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Discussion Starter · #1 ·
Anyone having trouble with the activation switch?????it seems like the peeps I have been talking with all seem to have trouble with them failing. I think Engcon is the only one I know that has his still working. It is way to hard to reg. by hand and the switch break downs at the worst time. I need the number to KB if someone has it out there. Any other trouble please post, I have found that most are reluctent to post bad things about KB.....not sure why, but I call it like I see it.:hammer
Chill
 

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Mine is still working but I'm looking for a source to buy more of them. I think they are made by Hobbs Corporation (i.e. a division of Honeywell). Anyone know where you can buy these low-level pressure switches at a fair price?

Thanks,

MJ
 

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I will check ! I have 2 news one. I have my BAP and BAS wired directly without the switch. I may tie them together off of one switch but for now it is wired directly with the controls knobs set to zero. Yeah I know it is a pain !

JL
 

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chillfactor said:
I have found that most are reluctent to post bad things about KB.....not sure why, but I call it like I see it.:hammer
Chill
Mine works perfectly after 8K miles...and it was tested with MJ's Autotap scan tool so it's not just speculation.

And, to address the second half of your post and your subtle dig on me, I think that the most of the flames that you are refering to are directed toward the jealous anti-KB keyboard racers. I think it's over now...I think that we've shut them up.

Believe me, if something goes bad with my KB or there's something that I don't like...I won't sugar coat it. I'm a straight shooter too.

;)
 

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Discussion Starter · #6 ·
What do you mean you have it set at 0. I have my BAP set 20 to start the car and 40 to run it smooth...............help. Hammer I was not refering to anyone, just wanted to much sure if there was a response they would let it be known. I have been trying all day to get in touch with KB and the phone is always busy....:confused:
 

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chillfactor said:
Hammer I was not refering to anyone, just wanted to much sure if there was a response they would let it be known. I have been trying all day to get in touch with KB and the phone is always busy....:confused:
In that case, my apologies, Chill. Everyone refers to me with the :hammer icon, that's why I thought you were smacking me around.

I think that everyone deals with those busy signals with KB. What I do is just keep alternating the tech and sales line over and over and I can usually get through within a few minutes.
 

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chillfactor said:
What do you mean you have it set at 0. I have my BAP set 20 to start the car and 40 to run it smooth...............help.
Is yours connected thru the 3psi switch or directly ? I can start the car with the BAP maxed but since it is wired on I usually have it set to zero.

JL
 

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Discussion Starter · #9 ·
I guess I don't really understand the BAP. Mine is wired direct with out the activation switch, so what I am thinking is that it is always on making my fuel pumps work over time and when I have it turned down low I may not be getting enough fuel....... So as you can tell I am not sure how it works without the auto switch. Someone that has theirs hooked up this way please let me know how this system works.
 

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Chill,

Mine is wired directly. With the knob set to zero there is no increase of voltage and the pumps operate as stock. When you increase the knob it increases the voltage ( amplifies ) and the pumps operate at a higher LPH rate there by reducing the Duty cycle %. MJCHIP datalogged Hammer's car in a complete thread and I also datalogged my car to show the BAP usage. You won't see a Fuel PSI increase just a Fuel Volume increase. The only way I have found the actual BAP funtioning was with an OBD II scanning the Pump Duty cycle %.

How much boost are you running at WOT ? I was maxing the duty cycle on my pumps at around 4700 rpm with the BAP off and my Fuel PSI would start to fall. This was with 19-20lbs boost. I run mine at 20% for street use and Maxed at the track. With it Maxed I never recorded more than 88% duty cycle on the pumps to 6300 rpm. Can you hear the pumps increase in whine with key on and car off ?

JL
 

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Discussion Starter · #11 ·
I will check in the morning, but that makes alot of sence now. Why waste the fuel if you don't need to. I am running 17 lbs of boost @ over 600 RWHP, so do you think I should run at 20 or higher for daily driving???? I have found that wide open is great for WOT, so at least I have been going in the right direction.:blob
 

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Well most guys with BAPs are wired thru the pressure switch (3 psi I think...) when 3 psi is hit the switch activates an the BAP is running at whatever the knob is set at. As soon as the throttle is let up and vacuum takes over and the boost bypass bleeds off excess boost (very quickly) less than 3 psi the switch deactivates the circuit and no more BAP. I don't drive my Cobra daily so I am not as concerned having 20% or 30% for daily driving. If you are not into the boost cruising 80mph you would not need it anyway.

Compare it to larger pumps if installed. The larger pumps would be pumping more volume at a given RPM so if you set the BAP to 20% most of the time, I don't think you are wasting any fuel just adding Volume behind the Fuel PSI. The Fuel transducer is going to keep the same pressure accross the injector until the pumps max out with the BAP on or off. Someone (MJChip) chime in here if I have mis-spoke the returnless system operation. Chill do you know how much fuel PSI you are running at the upper end and how much boost are you running ?

Thanks,

JL
 

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Discussion Starter · #13 ·
When the switch was operating it was some where around 90 and now that I am doing it by hand around 70 I think, but this would not make sense the fuel pressure has nothing to do with the BAP just volume...............OK back to being confused??????:confused:
 

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Sorry to confuse ! Its has everything to do with Fuel PSI being stable. To maintain the given Pressure you need to spin the pumps faster than the supplied factory voltage of 13.7 while running. THe BAP gives you the volume to maintain the PSI at the higher power levels. On the returnless system the BAP usually won't raise the Fuel PSI but the push behind it there by maintaining the given Fuel PSI that the PCM deems necessary. Some where around 90 meaning your Fuel PSI ? That sounds high. Mine holds a constant 58-64 psi with the KB chip and BAP turned up. With BAP off it holds 58-64 until Pumps Duty cycle peak at around 5000 rpm.

Email MJCHIP maybe he can explain it better !
 

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1. Delta_P (difference between pressure at pump inlet & outlet) and flow rate are inversely proportional. At a given fuel pump duty-cycle (or drive voltage) a fuel pump can pump X gph of fuel into Y output pressure (given atmospheric inlet pressure). If you increase Y, X will decrease and vica-versa.

2. The PCM strategy is to keep a fixed differential pressure across the fuel injectors so that it *knows* what the injector flow rate is and therefore what duty-cycle to apply to the injectors to get a desired amount of fuel. The FRP sensor is referenced to lower manifold pressure/vacuum so that as boost increases, the fuel rail pressure increases linearly. For example, at 0psi of boost pressure, and a desired fuel injector delta_p of 40psi, the fuel pump will be pumping into a head pressure of 40psi. Now, make 20 psi of boost and in order to keep the rail pressure 40psi above lower manifold pressure, the fuel pump will see 60psi at it's output. Since the output pressure has gone up by 50%, the total flow capability of the pump will drop by roughly 18.5%.

3. In order to get more flow from the stock injectors, one can increase the Delta_P across them. For example, let's say at 20psi of boost on the stock fuel injectors we determine that we need to run them at 70psi in order to get enough flow from them. This means that the fuel pump output pressure will be 90psi. The total flow capability of the pump will drop by 27.5% (as compared to the stock 40psi). So, there is always a trade off between injector flow/pressure and pump flow/pressure. Now, how can we get more injector flow without losing fuel pump flow capacity? Enter the Boost-a-pump.....

The Boost-a-pump effectively increases the total available drive voltage to the fuel pump when the manifold pressure exceeds 3psi (pressure switch activated). By overdriving the fuel pump, we get extra flow capacity at a fixed pressure at the expense of more heat and possibly shorter operating life. Now, if the goal is to raise the PCM's target fuel pressure as well as flow capacity a Boost-a-pump MUST be used with a chip (or eFPC). Why? Two reasons:

First, the PCM uses what it thinks is the supply voltage to the pump (battery voltage), the pump flow characteristics (at that specified voltage), and the feedback from the FRP sensor to maintain a fixed fuel pressure. If you turn up the power supply voltage to the fuel pump without telling the PCM, you may alter the dynamics of the closed-loop fuel pressure control strategy (not to be mistake for the closed-loop air/fuel control strategy) There very well may be driveability issues associated with this as the fuel pressure will have a lot of overshoot/undershoot (error) and it may be difficult for the PCM to control pressure in a transient fashion and consequently AIR/FUEL when the BAP is active!

Second and even more important, if the PCMs target fuel pressure at WOT is not increased, the PCM will cut the pump duty-cycle exactly the amount to negate the BAP's increase in rail voltage.

For example, if you were to measure the rail pressure making 17psi of boost it would read 57psi (approx.) given the PCMs target of 40psi injector_delta_p. Now, if you turn up the BAP to max (50%) without giving the PCM a new target, it will cut the FPDM duty cycle by 50% in order to maintain the same pressure. So, the only change that will occur is screwing with the dynamics of the pressure control loop.

A number of people have asked us what the difference between the BAP and our eFPC is so I thought that I'd add this:

4. Our product, the Afterburner-eFPC works in conjunction with the PCM in order to raise or lower fuel pressure in 400rpm increments at WOT. This system intercepts the FRP sensor signal (as well as the TPS and RPM signals) and modifies it in order to force the *PCM* to alter pressure. Although this allows the user to increase Injector Delta_P, it CAN NOT increase the total flow capacity of the fuel pump. The eFPC allows one to precisely raise or lower injector pressure within the PCM's closed-loop fuel pressure control loop. The PCM reacts to the eFPC's input by changing fuel pump pressure by altering the duty cycle to it via the FPDM. However, at full duty-cycle (100%) the PCM can only apply battery voltage to the pump so the flow rate is limited. This is the fundamental difference between the eFPC and the BAP.

The BAP increases the power supply to the pump so it effectively allows the PCM to overdrive the pump to get more flow at any given pressure. One really cool product would be an integration of the BAP and eFPC......maybe I should call Jim Bell about this?

5. After a ton of work investigating the '03's fuel system, I have found that one must be VERY CAREFUL when messing with fuel pressure as the control loop in the PCM is *SLOW* and unless the dynamics are properly tuned, there will be driveability issues when making large changes in fuel demand (i.e. between shifts at WOT, etc.)

There's more to it but this is a basic overview, FWIW.

MJ

P.S. This was taken from one of my earlier postings. I am currently running a BAP on our '03 Cobra and it is working flawlessly. I started out running the BAP all the time (no hobbs switch) but had startup problems. So, I added in the pressure switch and have experienced NO driveability problems due to the discontinuity caused by the switching in/out of the BAP.
 

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Shadowgray03 said:
Simply awesome explanation MJ!
Thanks. Since I've learned a lot since I wrote that, I had to make some edits. It's a constant learning process.....

On a related note, imagine what we could do if we had the knowledge of the powertrain control strategies that the design engineers/calibration engineers do? Having to reverse engineer them takes a lot of time and leaves a lot of room for error.

MJ
 

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mjchip said:
Thanks. Since I've learned a lot since I wrote that, I had to make some edits. It's a constant learning process.....

On a related note, imagine what we could do if we had the knowledge of the powertrain control strategies that the design engineers/calibration engineers do? Having to reverse engineer them takes a lot of time and leaves a lot of room for error.

MJ
Yea, its frustrating to say the least. Winter is setting in fast here in the north and hopefully I can save up some $$ to upgrade the fuel system and we will have more time to get things worked out tune wise. I have dealt with drivability issues first hand with some of my tunes and have wasted a lot of time and money trying to get a decent tune. My diablo chip is a tad lean down low but aside from that has awesome drivability. Once I get chip back Im going to start doing some data logging, hopefully get one more day in at the track end of the month. Is there any special logging you would like to see from my setup? (KB, 17psi, stock injectors, BAP installed but tuned to run on normal fuel PSI).
 

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Shadowgray03 said:
Yea, its frustrating to say the least. Winter is setting in fast here in the north and hopefully I can save up some $$ to upgrade the fuel system and we will have more time to get things worked out tune wise. I have dealt with drivability issues first hand with some of my tunes and have wasted a lot of time and money trying to get a decent tune. My diablo chip is a tad lean down low but aside from that has awesome drivability. Once I get chip back Im going to start doing some data logging, hopefully get one more day in at the track end of the month. Is there any special logging you would like to see from my setup? (KB, 17psi, stock injectors, BAP installed but tuned to run on normal fuel PSI).
Unfortunately, I'm in the same boat that you are. I've recently received three Diablo reburns all of which were screwed up in one way or another. The first one wouldn't even allow the car to start, had "--------" in the odometer. I think it may have been a PATS problem but I'm not sure. The second one (from a different tuner) was set up for stock injectors even though I clearly requested a tune for 50lb/hr injectors. The third one I'm told was done by Patrick himself and with the chip installed the car would not idle and just poured raw gas out of the tailpipes. This remote chip burning crap is really getting old fast.

I'm currently running 17psi of boost and a 75hp dry shot with the Eaton using 50lb/hr injectors and our own piggyback tuners and a BAP and NO chip. The air/fuel is perfect but I'm missing out on serious torque due to the stock timing curve. Also, I'm running into the PCMs predictive torque limits when I spray the 75shot. I would also like to have my fans come on earlier. Hence the reasons for even trying to get a chip.

I'm seriously considering developing my own PCM flash programmer/tuning software......it would be a huge task but boy would it be worth it.

MJ
 

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mjchip said:
I'm seriously considering developing my own PCM flash programmer/tuning software......it would be a huge task but boy would it be worth it.

MJ
I hear ya, there are a couple apps out there such as PCM explorer which will allow you access to everything, it just doesnt have all the data locations mapped for the 03 cobra.

P.S. Check your PM's
 
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