experience with Apexi PFC? Runs on Stock ECU. Ran Before

[IronMonkey]

Hey guys, long story short, I put in my new engine a while back, but I believe my wiring was chewed up to cause fuel injectors to be opened even when the car is not running. Got a new wiring harness from chasebay. Hooked everything up, its not doing that anymore, it starts but dies right away. But when I try on a stock ecu, it starts and runs despite the engine currently has bigger injectors, maf, and throttle body. Im wondering if anybody has any ideas or know where I can get my apexi pfc service at? Or anybody can take a look at the board? Do you believe its the power fc? Fuel injectors or pump? Thanks in advance.

[robbie2883]

ok...well first did you initialize the pfc? so it's in it's original form on the base maps? then did you do the calculations and make adjustments in the pfc for the injectors sizes and lag? did you turn off the boost control setting on the pfc? and last but not least did you do the idle learn procedure for the pfc?

[IronMonkey]

the pfc has already been running in my car for the past 6 years and already been tuned :/

[robbie2883]

gotcha...the way it sounded was like you had just put it in. so it just started messing up when you swapped the harness? check the eccs wiring and make sure the ecu is getting proper power

[IronMonkey]

so i hardwired the fuel pump.....it wont stay running with the pfc....so Im assuming the pfc is not sending injector signal :/ anybody have a pfc for sale? lol

[robbie2883]

yes...that's it. just throw parts at it. makes sense. how much for your "bad" pfc?

[robbie2883]

yes...that's it. just throw parts at it. makes sense. how much for your "bad" pfc?

[IronMonkey]

i dont know if thats sarcasm or not...but if one ecu starts and keeps the car running, while the other does not, it is through deductive reasoning that the pfc is at fault.

[robbie2883]

not really. if the power isn't setup properly that exact thing can happen. which is why i asked if you checked the eccs wiring diagram against how the pfc should be wired. you'll need a DMM to test it all properly too. and by your own logic. if it worked until you changed the harness...then it must be the wiring.

[IronMonkey]

I guess Ill write it out. I have had my rb25 swap for about 8 years with somewhat of a questionable wiring. But it ran fine nonetheless. I recently got the car dynoed at 435 to the wheel @ 17psi. However, boost spiked to 25psi and blew the rings. It spilled oil all over the place, soaking the wiring harness. I took everything apart and cleaned them (ecu had some oil residue at the connection as well). I got the engine bay painted, put in the built motor and got everything put back together. However, something was shorting out the ecu to for injectors to be opened even when the car is not turning over or running. Theres two things that can cause that 1) wiring harness 2) ecu . Since the wiring was in question from the beginning, I got a new wiring harness from chasebay (new custom wiring). I put it on, and it does not run on the power fc. I put the stock ecu, and it runs. I have verifed the power fcs setting and tune already. I have the datalogit, so its easy to read and confirmed through the laptop. I want to see if you guys think of any other variable or know where I can get the pfc serviced!

[robbie2883]

if it was the ecu the your injectors would still be open and shorting. so i'll spell it out for you.....

CHECK THE ECCS WIRING!!! LOL i don't know how else to explain it. the stock ecu WILL run with the eccs wiring done wrong while the pfc will not. goolge paul r33 pfc and go through the troubleshooting section

you come on here...you ask for help...then reject the advise your given. i don't understand people these days

[95_240]

Yes double check the wiring. It doesn't matter if you bought a new harness. Check the wiring.

[95_240]

Also when did you purchase the harness? I am a customer that had to do some R&D for them and I may be able to help.

[Bluefire]

Does it actually run and drive on the stock ecu? or just starts and idles... Generally when the car will fire and then immediately die, its a MAF issue. In past experiences the engine will run and idle in limp mode with the stock ecu, but will have the issue your having with the PFC. You can also check to see if you maf is working in your PFC.

Turn ignition on, go to sensor check and see if the maf is actually working. If it isn't working I believe it will be highlighted black or the circle to the right will be empty and not filled

-Bluefire

[95_240]

Bluefire may be on to something. The harness was incorrectly pinned for the maf on my harness.

[IronMonkey]

Does it actually run and drive on the stock ecu? or just starts and idles... Generally when the car will fire and then immediately die, its a MAF issue. In past experiences the engine will run and idle in limp mode with the stock ecu, but will have the issue your having with the PFC. You can also check to see if you maf is working in your PFC.

Turn ignition on, go to sensor check and see if the maf is actually working. If it isn't working I believe it will be highlighted black or the circle to the right will be empty and not filled

-Bluefire

thank you...thats what i was looking for..... im sorry....the other guy telling me to look for stuff without telling me the reason behind it or some kind of theory to back it up..... dont understand people these days?

it starts and idles on the stock ecu, i havent driven it since the there are so many changes to the car to drive on the stock ecu safely. I was under the impression that if it was maf related, it would still run without hooking the maf up? But I would check the sensor on the powerfc when I get home.

edit---finally saw that you put something more productive then "just check your wiring"..... ill look into pauls website...

[95_240]

Seriously. I know more about the chasebays harness than the people who sell it. I know they had to make some changes because of what I discovered on mine. If you can tell me when it was purchased I might be able to help you narrow down your problems.

[IronMonkey]

i just recently got it.... about 1-2 months?

[95_240]

That is close to the time frame of when I reported problems so they may have fixed it. On mine the maf had the power and signal wire backwards. The cas also had the two signal wires backwards and I had to send my harness back in because the speedo was wired incorrectly and needed new wire run. Good thing about chasebays is their customer service. He stands behind his product and is willing to fix anything that is wrong.

[IronMonkey]

how did your car react to those incorrect wirings? How did you find out?

[95_240]

Well I doubt your cas wiring is bad. Mine wouldn't spark when these wires were switched. I can't remember if my car started with the maf wires backwards or not. I think it might have. The way I found out what was wrong was by testing the continuity between the eccs plug and the connector. I used the fsm to determine which wire was supposed to go where. Check and see if your pfc is reading all the sensors correctly. This is your best bet to narrow it down if it is the harness. If nothing is wrong then your pfc may be bad.

[IronMonkey]

I looked at the wiring for the maf, I went over it with people at Chasebay, it seems to be wired correctly. Do you know what kind of voltage I should be getting at the ecu for the tps and maf? I dont have the handheld anymore, what should I be looking for on the datalogit screen on my laptop?

[95_240]

I think the maf is supposed to be receiving 5v not sure on its signal and the tps should be .45 closed and 4-5 open on the signal wire. If you are testing these you would check at the sensor not the ecu. Your maf wiring could have been different from mine just because there are so many possible variants between engines and what maf sensor you are using so it could actually be correct. Someone else will have to chime in about the pfc. If they would hurry up and send my harness back I could probably be of more help. Also what maf and throttle body are you using?

[robbie2883]

sorry if my posts didn't have more info. did not mean to be short and at work, i don't have much time to post.

tps should be like stated above, maf should have a ground, 5 volt and then the signal wire will vary based on air flow. anywhere from 0-5volts. around idle it's around or above 1 volt iirc. there's also a post in the pfc faq i referred too about a fuse missing (part of the eccs circuit) that is not in the r33 from the factory, nor in the wiring diagram. stock ecu will run without it but pfc will not

you can also open up the ecu and see if there's anything fried. if so post a picture up. depending on what's fried i can probably fix it for you if you don't have anyone locally who understands circuitry.

[IronMonkey]

i saw that yesterday about the fuse, i checked but didnt see that fuse. on the datalogit, the maf is showing .005 or .010, while the tps is not showing anything. The 12 volt signal that is supposed to be at the maf is only showing 9volt I believe, I was in a hurry so didnt have a lot of time.

On the ecu pinout, theres 2 signal for the tps, one is going to the tps, one coming back?

I opened up the ecu, but couldnt find any burnt resistors, circuit, etc...

[95_240]

Like stated above you should have a 5 volt power wire going to the maf and tps.

Hook up the pfc and turn your ignition key to acc. Grab your multimeter and test the voltage both the maf and tps are getting at the sensors themselves. Next test the voltage on the signal wire on the tps. Record the voltage both closed and open. Turn everything off and repeat this process using your stock ecu. Since you can't start the car with the pfc perform this test with the stock ecu. Start the car and measure the signal voltage at the maf. If the voltages are out of spec on both ecus then test the continuity between the wires and check that the ecu is pinned correctly.

[robbie2883]

^^^what he said. the maf should only have 5 volts. not 12.

did you check the eccs wiring as wellto make sure the eccs relay and ecu are getting the proper voltages?

[jetdriver]

^^^what he said. the maf should only have 5 volts. not 12.

did you check the eccs wiring as wellto make sure the eccs relay and ecu are getting the proper voltages?

This is not correct. If you look at the wiring diagrams for any of the RB/SR/ even the KA motors, you will find a 12v feed from the ECCS relay direct to the MAF. The MAF internally drops the output signal to the ecu to 0-5.12v.

[robbie2883]

^^^what he said. the maf should only have 5 volts. not 12.

did you check the eccs wiring as wellto make sure the eccs relay and ecu are getting the proper voltages?

This is not correct. If you look at the wiring diagrams for any of the RB/SR/ even the KA motors, you will find a 12v feed from the ECCS relay direct to the MAF. The MAF internally drops the output signal to the ecu to 0-5.12v.

yepp...i was wrong. i was thinking newer nissan motors. qr, vq ect. when i posted.

[IronMonkey]

I got 9 volts going into the maf.... how much should i get at the tps?