Hey all you smart guys out there... I picked up my 01 tt yesterday and was in the passenger seat while a race buddy of mine mashed the throttle. .9 bar thruout the 1st and 2nd gear pulls. Every time he came off throttle, the car would flash 1.3-1.4. So that's why I was getting codes of the overboost(see earlier thread). Still haven't heard from the PO about his potential mods, but everything appears untouched.

What's stuck? Diverters(BOV?)? Stuff I have NO idea about? My turbocharged Porsche knowledge, however small it may be, is with dated stuff: 930s and a 951.

I'm putting pre-cat O2 sensors in today as it threw a code for those.

Thanks guys. (Didn't find anything on initial search.)

 

You are seeing a boost spike when the throttle snaps shut.
I would really find out all of the mods and who's tune you are running before you hammer the car to much.

You had no o2 sensors in? Do you have cats, or are they straight pipes or gutted?

 

in most modded cars its normal to see the boost rise right after you let of the throttle like that, i forget how todd explained it to me but basicly its due to the location of the boost sensor.

 

tvurt, Yep, we agree. O2 sensors in, but getting the pre-cat O2 sensor "heating before cat" code for both banks. Just means it's getting old/near failure. Stock exhaust w/cats. Def no hammering for the time being.

unv, thanks for the info. Man I really need to hear from the PO.

 

I've always seen this to mean the connection to the O2 sensor is open, and the DME sees no cat preheat current at start up. The reason you do not see an o2 sensor code is on start up the DME ignores the o2s until it is past warm up- however it immediately checks the o2 sensor heater circuit.

If an o2 sensor is unplugged, this is usually the code you get, FYI.

(Not directly 996TT experience, btw- so take it for what it is worth.)

A

 

ard, Thanks. Then I may waste part of the afternoon as I'm gonna put the new ones in. Both are plugged in. I checked.

 

Does that car have a BOV? The Rossion has a BOV that opens to release the built up pressure in the turbo line when the throttle is closed. This allows for quicker response and reduces the backpressure on the turbos.

 

yes they do.

 

if car already has after market blow off valves and they are working properly, shouldnt see that boost reading when TB closes as it would disperse the pressure to atmosphere. if it has after market diverters, these would be dispersing as well. Unless they are the adjustable kind, in which case may be the setting is too high.

from what i know of stock diverters, they have trouble holding bar pressures near 1bar and thus wouldnt expect throttle off overboost in this situation. and usually when they break, i think the result is always inability to hold pressure rather than holding too much. i could be wrong.

i never saw throttle lift over boost in my car, post exhaust, 0.8bar levels. by the time 1bar flash was done, diverters were already upgraded.

on the o2 sensors... would throw a cel if the cats are sport/race type and tune didn't provision for it. Think u got a tune if the car's boosting 0.9.

 

I had the same problem with overboosting,just changed the DV's and problem was gone.(I had the Forge dv's and changed with upgraded audi ones)

 

Dixie and Mad Ness, that's what I've come to believe. The car is flashed and I have no idea which I have. As my local tuner is playing in Germany and Stuttgart specifically(damn him, lucky dude!), I think I'll just run up to the local dyno and see what I can find out. If my A/F ratios are good, I'll feel a little better. Also seems that DVs are a quick fix for the main problem after I really figure out what I have, either from the dyno or PO. So, off to research DVs and see what might be a good fit.

 

get a durametric or brockway obd2 reader, good investment and very useful. this car has wideband sensors built in which the aforementioned can display.