dustinr

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?

Kevin

Are you running a EBC? 91 octane at 1.2bars?

Have you done any logs?

Your throttle-body is closing.

Why are you running a K&N filter? What is your MAF reading?

dustinr

No EBC... I wanted the car to be able to detune itself if need be.

I run 93 to 95 octane most the time, but have to run crappy 91 sometimes when I venture into CA, but the map I had installed is a 91 octane map.

I haven't data logged at WOT yet as I wasn't sure what parameters to check (Durametric only allows for 8) and a lot of the parameters are very similar in description.

I data logged at idle and the "Hot Film MAF" was reading normal but as stated above I haven't done a WOT data log yet.

What's wrong the K & N? what's better with a stock air box?

Kevin

Go and find my new Datalogger thread. There are values shown that you should use.

The K&N eats MAF's.... Do a search about oil filters and MAF's...

Question> why haven't you called your tuner??

911SLOW

Perhaps the DME tuning went bad indeed..

Good luck fixing it.


P1508
Torque comparison function monitor - signal
implausible

Diagnosis conditions
• Engine speed greater than 1,120 rpm


Possible fault cause
♦ DME control module faulty


Affected terminals
Diagnosis/troubleshooting
Work instruction
1 Replace DME control module
Display OK If not OK
⇒ Step 2
Perform adaptation
♦ Switch on the ignition
♦ Wait one minute
♦ Do not press the accelerator
♦ Switch off the ignition for at
least 10 seconds
♦ Read out the fault memory

haulinkraut

Exactly. Is your hardware matched up with the tune you are running? DME tunes usually don't just go bad. They are either bad or not. The DME can be faulty or the sensors feeding the DME. I would suspect a hardware/software missmatch or a sensor failure. Possible even an incorrectly adjusted wastegate.

SoloRacer

I have the same thing a happening to me. I just turn off the car, restart and everything is fine. When I was at the track it was happening every 15 minutes under track conditions. On the street it has happened a few times. Like you I am not sure what to do. My car has a pair of AMS billet K16's and a tune by EPL. I am still running my low boost tune (1 bar). I am tempted to change the MAF to see if that makes a difference.