connell

on the way to a great hangover breakfast, i noticed the boost "guage" was only varying between 0.9 and 1.0 bar. and there was a definite lack of power.

i just checked the codes on the CC unit and got 8.7 and 15.1

8.7 doesn't seem to mean much for performance and when i checked it it had a value of 215 (if that means anything to you guys)

15.1 tho mentions limp home mode. the value on that channel was 255.

sooooo. can someone tell me what this means? how do i go about fixing this? and are these codes related to the boost values i'm seeing?

i have the bentley and am looking through it to see it gives me an answer but i though i'd ask here too.

thanks alot guys

UrS4boy

Check for boost leaks. Including MM hose and plastic cross-over tube.

connell

where does the map sensor sense from? i mean, even if there's a massive leak, wouldn't it still register a vacuum while idling? (i'm assuming it's in the intake manifold)

it supposedly had a leak repaired before i bought it, maybe it's "unrepaired" itself.....

UrS4boy

the ECU. Any leaks between the turbo will yield a boost loss. The Michelin Man hose between the cross over tube and the intercooler is famous for cracking in the valleys and only opening up under higher boost levels, i.e. it becomes a boost limiting device. The problem is the ECU had a certain air flow from the MAF sensor so it gave the injectors the appropriate duty cycle signal. If there is a boost leak, less air shows up at the intake manifold, causing the engine to a) have less boost and b) run rich (too much fuel for the actual air). The ECU gets the "rich" signal from the O2 sensor and says "This does not compute" (aka "WTF?") and puts you into limp home (to the dealer mode). Until you shut off the car and reset (reboot the computer). - Until you ask for more boost(put your pedal down) and start the process all over again.

Take your belly pan off and examine the MM hose and the plastic cross over tube. The cross over tube on the S6s also fails (splits with higher boosts).

HTH

connell

but what about the boost value in the cluster? why does it not register anything other than 0.9 or 1.0 bar? is that a symptom of limp mode? IE: the computer goes into its "wtf" loop and ignores the input from the map and therefore the instruments just say 1 bar and stops updating?

i'm going to stop by home depot motorsports this evening to make a pressure tester, hopefully it is something as basic as a boost leak as i'm sorta in between mechanics right now....

on the plus side, it's fun to be driving my Corrado again!!!!

connell

looks like the vacuum line to the ecu could be buggered up, i'll check that first

UrS4boy

1.0 bar = atmospheric pressure (no boost). The problem will be at the moisture trap, under the black plastic 2" x 4" x 16" cover on the fire wall (2 quarter sized 90 deg turn plastic "bolts"). The hose boost hose is off the moisture trap.

connell

boost is back, thanks a bunch!