you would get incorrect readings...

Mine blew when starting my car, nothing special...Left me stranded in a parking lot...

 

If you want to read all about the technology in that blown part, here it is: http://archives.sensorsmag.com/articles/0101/50/index.htm

Warning, it is pretty technical.

 

Count me in MJ. Let me know if there is anything I can do.

-Graycen

 

Ill take one as well

 

from what broke7 mentioned in the other forum, there can be 2 types of failures...failure w/ the electronics and failure w/ the membrane as seen in the picture above...

http://www.svtperformance.com/forums/showthread.php?t=438305

I wonder if the electronics failure is due to high fuel pressures also...

 

Count me in for two.

 

It is my understanding that they fail when there is a large pressure spike created across the membrane when the one bounces off of the rev limiter. I think it was someone from KB that likened this to a water hammer. I seem to recall something posted awhile back on a method to help prevent them from rupturing, but I can't remember any of the details. (Something to do with the PPRV perhaps? It sucks getting old...I can't remember things anymore, LOL!)

markolson - Interesting article. So then I would gather the actual structure of the FRPS consists of a thick rubber or silicone membrane, (or the like) covering the actual silicon piezo sensor. It would be cool to look at one under a microscope to see.

 

It is my understanding that they fail when there is a large pressure spike created across the membrane when the one bounces off of the rev limiter. I think it was someone from KB that likened this to a water hammer. I seem to recall something posted awhile back on a method to help prevent them from rupturing, but I can't remember any of the details. (Something to do with the PPRV perhaps? It sucks getting old...I can't remember things anymore, LOL!)

markolson - Interesting article. So then I would gather the actual structure of the FRPS consists of a thick rubber or silicone membrane, (or the like) covering the actual silicon piezo sensor. It would be cool to look at one under a microscope to see.

I have never had one blow by hitting the rev limiter, they have blown between 4-5k rpm but at high boost (25-28 psi).

 

I havn't poped one yet but I have a spare in the trunk. I'd be up for a improved one as well. When it lets go I guess the car will just fall on it's face??

 

has anyone popped one with the kenny bell disc in there?

 

If you have aftermarked fuel rails such as CPR's you cannot use the disc that Benne Bell sells unfortnantely. And most of the FRPS failures occur with high boost whipples and KB's.

 

I would be interested in an upgraded sensor

 

This was something we were thinking about as well. I don't think we are going to bother with it but from the limited time we had looking at it the KB disk reduces the amount of pressure present at any given time. Or should I say, reduces the pressure spikes and slows sensor response which salvages the sensor from the PID control overshooting it's setpoint.

The problem with the disk, that we thought we found, is that the FRPS is slower to respond and reports different readings then it should be.

I agree with Trick Tuner. If the tune was setup so that the PID control in the tune wasn't so aggressive (as not to overshoot pressure) there would be less issues of the FRPS blowing. Only problem is at higher HP levels it's harder to set the PID control because of the greater demands of the fuel system. This can however be overcome by purchasing bigger pumps.

 

The problem with the disk, that we thought we found, is that the FRPS is slower to respond and reports different readings then it should be.

if you could market it such that it would be "more durable but just as sensitive as stock", I wonder if it would sell...also, educate the newer owners of it's problems...if it could serve both low HP and big HP people alike...start up a thread and see what kind of reaction you'd get...

another thought..instead of selling a brand new frps...why can't a better material be used than the KB disk...is the KB disk made out of foam, i've never seen one? why not make it more like a rubberized or silicone membrane that would be more accurate to pressure differences...

 

Part of the hammer effect is due to the boost pressure on the back side of the diaphragm. If you go from 20psi of boost to -10 psi of vacuum ("slow shift") it adds a 30psi spike to the fuel pressure. I worked on a device with a one way valve and a bleed valve so that boost would go into the FRPS thru the one way valve, but would stay in there for a second to dampen the boost portion of the FP spike. It did not work as designed so i gave up.

 

This is something we never took into account. Then again we looked at it maybe for a day at best.

I'd say you guys should look at how much friggin money KB has made on a .5 cent piece of whatever it is...it's a band aid fix and it sells...and alot of people that probably don't even need it, buy it anyways...if this is a bandaid then so is the BF IRS brace...it too adds support for a known weak OEM part...nothing wrong w/ bandaids...

Remember, over engineering sells every single time when it comes to this hobby...especially if it's a known problem w/ our cars...whether it's a disk that ups KB's or a stronger FRPS, I'd buy it purely for reassurance...even if I've tuned the pressure spikes out...and I don't even plan on pushing this car as hard as some do...

I admit that a bigger badder FRPS may work but will that only last so long as it is not the real problem? I don't know because not enough testing has been done meaning that a new FRPS might be totally in vein. My point being, I'd hate to invest $50,000 in new sensors, have our customers buy them and still have the same issue. Slow and steady, develop and test wins the race.

In any case, this is not a knock against any tuners out there, but the first thing I would check would be PID on failed vehicles. This is a big bottleneck for us as most tuners don't give out their tunes. My first assumption would be that most tuners have PID setup incorrectly. I wouldn't feel bad because some of the biggest companies in the world have a hard time setting up PID control properly for their machinery. Infact engineers are dedicated to tuning PID processes.

Let me show you guys a picture.

Lets say the blue line is fuel pump "processor set point" When we mash the gas or let off the gas the processor commands a new set point. Now not all is well in fuel delivery land. Here is where PID control takes charge.

A properly tuned system is like the yellow line. Quick to react but with minimal overshoot. VERY HARD TO TUNE FOR!!!

In a badly tuned system what could happen is the magenta line. Infact it could look even worse than what I drew there. Here is an example where PID is tuned improperly and is badly overshooting it's set point value. Now what happens is a "hammer effect" which may potentially pop the diaphragm. Also keep in mind that through shifts this hammer effect is happening over and over.

Let me say first hand that PID is a bitch to setup right. I've done it on a couple processes and knowing if it really is optimal is almost impossible without some big time math calculations. If you guys look into that and find it's not the problem maybe we can look at other areas of failure. If we find that the source is the FRPS it may be worthwhile for us to invest but not until all areas are explored. Could you guys think what a bitch it would be if we made a FRPS and a tuner develops a PID to prevent this? Goodbye investment.

Personally if it can be fixed in the tune it's better for everybody so it's better to check these things than not.

I'd like to add that the fuel delivery characteristics of different pumps may also change the PID function. This means that every new or added pump should be cause to check the PID. More or less fuel delivery demands may also be causes to re-tune PID. I've noticed on Mustangs that I have tuned in the past that fuel pressure sometimes went to ZERO because of PID overshoot between shifts.

 

anyone know how i can go about ordering the KB disk?

 

Hey any tuners have the PID variables on hand for a couple different vehicles. Say a 99 Mustang GT and an 03 Mustang Cobra? I'm going to see if I can emulate the PID output for the pumps using matlab.

 

I have found that it totally depends on the fuel requirements as well as the fuel system and boost levels. I looked into some of the PID calculations and the problem is there are a couple unknown constants needed for emulation of the PID functions. One thing I have not tried, but think may work great, is to remap the entire pressure sensor transfer function so that i can peg it at 45psi, instead of the 60 i normally peg them at. I would set up the function for better resolution around 40psi too. This way one could decrease the integral term and increase the proportional term (opposite of typical hesitation tuning) because the proportional term will no longer react as violently because it will only see 45psi vs the common 70-90 psi spike. But then if the fuel pressure drops below 40 the proportional term will kick in with aggressive action to raise the fuel pressure.