Hello everyone,

I'm looking for some advice:

M104 2.8 loses power (~30%) in certain driving conditions, especially when engine is hot. It seems like the ECU goes in limp mode, as the engine will always run normally after a restart.

This condition occurs when revving the engine over ~4000 rpm (I guess the fault happens only under full load). Anyway, problem continues through the whole rpm range, however the car is drivable and still smooth with less power. After a restart, it runs nicely and with full power, unless I rev it over 4-5 krpm.

There's also a slight difference in exhaust sounds during the power loss (become more howling at full throttle). Sometimes when stopping, idle rpm will be too high (around 1500rpm), which never occurs when engine is running normally.

Replaced: primary ignition (12V) wiring, the ignition coils, spark plugs, high voltage cables to the plugs and the short "boots" for coils. May be a harness issue as it's the original one (except ignition wires).

Neither disconnecting O2 sensor nor unplugging MAF will make a difference.

Any help (especially good HFM knowledge will be greatly appreciated.

/Tabasc0/