Thread: D3 Reduced engine performance.

Hey Guys

Greetings. I'm new to this forum and would like to start out by throwing a challenge out there.
I have a D3 (2005) 4.4L V8. I've had it since 2009 and it was fitted with an LPG conversion (injection) when I bought it.
It has about 280,000ks on it and still runs like a dream.
However, it is throwing up some OBD codes P0170 and P0173 are fuel trim malfunctions (banks 1 & 2). I know these are because of the gas system so these aren't an issue.
It also comes up with P0172 and P0175 (System too rich - banks 1 and 2) which I also assume are due to the gas system.
However, recently it has been showing "Engine fault" on the dashboard LCD screen and sometimes it also shows "Reduced engine performance". The only way I can clear this is to either stop the car and re-start it or clear the codes whilst on the move.
Weirdly enough, there is one stretch of road where I can almost guarantee that it will do this. It is on a stretch of freeway which is ever so slightly down hill. If I'm travelling along there at 100kmh with the cruise control on, it will come up with "reduced engine performance" probably over 90% of the time.
It also logs misfire codes too but for the most part, the motor runs perfectly (on LPG and petrol) and only very occasionally do I get a misfire.
The misfire and the reduced engine performance never seem to coincide though.

I have had new plugs fitted, replaced the MAF sensor and also I have new CO2 sensors that need to be fitted (I just have to find the time to fit them).

Any ideas where else I might look?

Thanks
Neil

Cheers Graeme.

Before I do anything else, I will make sure the air filter is clean and change out the CO2 sensors. I'll report back after I've done it.