Big Problems With Kenne Bell Fuel System and FRPP 80lb Injectors

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JESUS use the 36's for now. When you get a bigger blower throw them back on...its not that hard of a swap man lol.

The 36s won't be able to support the hp im looking to make right now without upping the fuel pressure, which would require me to buy an adjustable fuel pressure regulator and do even more extensive tuning.

I would like to keep the fuel pressure at 39 psi. Increasing fuel pressure reduces the fuel pump flow rate.

I am tossing around the idea of getting some 60s for now as they will support enough hp for this blower and keeping the 80s to use if I upgrade the blower.
 
The FRPP values are correct. I've tested them in a '98 Cobra, which has the same injector calibration values as yours. Naturally, I've also tested them in many other newer vehicles, and the values are spot on.

If you will read my other thread here:

Ford Injector Calibration Data & Tuning Info - HP Tuners Bulletin Board

You will see where I wrote this concerning the inputting the values from FRPP's data into SCT's software:

Also, some of the data is listed differently between Ford Racing's and HPT's (and SCT's), therefore I am going to give you an example of how to input the data...

Basically, what this means is that some of the data doesn't just copy/paste. I made mention of that here:

What fuel pressure you guys seeing? - Page 4 - ModularFords.com

I'm almost positive you're inputing something wrong. If you're using SCT Advantage 3.x, please use this value file I created for the Siemens (aka FRPP) 80# injectors located at the link below:

What fuel pressure you guys seeing? - Page 5 - ModularFords.com
(you may be able to click here to download it directly: http://www.modularfords.com/forums/attachment.php?attachmentid=64236&d=1253309493 )

If you're using Advantage 2.9, then it won't work, so email me your file to [email protected], and I will input the correct values for you (if you're using SCT or DiabloSport).
 
I loaded your value file for the 80lb injectors and compared it to what I was using before for injector values. Advantage showed no differences when I used the compare tunes function. Could there be something else?

Injectors are not flow matched, could that be the problem? The maf transfer function isn't off, or at least not by much. I can run the car exactly as it is now except without the 80s and with 24s instead and a tune for the 24s and it runs fine. I can run the 24s with the stock maf transfer function, as I do with the 80s, and it runs fine as well, just not with the 80s. I'm thinking I've got some bad injectors. Nothing else makes sense at this point.

It's a 90mm LMAF sensor mounted in the fenderwell just aft of the filter. It's a JLT CAI. Ther are no 90 degree angles or any abrupt features like that in the filter.

How can I tell if I have bad injectors?
 
Looking for error in calculations

I am working through your calculations. I believe that some of the units of measure are messed up. I think there is a discrepancy between pounds per minute, pounds per second, and pounds per pulse. However, I do not have it all worked out to a point were I am willing to post.

It would help me cross check my numbers (they do not agree with yours) if I under stood the relationship between pulse width and fuel mass. This is heavy stuff that is pushing the limits of my math skills. Again, I want to double-double check before posting.:thinking:

I also found this on the Ford Racing site. Note the discussion about the small pulse width. Perhaps this does not apply in this situation as the reported condition is rich.


>>
PROPERLY SELECTING ELECTRONIC FUEL INJECTION COMPONENTS(continued...)

So, technically, the engine only needs a 19 lb/hr fuel injector to support 300 hp, but this will require that the injector is at nearly a 100% duty cycle in order to achieve this horsepower level. Duty cycle refers to how long the injector needs to be open (flowing fuel) in order to supply the required amount of fuel. If the injector needs a 100% duty cycle at a particular engine speed and load to inject enough fuel, that means it is open all the time. Under most conditions, fuel is injected when the intake valves are closed, which helps with fuel atomization and efficiency. If the injectors need to be on 100% of the time to supply enough fuel, this means that some fuel is being injected while the intake valves are open. Depending on the overlap of the cam in the engine, some of this unburned fuel can be blown right past the exhaust valve, or be poorly atomized, which makes for a less efficient combustion process. Perhaps more importantly, operating a fuel injector between roughly 85% and 99% duty cycle does not give the injector sufficient time to close before it is commanded to open again. This can cause extreme variability in the amount of fuel actually injected, which can sometimes result in a rich condition. Similar issues exist at the low end of the flow region at extremely low duty cycles, but this is highly dependent on the type and flow rate of each model of injector. In this case the injector does not have enough time to fully open before it is commanded to close again, which causes extreme variability that can result in a lean condition. For these reasons, we generally recommended selecting an injector with a flow rate sufficiently high that it will not be required to exceed an 85% duty cycle. So to figure out what size fuel injector will result in an 85% duty cycle, divide the original result by 0.85: 18.75 lb/hr/0.85 = 22 .1 lb/hr requirement.
 
I am working through your calculations. I believe that some of the units of measure are messed up. I think there is a discrepancy between pounds per minute, pounds per second, and pounds per pulse. However, I do not have it all worked out to a point were I am willing to post.

It would help me cross check my numbers (they do not agree with yours) if I under stood the relationship between pulse width and fuel mass. This is heavy stuff that is pushing the limits of my math skills. Again, I want to double-double check before posting.:thinking:

I also found this on the Ford Racing site. Note the discussion about the small pulse width. Perhaps this does not apply in this situation as the reported condition is rich.


>>
PROPERLY SELECTING ELECTRONIC FUEL INJECTION COMPONENTS(continued...)

So, technically, the engine only needs a 19 lb/hr fuel injector to support 300 hp, but this will require that the injector is at nearly a 100% duty cycle in order to achieve this horsepower level. Duty cycle refers to how long the injector needs to be open (flowing fuel) in order to supply the required amount of fuel. If the injector needs a 100% duty cycle at a particular engine speed and load to inject enough fuel, that means it is open all the time. Under most conditions, fuel is injected when the intake valves are closed, which helps with fuel atomization and efficiency. If the injectors need to be on 100% of the time to supply enough fuel, this means that some fuel is being injected while the intake valves are open. Depending on the overlap of the cam in the engine, some of this unburned fuel can be blown right past the exhaust valve, or be poorly atomized, which makes for a less efficient combustion process. Perhaps more importantly, operating a fuel injector between roughly 85% and 99% duty cycle does not give the injector sufficient time to close before it is commanded to open again. This can cause extreme variability in the amount of fuel actually injected, which can sometimes result in a rich condition. Similar issues exist at the low end of the flow region at extremely low duty cycles, but this is highly dependent on the type and flow rate of each model of injector. In this case the injector does not have enough time to fully open before it is commanded to close again, which causes extreme variability that can result in a lean condition. For these reasons, we generally recommended selecting an injector with a flow rate sufficiently high that it will not be required to exceed an 85% duty cycle. So to figure out what size fuel injector will result in an 85% duty cycle, divide the original result by 0.85: 18.75 lb/hr/0.85 = 22 .1 lb/hr requirement.


The pulse width is related to the fuel mass by the "slope" of the injector. This slope is a linear function that correlates fuel mass requirements to pulse widths. The pulse width for a given fuel mass = fuel mass required divided by the slope. The slope units are given in mass of fuel per time of pulse width. Most injectors are modeled with two slopes and a specific fuel mass per injection to switch from one slope to the other. The “high slope” models the injector when it is opening for long enough that it closely and linearly relates to its static flow rating. The “low slope” models what happens to the injector when it is opening for such a short amount of time that it spends a lot of that time actually opening and closing, so the flow rate no longer linearly relates to its static flow rate. This is an approximation of reality and should get you close enough to run well. The minimum pulse width for an injector is when the two slope approximation is no longer close enough. The injector should not be operated below that threshold as its flow rate becomes unpredictable.
 
On a side note... I ordered and installed some flow matched 60lb FRPP injectors and they seem to be working much better, but a bit rich when I'm opperating them in the low slope range. Some minor tweeking of the injector slopes and MAF curve should do the trick.

If all things work out with these 60s, I'll send the 80s off to get flow tested to check that they are or are not defective. If they aren't defective, then I will have to conclude that either the ford values are off, or my ECU is somehow unable to operate them properly with those values.

I'll keep you all updated on the progress.

Thanks to all who have been working through this with me.
 
Rickyll7

You asked for help to review the numbers. In order to cross check work, I needed to know the mass of fuel for a given pulse width and pressure. Instead responded with a lot of techno speak. While I can be accused of the same crime, your response provided no real information.

It is clear that you have a reasonable grasp of the techno's of the process. However, you did ask for help in cross checking your work (I assumed that you wanted PROOF of why your calculations did not work). Instead, a poke in the eye. :stick:

Not really wanted to start a flame thread, I am going to drop out and let you work through this by yourself.:Teh-Win: While I speak only for myself, IMO 80#'s are awful big to expect stock like performance.
 
Rickyll7

You asked for help to review the numbers. In order to cross check work, I needed to know the mass of fuel for a given pulse width and pressure. Instead responded with a lot of techno speak. While I can be accused of the same crime, your response provided no real information.

It is clear that you have a reasonable grasp of the techno's of the process. However, you did ask for help in cross checking your work (I assumed that you wanted PROOF of why your calculations did not work). Instead, a poke in the eye. :stick:

Not really wanted to start a flame thread, I am going to drop out and you work through this by yourself.:Teh-Win: While I speak only for myself, 80#'s are awful big to expect stock like performance.

Sorry for the overly technical response, I was only trying to help and I guess I over did it. In re-reading my response, I realized that I left out what you were asking for. Sorry about that.

The low slope I was writing about is what correlates the fuel mass to the injector pulse width.

The FRPP low slope value for the FRPP 80lb injectors is 0.028183 lb fuel/second pulse width.

So the pulse width required for any amount of fuel would be that amount of fuel divided by the slope (0.028183).

Thanks again for the help, it's much appreciated.
 
I sent you my tune. Are there any values I'm leaving out? I loaded all the values from the ford data sheet, which is the same as the SCT value file for those injectors and I divided the crank fuel by 4 since the injector values didnt address those and the i divided the minimum pulse width by 2 so that the injectors will fire during cranking. How can I test an injector to see if it's stuck open?

Just wondering if you ever got this figured out? This info could really help me with what I am trying to do with my TT mustang. I am trying to tune 160 lb injectors on E85 and having a lot of trouble getting it to even Idle.

Before anyone says anything, yes I know it can be done as there are several guys that have done it.

Ricky- You mentioned that you divided the pulse width by 2 so the injectors will fire. I was told by James at RWTD on the HP Tuners board to never ever change the minimum pusle widths or the slopes except for scaling the slopes, breakpoint, and engine displacement but leaving min pw alone. I am now wondering if this value is too large and is preventing the car from firing? I can get it to run if I put it to the floor but it is at the minimum on the wideband with an AFR of 10. Very very frustrating.

On another note, I had the FRPP 80s before this but they were beyond maxed so I went to the 160s. My car is an 01 and I am tuning with SCT and it ran great. I just used the value file for the 80s from SCT, the BA2800 values, and a blown 2 valve with PI heads value file and it ran great.

Please let me know what you think.
 
Just wondering if you ever got this figured out? This info could really help me with what I am trying to do with my TT mustang. I am trying to tune 160 lb injectors on E85 and having a lot of trouble getting it to even Idle.

Before anyone says anything, yes I know it can be done as there are several guys that have done it.

Ricky- You mentioned that you divided the pulse width by 2 so the injectors will fire. I was told by James at RWTD on the HP Tuners board to never ever change the minimum pusle widths or the slopes except for scaling the slopes, breakpoint, and engine displacement but leaving min pw alone. I am now wondering if this value is too large and is preventing the car from firing? I can get it to run if I put it to the floor but it is at the minimum on the wideband with an AFR of 10. Very very frustrating.

On another note, I had the FRPP 80s before this but they were beyond maxed so I went to the 160s. My car is an 01 and I am tuning with SCT and it ran great. I just used the value file for the 80s from SCT, the BA2800 values, and a blown 2 valve with PI heads value file and it ran great.

Please let me know what you think.

I installed some 60 lb frpp injectors and things are running great right now, but only after discovering that the KB bypass valve design was causing some serious low load issues and dealing with that. I also had too do some slight maf curve scaling due to a different CAI. KB claims that its only an issue with non-stock cams, heads, etc. -- Which makes sense, because most people dont seem to be having the trouble.

Anyway, i dont know how much of my problems were from the 80s because i did need to do some significant maf curve scaling with the CAI (around 20% at low speeds and low loads) and disable the bypass valve.

have you changed anything else besides the injectors? what is the proper A/F ratio supposed to be for E85? perhaps the flow characteristics of E85 through the injectors are a bit different for E85 than gasoline.
 
Stoich for E85 is 9.7:1 but on a wideband it reads the same as gasoline. I don't think the flow is the issue I just think it's in the tuning.

Everything is different on my car, all forged short block, ported heads and intake/throttle body. BA2800 MAF.
 
I don't think I really have any advice for you. I've never worked with that maf, those injectors, or e85. I'm by no means an expert. I've only ever tuned my own car and only with two different setups.