Have BMW 2000 323 ci E46, tried to get it ready for DEQ, I have no CEL but Cheap-o-code reader shows P0170 and P0173 -Fuel Trim Bank one and 2. Any tips? Any capable BMW code reader to recommend (Ancel BM700, foxwell nt530 or inpa)?
Tips to follow:
P0170 and P0173 are codes for the MS42 DME, so you must be working on your 323ci.
The codes don’t tell you if the problem is a rich or lean problem. You are going to have to look at your fuel trims to work that one out. Look at all 4 of the furl trims, 2 short term and 2 long term.
If the long term ones are negative, then you have a rich condition and the DME is reducing the amount of fuel (negative trims).
If the long term ones are positive, then you have a lean condition and the DME is adding fuel (positive trims).
Have a look at the trims and tell us what they are. We’ll then help you through the diagnosis and repairs.
You need to get a more capable BMW code reader.
As far as scanners is concerned, I use the following:
1) INPA software running on a Window lap top/surface Pro with the cheap special cable.
2) Foxwell NT530 OBD2 scanner with BMW software. See Here.
Fixing fuel trim problems is best done with an OBD2 scanner. The fuel trims are in % and make sense. The BMW software fuel trims data is confusing.