My BMW 130 has a problem, as soon as you acelerate there is no power, uphill I need to go back to 4th gear. DId a full service (plugs, oil, filters, battery even) DId the diagnostic test and it shows "no code", don't know if thats the problem and no hazard lights came on and I am a normal female driver,

Which transmission does yours have 4T65-E or 4T80-E ?

4T80-E
No Fourth Gear

Checks

Causes

1-2 Shift Solenoid Valve
?€¢
Inoperative
?€¢
Debris
?€¢
Pinched wires

3-4 Shift Valve Bore Plug

Misassembled

4th Band

Burned, slipping, missing

4th Servo Cover

Cracked

4th Servo Pin

Broken, seized

4th Servo Piston

Damaged

4th Servo Seals

Rolled, cut or damaged
4T65-E
Slipping or No Fourth Gear
Slipping or No Fourth Gear Checks
Cause

DEFINITION: A large engine RPM increase is noted in fourth gear, Drive range, with little or no vehicle forward speed increase. First, second, and third gear operation are normal. Shifts into fourth gear are soft or do not occur. Fourth gear ratio is 0.705:1.

Automatic Transmission Fluid Level
Low fluid level

Transmission Main Line Pressure
Low transmission main line pressure

Oil Filter Assembly
• The oil filter assembly (100) is missing, plugged, or damaged.
• The oil filter seal assembly (101) is missing or is damaged.

Control Valve Body Assembly
• The 3-4 shift valve (362) or the 4-3 manual downshift valve (360) is stuck or binding.
• Debris is found in the passages of the control valve body (301) or of the control valve body spacer plate and gasket assembly (396)

Case Cover Assembly
Distortion or damage occurs at the manual valve (404) or at the case cover (401), causing PRN oil leak.

Driven Sprocket Support Assembly
A plugged third clutch oil passage in the driven sprocket support assembly (609)

Fourth Clutch Assembly
• The clutch plates (500-502) are worn, damaged, or misassembled.
• A missing or not seated fourth clutch spring retaining ring (601)
• A damaged spring assembly (602) or piston (603)
• Worn or damaged fourth clutch piston seals (604, 605)

Third Clutch Sprag Assembly
• The sprag (720) was misassembled or backwards on the inner race (661).
• A damaged third clutch sprag assembly (653, 661, 719-721)

IMO it's more likely that you have the wrong grade of ATF. It's very important to have the correct grade. The following site shows this:
http://www.nairaland.com/1364064/automatic-gearbox-problems
each car manufacturer has recommended grades of Automatic Transmission Fluid, BMW is no exception. the following website for BMWs may bring you more accurate data:
http://www.nairaland.com/1364064/automatic-gearbox-problems
Apparently CTSC is the supplier for BMWs via the web.
Generally auto gearboxes have drain plugs and filler plugs to enable oil change in routine maintenance. But I would definately go back to the garage where you had the last service and ask politely about the grade of ATF used, before considering an 'oil change'.
Good Luck

it could be your plug wires or the timing

i would say you have a problem with the computer that controls the tranny i just went through this with a jeep we changed the solenoids and no luck so we changed the computer and it fixed it right up

Download this link and find your Service manual for your vehicle. It will serve you well and to keep for future reference

http://ezinearticles.com/?Find-the-Free-Auto-Repair-Manual-You-Need-Online&id=92717

You can guess all you want but if you have a oil problem then damage is being done to the engine. Unless you can afford to replace the engine I would get it in ASAP so a professional can look at it. You could replace the filter yourself to verify your question. You dont need to change the oil now to verify this. Bwm's oil filters do tend to fall apart within 6000 miles and the service interval is 12,000 to 15,000 depending on the year

It seems to me by the way you describe it to me that your modulator valve is faulty or needs adjustment. If you have a manual for this transmission I ques it is a little ZF,
Look up and try and find the modulator valve and try to adjust it if you want to do it your self and see adjustment in your manual.

yeah it could be full of water in the gas you bought. see if you can pull a sample and check. start looking at the filters.

go back & sleep with the mechanic, that always works for my sister.