So I had a K24/18G conversion done with 1 bar waste gates, turbo intake hose kit installed (not boost), diverter valves, exhaust, 5 bar FPR, stock air box, K & N filter and Softronic tune...

Car is fine driving around normally and is even good upwards of 1.1 to 1.2 bar.

BUT... if I try to drive it hard from down low, WOT in say 3rd gear, the boost kicks in massively and then it all of a sudden dumps boost, and the CEL light comes on and the gas pedal no longer functions. Engine is still running but wont allow for any gas input and the CEL screem says drive to dealer. Turn the car off and back on and everything is fine...CEL is still on but car drives fine normally.

Hooked up Durametric and the code is P1508 Torque Comparison Function Monitor - Signal Implausible (Porsche code 408)
Cleared it and it was fine...

But now I'm afraid to open it up WOT...

I've done some searching and some people say that the MAF is bad... but that doesn't make sense because it didn't throw a MAF code. And I figure with electronics they either work or they don't.

Then others say the DME is bad... and that didn't make any sense either because if it was bad why would it continue to work and only glitch under high load, high boost. It doesn't have any CEL's at all till you WOT under high load condition.

Anybody else running higher boost (cfm) have similar problems?

Is the stock MAF not able to handle the additional air flow?

 

I would start with a boost leak test if they didn't do before you took delivery of the car....
and they need to do it from the turbos... they block one off and pressure test from the other side.... when that passes then you zeroed out about 30 things.... if not then you probably will find the cause... But before the boost leak test have the car idling .... disconnect the maf harness and see if the engines rpms drop and or increase a bit... if so that means your MAF sensor is working... if not then its your MAF sensor...
this is what I would do before I would start spending all sorts of money....

mark

 

Is that what the Torque Comparison is? One bank is getting more boost and therefore more torque?

I'm glad you responded, all the parts came from your store, I just had a local shop install it. Funny thing is, is that I asked for them specifically to boost test it when they had finished but going back over my paperwork I don't see were they did.

But if it was boost leaking wouldn't the car sense that given any boost at all?

 

putting on a 18g wheel upgrade from a K24 standard on your car, 5 bar FPR, filter, and intake from airbox to turbos will not cause any such issues.... I dont want to blame the tune( softronic is good).... it usually isnt that either.... but do remember you are now boosting probably 1.2 bar vs .8 stock... things change... thus install is important... a missed hose, a vacuum line to the 5 bar, a maf now that isnt liking it etc.... it can be any of those things...
so dont panic... get them to do a boost leak test.. have Ryan call me.... do the smart basic stuff... you will find the issue.... disconnect the battery for an hour as well...
why dont you log a 3rd gear pull from 22-- rpms to 6500 rpms to see what's really going on? get your tuner involved in on it as well...
log:
rpms
engine load,
ignition angle
oxygen sensing actual value bank 1 and 2
boost pressure of sensor
setpoint boost..

mark

 

When data logging...

Start at 2200 RPM and then WOT to 6500 RPM?

I've attempted to contact Softronic and they haven't gotten back to me yet.

Ryan and the guys at Rennsport are awesome but I don't think they have much experience with these newer turbo cars and modifying and tuning so it's a learning curve for them as well. They build a lot of Porsche race cars but most of those are NA or old school single turbo. So any insight you can provide them is appreciated.

I'm excited about this project, I just hope we can sort the code thing out quickly and cheaply.

Thanks again...

 

Are the waste gates balanced?

 

its happening to me now, car still in the dealer !!

the code which in the durmatric is :

- P2201
throuttle/pedal postion sensor "A" circuilt low value below
lower limit value

they changed the pedal but still !!!!!
they think that the DME failed

 

996TT OBD II DME 7.8 WKD 484 120.pdf.pdf

According to the manual, the DME needs to be replaced..

 

from where you got the codes manual ??

thanks

 

Here:

http://locodemoto.com/tech/996turbo/996turbo.zip

It's for the 996TT, DME 7.8

 

rep for you

thanks

 

I know Emanuele is very smart and has learned a lot in one year.

 

putting on 18gs and a 5 bar has nothing to do with a failed ECU. that ECU was already flashed by softronic. I believe he reflashed it for the 18gs... I believe this members issue is during install... not a ECU issue... from what it seems like the issue was not there before the install... therefore it must have happened during....
markski

 

Mark is correct, mine only happened after I had the k24/18g modification and flash done... I don't think it's the DME...Lord willing it's not.

 

Well I hope the DME it's ok too...I just did a "copy and paste" from the book lol...

Did you notice how much boost right before it shuts off?

I finished my car few days ago, boost comes on pretty fast but still very linear.


Maybe datalogging trying to replicate the issue would be a good thing..you (and your tuner) could see what's happening right before the event....
I would check the wastegates setting anyway and do a boost leak test. It doesn't hurt in any case..