Post FPDM Boost A Pump Install

[EvilTwins]

Can I please get a wiring diagram for a post-FPDM installed BAP with relay and wire upgrade? This is what my car has but something is wrong because the BAP is staying on...

Would changing to pre-FPDM require a retune? Would there be any chance of frying the FPDM? I'm running a modified FPDM and GT pumps with the BAP.

 

[redfiresvtsnake]

I would def install the BAP PRE-fpdm. If you install it post fpdm the pcm no longer has full control over the pumps and can cause some tuning issues. There is no disadvantage of installing pre-fpdm. You won't fry the bap this way. I have mine wired pre-fpdm and running full time as I don't use the boost switch that comes with the kit. I set mine to 40% and it's been there for the past 54k miles with no issues. OH and there is not any tuning required if you move the bap to a pre-fpdm configuration.

 

[EvilTwins]

OK but don't forget the BAP is already installed, and the car runs great the way it is (no tuning issues). The only issue I have is that the BAP stays on and runs down the battery. I am hesitant to switch to pre-FPDM because it will definitely mess with my FPDC a bit.

And no one is afraid that running the amplified voltage from the BAP through the FPDM could damage it? With my hp the fuel pumps are definitely doing some work..

 

[jm@ReischePerf]

I can't really understand how your BAP is staying on all the time though whether it's wired pre or post because it's power should come from the computer either triggered through a relay or wired directly.

 

[EvilTwins]

Yeah I don't really understand what's happening. The brown/pink wire from the FPDM connector is run to the relay to close it, and when you check this source with a voltmeter it goes 12V with ignition on and goes dead with ignition off. The weird thing that's happening is when you turn off the ignition and check the voltage on that source to the relay it reads like 14V, and that voltage changes with the dial setting on the BAP (obviously being amplified through the BAP). If I pull the 30A BAP feed fuse the relay will open again after a second or so, and when I put the fuse back in the relay stays open...

Can someone figure out what's going on?

 

[EvilTwins]

Just wanted to reiterate:

The feed source that's turning on and off the relay appears to be fine. Like I thought about just setting up a switch to turn the BAP on and off but I don't even think it would work, somehow the BAP output is making it back to the signal source??????

 

[black03]

Can someone figure out what's going on?

Install the BAP before the FPDM, make sure your wiring is correct and let us know what happens then.

Jared

 

[EvilTwins]

I'm definitely reluctant to change a working setup, I just wish I could figure out why the damn thing is staying on!! I definitely can't hurt my FPDM and I know my car is tuned very well with it installed this way, so I dont see the reason why people say installing post-FPDM is such a no-no? I continually read it may cause tuning issues, but that just hasn't been an issue for me. I really want to see if I can find the reason why it's staying on before I switch to pre-FPDM and possibly cause other issues. I know there has to be some people out there running post-FPDM with the relay and wire upgrade without this issue....

Oh by the way Jared my oil pan got here friday instead on monday! Damn that was quick!

 

[AMB]

EvilTwins

Who did the BAP/Wiring install ?? What is the relay pin number that you have each wire going to and where is it going. If we know how it wired up, we can tell if it is installed correct !!! :shrug:

 

[EvilTwins]

This is how I have it wired at the moment: (I re-did the wiring because whoever installed it originally did not solder)

Relay Pin #87 - 8AWG Red 12V Fused Power Wire from Car Battery
Relay Pin #30 - 30A Fused Red Wire Feed to BAP
Relay Pin #86 - Brown/Pink Wire going TO the FPDM Connector Plug
Relay Pin #85 - Bolted to FPDM Ground and common with BAP Black Ground

BAP Non-Fused Red Wire to Brown/Pink Wire in the Harness going TO the Pumps

Pin 30 and 87 can be swapped interchangibly with the same results. From everything I've read this is wired up correctly?

 

[AMB]

EvilTwin

I beleive you have it installed wrong !! If you install The BAP after the FPDM, you have to install the wiring upgrade to the input of the FPDM and then install the BAP to the output of the FPDM. You are trying to install BOTH to the output of the FPDM, that is why is doing what it is doing. If you still want to install the BAP to the output of the FPDM, you will need to change the wiring to:

Relay pin #87-is OK
Relay pin #30- goes to the DG/YE Wire to the FPDM Conector Plug
Relay pin #86-goes to the DG/YE Wire from the stock wiring harness
Relay pin #85-is OK

The BAP red fused input wire goes to the Brown/Pink Wire going TO the FPDM Connector Plug.

The BAP red output wire goes to the Brown/Pink Wire in the Harness going TO the Pumps.

I would recomend to change the BAP to pre FPDM, sens you have change it anyway. If you do, hears how:

Relay pin #87-is OK
Relay pin #30-goes to the Red Fused BAP input wire
Relay pin #86-goes to the DG/YE Wire from the stock wiring harness
Relay pin #85-is OK

The BAP Red output Wire goes to the DG/YE Wire to the FPDM Conector Plug
Reconnect the BR/PK Wires together.

 

[EvilTwins]

Cool man that actually does make a lot more sense. I will rewire it so it is still post-FPDM and see how it works. Is there a chance it will change anything with the tune?

Thanks!

 

[AMB]

EvilTwins

Your tune WON'T change, even if you install the BAP before, OR after the FPDM. The computer controles the pumps better with the BAP before the FPDM. All the BIG tuners say to install the BAP before the FPDM. :thumbsup:

 

[redfiresvtsnake]

Your tune WON'T change, even if you install the BAP before, OR after the FPDM. The computer controles the pumps better with the BAP before the FPDM. All the BIG tuners say to install the BAP before the FPDM. :thumbsup:

+1, and it makes driveability better because of having more control over the pumps and fuel pump duty cycle. My car ran noticeably smoother after rewiring it pre-fpdm.

 

[jm@ReischePerf]

I agree...

Another reason to install pre-FPDM that is more technical: Power tends to travel more easily at higher voltages. If you install post FPDM the BAP has to pull more current (amps) through it which generates heat and could overload the FPDM sooner because the BAP steps up the voltage and will use additional current to do this. When the BAP is pre FPDM the voltage is higher but amperage will be less and this is easier for the FPDM to deal with. Pumps are going to make the same output at any given voltage (no matter how it gets there) so I can't see how the tune could be affected either.

 

[IronTerp]

Nice diagnostic AMB!!!

And Evil, the post-FPDM install on Terminators died a hard death about 4 years ago. No reason to reiterate what others have said above, but the FPDM does an EXCLLENT job of controlling fuel pump output and when you wire post-FPDM, you're putting that control in the hands of the BAP. Not optimal.

 

[EvilTwins]

I guess I'll bite the bullet and install it pre-FPDM... One of things that really creeps me out about installing the BAP pre-FPDM is tying it in to that puny factory wiring!

I mean the BAP itself has like what, 10awg wire and a 30A fuse on the feed? It just seems like if you even ran 30A through the factory wiring the wiring itself would fry.... It just seems rather sketchy but I guess lots of people do it. I liked that with my wiring now the discharge of the BAP went right to the 2 large brown/pink wires going to the pumps.

God damn I don't want to re-do all that! @#%$##@&*#$!~!1!!!!

On an unrelated note at least I finally got the transmission out of the car. Man changing out the oil pan is such a huge PITA.... At least that Canton is gonna look nice

 

[EvilTwins]

Can someone tell me why my signature only shows up half the time on this site? haha so weird..

 

[redfiresvtsnake]

Can someone tell me why my signature only shows up half the time on this site? haha so weird..

It only shows on your first post in every thread. All other posts in after that same thread don't show your sig.

 

[jm@ReischePerf]

It just seems like if you even ran 30A through the factory wiring the wiring itself would fry....

Don't sweat it man, it's ok to run a lot of current through a smaller wire on a short run. It's the longer runs where the small wires start to have problems and resist current flow. Besides the output of the BAP will never see 30A because it will increase voltage while lowering amperage.