capnChunk

Hey - I was wondering if anyone has had issues after they installed their FCD. My boost gauge is T'd into the line that runs up to the boost sensor, and now I'll be damned if it's running right. Before the FCD I'd get it up to 8 lbs then back off because of fuel cut - now it's like I can floor it and only have it read out like 6 lbs. Is the computer now fooled enough to be running the car really rich or something that is preventing more boost? If it helps, everything kinda went insane all at once. My Apexi turbo timer used to say 20+ A/F when I would just chill at idle, but now it sticks around 13.7. I guess I can't complain too much, I'm not hitting fuel cut anymore...

SureShot

I assume the boost gauge hose is T'd in between the intake & the orifice pill.
Even if was down stream of the pill, it should still show a true reading - just delayed a second.

Is the weather warmer since you were getting the higher boost?

You might try a different source for the boost gauge.
I'm thinking there might be a leak in the pressure sensor circuit.

My favorite is the nipple that went to the thermo valve, that controlled the old double throttle.
It's the bottom one of three facing the firewall.

Henrik

An external FCD works by clamping the output of the boost sensor. This limits the max value that is seen by the ECU AND the in dash gauge (they share the same wire). Your FCD is apparently set at around 6psi (kinda low).

If your running and FCD always have an mechanical boost gauge as well, otherwise you don't know what boost your really running. If you want your in dash gauge to not be affected by the FCD check out the Rtek7 chip (www.pocketlogger.com)

-Henrik

capnChunk

I have an external boostgauge as well - so I get a real boost idea. I understand that the Apexi built in A/F gauge isn't exactly what I'd like to rely on for saying something is wrong - but any idea why the numbers on it would change after installing an FCD? I gave the car a solid push on the highway - and following what the external boost gauge said, I had 5 psi boost in 1 and 2 and then finally managed to get up into 8 and 9 in 3rd and didn't really try for 4th as a semi was coming up quick. I used the proceedure from FC3S.org and had an electrical engineering prof help me out to make sure I didn't screw it up too bad. We even put it on a variable voltage source and tested it from 0v to 5v and it never went above 3.7 volts on the testbed.