[s-cars] Drastic Power Loss-So far No Joy

[Manuel Sanchez]

S-heads,

Still hunting for whatever is causing my drastic cut off of power  
near peak boost. This happens with my MRC RS2 software in my ECU as  
well as with a bone stock ECU. So with my RS2 ECU I hit the wall at  
about 26-27 psi, when the Stock ECU is installed (with the stock  
injectors) I hit the wall at about 13-14 psi.

Many of you have suggested I'm experiencing an Over Boost situation  
and have given me some avenues to pursue, here's what's been done today:

1. My RS2 WGFV
Checked with a multimeter, and it's within spec

2. Other used, Stock OEM N75 WGFV
Checked with multi-meter, within spec
Installed in my car, test drive results in the drastic cut off in  
power (nuts)

3. Inspect Wastegate Diaphram
No tears are apparent. Will test vacuum on this tomorrow hopefully.

4. Turbo Outlet hose and Wastegate hose (that small diameter crinkled  
and ultra expensive bugger).
Swapped these hoses, as well as this other stock N75 WGFV into my  
car, same boat anchor results


Some people have suggested the altitude sensor, hopefully I can check  
that soon.

What's puzzling, is that I think many of these electronic items would  
throw a code if they were malfunctioning, no? Previously the only  
codes I had been receiving were :

00537 – Oxygen Sensor Control
Maximum Control Level Exceeded

Condition:
Fuel Tank Low resulting in fuel system pressure less than 3.3 bar (48  
psi) [Note tank was ¾ full as indicated on fuel gauge]
Ignition System Failure

Symptom:
CO before 3 way catalytic converter less than 0.5% (Hmmm, what could  
this mean???)
Fuel Consumption high

Repair:
Fill Fuel Tank (tank had plenty of gas, and fuel gauge reads accurately)

00537 – Oxygen Sensor Control
Minimum Control Limit Exceeded

Condition:
Engine Intake Air Leak after Mass Air Flow Sensor-G-70
Leak in Exhaust System in front of 3 way catalytic converter
Heated Oxygen Sensor (HO2S)-G39-malfunctioning
Fuel System Pressure greater than 4 bar (58 psi) [This is  
interesting, seems like I will throw this code all the time if I set  
the Fuel Pressure to 4 Bar/58 psi, which is what I believe I’ve been  
told is the Fuel Pressure for RS2’d cars. True?]

Symptom:
Rich Exhaust
Spark Plug Fouling
CO before 3 way catalytic converter greater than 3%

Repair:
Repair Leak
Check HO2S-G39
Check Fuel System Pressure
00561-Mixture Adjustment
Adaptation Limit (mul) exceeded
Condition:
Fuel System Pressure too low
Spark Plugs, ignition coil, ignition coil power output stage  
malfunctioning
Symptom:
Reduced Fuel Economy (no kidding)
Sooty Exhaust (yeah, in spades)
Repair:
Fill Fuel Tank
Repair Leakage
Check Fuel System
Check Fuel System Pressure
Check G70 (Mass Air Flow Sensor) [We cleaned the OEM MAF with MAF  
Cleaner, and we also installed a brand new RS2 MAF-we still had the  
drastic engine cut-off]


Lately  we've been thinking that whatever the fault is, it's  
something mechanical as opposed to electrical (that would throw a code).


Some people have suggested  a few things that we haven't had time to  
try yet:

Altitude sensor

Check the wiring between the MAF and ECU with an ohmmeter

Throttle Position Sensor - the ECU allows boost only when the  
throttle position sensor is above a certain value. So you could check  
the sensor

Light on the fuel pump to see if it's getting cut off when the Cut in  
Power occurs (I'm not exactly sure how to rig this up actually),

Hopefully I can check these soon.


Any other ideas are greatly appreciated.


Thanks.

-Manny
95 UrS6 (still kickin my arse)