legacycentral bbs

my FCD shorted and my car without the fcd will not start... such a pain in the ass, and to boot i was on my way to a legacy central west coast meet when it happend.

the fcd that Vrg3 made up i built, and for the last week it has been working awesome with no problems at all.... but as we were sitting in traffic my car just died.... a few seconds later i looked at my steering colum and i see white smoke.....

so i franticly ripped off the cover panel and looked down and my FCD was smoking. the capacitor had melted. and the #9 pin on the black amp. was chard black .....

so now that my car wont start i think that i probably smoked my ECU.

so does anyone have any ideas as to what might have happend to my fcd

thehookeup wrote:my FCD shorted and my car without the fcd will not start... such a pain in the ass, and to boot i was on my way to a legacy central west coast meet when it happend.

the fcd that Vrg3 made up i built, and for the last week it has been working awesome with no problems at all.... but as we were sitting in traffic my car just died.... a few seconds later i looked at my steering colum and i see white smoke.....

so i franticly ripped off the cover panel and looked down and my FCD was smoking. the capacitor had melted. and the #9 pin on the black amp. was chard black .....

so now that my car wont start i think that i probably smoked my ECU.

so does anyone have any ideas as to what might have happend to my fcd

I think you let the white smoke out...




Sorry dude. I know your pain.

I put a cheap power supply in a performance PC, my desktop - and last monday the PSU smoked, yep, same white smoke ordeal. It killed my hard drive, CPU, motherboard, a few network cards, and a gig of memory.


Shit happens huh?

Was it an electrolytic capacitor? If they're wired backwards, not rated for the voltage they're exposed to, or defective, they can leak. The leaked electrolyte can then short other connections (which is a good reason to seal the circuit in epoxy).

If the capacitor did short out anything, the power supply was probably the first to go. If the ECU is still powering up (the check engine light turns on when the ignition is turned to ON), then most likely its internal power supply for the MAF sensor is damaged; turbo ECUs won't start without a functional MAF sensor.

You can check this by measuring the voltage on the MAF power supply wire. If this is all that's damaged (and that is actually a likely scenario), you can just wire another ignition-switched +12v source to the sensor instead.

But first check fuses. In particular, look at SBF-2 underhood.

ok so every fuse has been checked, engine bay and cabin......every fuse is perfect. all in wires seem to be perfect.. giving and receiving the voltages that they are supposed to.....with the Stock ecu plugged in all the lights light up and the motor turns over. but what i noticed is the tachometer will not bounce when the engine is turning over....and i know its supposed to.....

when i plug the ecu from my N/A the tach bounces when trying to start it.......but the thing still wont start. on the N/A ecu or the turbo ecu....

with the tach not bouncing with the stock ecu, leads me to believe that the ecu is fried........

the capacitor was not an electrolyte. but it was rated for like 100 volts. like i said everything worked great until we were on our way to the legacy meet. then the capictor smoked.....

any more ideas?

thehookeup wrote:when i plug the ecu from my N/A the tach bounces when trying to start it.......but the thing still wont start. on the N/A ecu or the turbo ecu....

with the tach not bouncing with the stock ecu, leads me to believe that the ecu is fried........

the car wont start with the N/A ecu unless you switch the cam and the crank sensor wires... for some reason the turbo's are wired opposite as the N/A's (ie the cam sensor wires are in the cranks sensor wires spot and vice versa) is there anyone around there that has a t-leg that will let you borrow their computer or let you plug your computer in?

Might be a dumb question, but did you pull out the FCD and reconnect the sensor wire?

wait a sec, so i need to switch the cam sensor and the crank sensor and it will run with the n/a ecu... totally weird. never heard that before. i just heard it was plug and play. haha ill try that in the morning......

and yes i did take the fcd out. and i wired everything back to normal.

i am trying to find someone int he area who will let me plug mine in but so far no luck

I don't recall my tach needle moving when I crank my engine. The way to check if the ECU senses the engine rotation is to check if it's trying to spark by monitoring the voltage at the ignition control pins.

Jake is correct about the cam and crank sensor wires. It's not too hard to swap the pins; people have done that when doing engine swaps.

Just to be clear -- you did measure the voltage on the MAF sensor power supply pin and found it to be full battery voltage?

And you tried swapping fuses, not just inspecting them visually or with an ohmmeter?

all voltage is perfect. and just a few mins ago i swaped the crank sensor and the cam sensor pins and it ran with the NA ecu. it ran like shit. but it ran. so if i am not mistaken my turbo ecu is bad. correct?

If you made the measurements properly, then, yeah, it sounds like it.

damn, well wish me luck finding one

the ECU has a seperate power supply for the MAF? I know it does for the TPS sensor. If that's fried than it could see 0v on the signal wire and think the throttle is wide open, which would turn off the injectors under startup.


either way, it does sound like your ECU is fried.

The MAF is supplied power by the ECU, yes.

Oh, huh, I had not thought of the TPS power supply because it wasn't one of the wires tapped, but I suppose it's possible that shorting the pressure sensor's power supply could damage the TPS' power supply since one is derived from the other (or they're both derived from the same source).

Check it, thehookeup!