i'm taking the lazy way out on this one. i'll just ask rather than research to see what you all do and don't know.

1st of all, do the 4.6's even use an FPR?

if so, what would be the effect of using an adjustable aftermarket FPR on the 4.6? i was hoping that by increasing the fuel pressure that it might help w/ the pinging problems that so many of us have. by increasing the fuel pressure, i'm hoping that it would help reduce the lean condition under acceleration and give us back the power that we payed for! would the computer simply change the duty cycle to counter the increase in pressure? by having it adjustable, we could run the truck w/ higher fuel pressure in the cold to prevent pinging and then put it back to stock when the temp warms up.

gurues, i need your advice! ... or is this useless?

 

all the FPR's that i know of are for carburated engines that run an electric pump. carbs cant handle more than about 7-8 psi of fuel pressure so electric pumps that normally supply 30+ psi need to be regulated. all the FPR does is send the fuel that is not needed back to the tank through a return line. at WOT most or all of the fuel will flow to the carb since a large volume of low-pressure fuel is needed then. at less than WOT the excess volume of fuel is just sent back to the tank.

for fuel injection you need more fuel pressure so i dont think FPR's are normally used, but i could be wrong.

in the old days mechanical pumps were turned by the engine, so the amount of fuel they provided was increased with engine speed... it was simple because at higher rpms the pump would natrually provide the increased fuel flow.

 

many guys for many years have been using FPR's on modded Probe GT's. the additional fuel can work wonders w/ these cars. hopefully it can do the same on my truck and others, but i'm not sure if the systems operate the same.

 

I did a quick search within the Modular section of The Corral and it definitely appears that 4.6 guys are using adjustable regulators. I didn't see where they were using an adj. FPR to solving pinging problems, but it may be worth investigating.


If you have a '98, the info in the below thread would cause a problem if Ford was consistent in '98 with F-150's and Mustangs.

http://www.corral.net/forums/showthr...fuel+regulator

 

HI!... I'm working on this very thing on my truck right now. My "99" F-150, 5.4 does'nt come with a adjustable fuel regulator. All F-150's don't come with one. The problem on my truck is that FORD's incorperated the non adjustable fuel regulator into my fuel rail it'self. So you can do much with it or even add a aftermarket fuel regulator. What I did find was that on my "98" 5.4 crate engine, is that it has a different fuel rail set-up than my "99" 5.4. It looks almost exactly the same but FORD used a BOLT ON non adjustable fuel regulator. I'm in the process of using this fuel rail on my truck. ACCUFAB, ACCEL, VORTECH, and AEROMOTIVE all make adjustable fuel regulators that will bolt right on to this fuel rail in place of the factory one. If you want to see if you can get a actual gain by using more fuel pressure, try this. It worked for me. Find the non adjustable fuel regulator. There is a vacuum line running to it. With the vacuum line hooked up I get 33PSI at idle, 33-35PSI while cruising and 41PSI while at WOT in 3RD gear. With the vacuum line un-hooked and plugged I got 43PSI at idle, while cruising and at WOT in 3RD. You SERVICE ENGINE SOON light will come on because the computer is sensing a TOO RICH condition, but on my truck this is only at idle. We confirmed this with a scan tool. As soon as my truck goes above 1500rpm the computer starts leaning me out a bit to compensate. All I can say is HOLY *****!!!!!! My truck has had a fuel starvation problem for a few years now and this totally fixed it. I bet I knocked off at least 3-4 tenths with more fuel that I desperately needed. It's almost fun driving my truck again. The seat-of-my-pants meter tells me it pulls better now just like when I added my SUPERCHIP. I can't wait to get back to the dragstrip in another month or so. I'm adding a 90mm MAF, 80MM TB, TRUE RAM AIR, and a new custom programmed SUPERCHIP "FLIP-CHIP" to work with it al. I'm hoping to break into the 13's still N/A (naturally asperated) !!!!!!!

 

Things to consider. If you are running lean the PCM will see it at the O2 sensors. If PCM is able to richen up the mix it will and not set a code. If the PCM is unable to it will try other things like take out some timing. This is where you gain some ( key word: some) power on a stock or near stock engine. If the PCM has richened up the mix as much as it can it will take out some timing and you get robbed of power. In the case of Neal's truck the PCM was probably maxed out on pulse width and in order to keep the engine happy it was taking out timing. Now that there is more fuel pressure, less timing or none at all is being taken out. That is where Neal's power is probably comeing from. The code is being set at idle because timing is at a minimum and can not be reduced and the PCM can not shorten the pulse width any more than it has and the added fuel pressure is making the mix too rich.
I tried the same thing as Neal on my truck. I thought that it did something at 3500+rpm, but when I reconnected the vacuum line there did not seem to be any difference.

Regards

Jean Marc Chartier

 

I haven't tried first hand, but the input I have seen is similar to Neal and JMCs.

Having spent time in some of the tuner forums, it is clear that the PCM will try to compensate and adjust the mixture. As JMC said there are limits to what the PCM can deal with and done properly it can be fooled. Looks like it works in Neals case, but might not in another.

In theory the PCM will relearn back to the original fuel trim the computer was at. I have seen some debate as to how far the PCM can compensate, but several of the tuner types claim unless you are getting the idiot light warning such as Neals case, that your fuel trim is not really changing.

An easier way to go would just be using a chip to compensate for the ping. It would cost a little more but shouldn't be as hit and miss. Just my .02....

 

i should have known that Neal would be all over this 1!

thanks for the replies everyone.

i still have a couple points to make and questions to ask, so here goes...

if the check engine light comes on, is the only way to erase it by using a scan tool? i'm not very familiar w/ OBDII systems... yet.

w/ higher fuel pressure, are you sure the computer will relearn to the original specs? to my knowledge, the computer has no direct way to monitering fuel pressure. from what many of us have experienced there seems to be a glitch in the current program that doesn't acknowledge a lean condition that causes pinging and power loss. no cel is sent to the ECU and obviously the ECU doesn't compensate for the condition by adding more fuel. (i'm getting the feeling that this is going to be tough to follow) for what ever reason the ECU is not programmed to add more fuel regardless of how much the timimg is retarded and pinging is still present. i'm hoping that bc the ECU can't directly monitor fuel pressure, that by bumping it up a few psi mayy fool it into leaving the timing where it should be and still not trip a code.

maybe i'm trippin'? i dunno.

for whatever reason, i'm not big on the idea of a chip. i like my truck the way it is when it runs right(maybe half the year). i guess i'm not thrilled about throwing a couple hundred bucks at a pinging problem in the form of a chip that i might not like. i really don't feel like *****ing around w/ someone if the chip doesn't solve the problem too. i wish Ford would just reflash the damn computer to make it the way it should be. then i can drive off into the sunset and live happily ever after. for whatever idiotic reason, that's too hard for them to do. i'm sure i'll figure out what the probelm is 2 years from now and about a week before i'm about to sell it!

 

Ping is a metallic rattling sound produced by the engine during heavy acceleration when the ignition timing is too far advanced for the grade of fuel being burned. The cure is to increase octane or retard timing. Detonation is when the pressure in the combustion chamber is so high the unburned gas ignites producing two flame fronts and this increases the burning rate and the violent explosion caused by this slams the piston down. Too high a compression ratio or a low grade of gasoline is sometimes the cause. A peice of carbon or an overheated valve can also cause this. If the combustion chamber is carboned up the CR gets too high. A spec of this carbon will glow hot and set it off. To decarbonize the engine should help. Preignition is caused when a glowing bit of carbon, overheated plug, etc ignites the fuel charge before the plug fires. This explosion tries to force the piston down against the direction of rotation. The PCM is trying to control the fuel ratio. It uses the O12 sensors to know if it is rich or lean. It can add remove both fuel and timing or a combination. But there is only so much that it can do. Finding what the problem realy is and fixing it right is the only way to go. So does your engine ping, detonate or preignite?

Regards

Jean Marc Chartier

 

HI!... I finally got some pics takin of my "98" 5.4 fuel rail. This is the one that I'm going to install on my "99" 5.4. The reason is because my "99"s fuel rail does'nt have a removable non adjustable fuel regulator. It's built right into the fuel rail it'self. This one uses a bolt on non adjustable fuel regulator. This can be unbolted and removed and replaced with a aftermarket adjustable fuel regulator. Here's a few pics of the "98" 5.4 fuel rail and the AREOMOTIVE billet adjustable fuel regulator I'm going to use.

https://www.f150online.com/galleries...-793-15772.jpg
https://www.f150online.com/galleries...-793-15775.jpg
http://www.aeromotiveinc.com/pics/im...unt_ford_l.jpg

 

white elephant,

Good points and questions, here is my understanding of what is happening in your situation.

The PCM does monitor mixture using the O2 sensors. Since you aren't getting any CEL then most likely the O2 readings are within acceptable limits, but the timing is too far advanced under those conditions causing the ping.

I assume that your ping is happening under heavy throttle conditions, and most likely enough to cause the PCM to be operating in open loop mode. This is another issue of debate on Ford PCMs, some claiming the look up tables used in open loop mode will somewhat "learn" while others saying all variables are a set table. Although I am no expert, from my understanding of the function of the PCM it would be impossible for it to not somewhat learn these changes.

The other side of that argument is that the open loop settings can't change, and that fuel pressure changes will in fact change performance in open loop mode........ but cause the computer confusion when in normal closed loop mode. Neals example might support this side of the argument, otherwise the CEL wouldn't appear if the PCM was handling everything.

I am also in the same boat as you concerning chips. Though I would like to alter my shifting and a few other things, I don't feel the actual power increase justifies the cost in many cases. On my '95 I can also advance timing and have found a good setting for overall performance, even though a chip might strengthen some areas.

 

FYI From the Manual;

The Fuel System Monitor is an on-board strategy designed to monitor the fuel trim system. The fuel control system uses fuel trim tables stored in the PCM's Keep Alive Random Access Memory (RAM) to compensate for variability in fuel system components due to normal wear and aging. During closed-loop vehicle operation, the fuel trim strategy learns the corrections needed to correct a "biased" rich or lean fuel system. The correction is stored in the fuel trim tables. The fuel trim has two means of adapting; a Long Term Fuel Trim and a Short Term Fuel Trim. Long Term relies on the fuel trim tables and Short Term refers to the desired air/fuel ratio parameter "LAMBSE". Both are described in greater detail in this section under Powertrain Control Software, Fuel Trim. Input from the ECT or CHT, IAT, and MAF sensors is required to activate the fuel trim system, which in turn activates the Fuel System Monitor. Once activated, the Fuel System Monitor looks for the fuel trim tables to reach the adaptive clip and LAMBSE to exceed a calibrated limit. The Fuel System Monitor will store the appropriate DTC when a fault is detected as described below.

1. The heated oxygen sensor (HO2S) detects the presence of oxygen in the exhaust and provides the PCM with feedback indicating air/fuel ratio.

2. A correction factor is added to the fuel injector pulsewidth calculation according to the Long and Short Term Fuel Trims as needed to compensate for variations in the fuel system.

3. When deviation in the parameter LAMBSE increases, air/fuel control suffers and emissions increase. When LAMBSE exceeds a calibrated limit and the fuel trim table has clipped, the Fuel System Monitor sets a Diagnostic Trouble Code (DTC) as follows:

The DTCs associated with the monitor detecting a lean shift in fuel system operation are DTCs P0171 and P0174.

The DTCs associated with the monitor detecting a rich shift in fuel system operation are DTCs P0172 and P0175.

4. The MIL is activated after a fault is detected on two consecutive drive cycles.

 

i don't know all of the abreviations off the top of my head, but it looks as if the knock sensor is not included in the list of sensors that the PCM derives info from to make corrections in relation to the fuel trim.

i'm not a combustion expert, but i wonder if pinging can cause a unusual burn that might trick the PCM into thinking that the air fuel mixture is just peachy when in reality it isn't.

i need to do more homework on this topic before i can make any more guesses. if i can figure out how the various combustion conditions change and the result of how the sensors react, then maybe i can come up w/ a solution.

 

The knock sensor (KS) is a tuned accelerometer on the engine which converts engine vibration to an electrical signal. The PCM uses this signal to determine the presence of engine knock and to retard spark timing. The Knock sensor has nothing to do with the fuel trim. It only causes the PCM to retard timeing.

The vehicle speed sensor (VSS) (Figure 43) is a variable reluctance or Hall-effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling.

 

I am starting to thing that the VSS can cause pinging problems. If the vehicle speed is actually lower than what the sensor is inputing to the PCM, the PCM in turn may try to advance the timeing too much. The engine pings and the knock sensor sends a signal to the PCM and the timeing is retarded. Ford uses the same speedo gear for a wide range of tire sizes. If the last tire size in the given gear range is too close to the limit it may be off just enough to cause the VSS input to read too high for the actual speed and the engine gets too much spark advance and it pings.

grasping at straws here...

JMC