[ryanmtorigian]

Hey guys, recently picked up an 04 325ci that seemingly is having some transmission problems.

The car wont take off until almost 2k rpm.

At low speeds it drive fine, but under more load the transmission slips really bad above 3-4k rpm and takes 20-30 seconds to get up to 40mph.

All the gearshifts are smooth in manual mode, but the car has a hard time with acceleration.

The gear light doesn't come on and ISTA doesn't pull any transmission related codes.

Additionally everything seems healthy engine wise and the only code is for the air pump.

At this point I'm not sure weather to just swap the transmission entirely, or If it would be worth it to try a fluid/filter replacement, or maybe just a torque convertor.

Don't really have a lot of experience with the automatic transmissions.

Read some other threads with 325s having similar issues before the transmission is fully warm, and it being fixed with a software update. But I think my symptoms are worse.

Thanks for any help!

 

[IdahoDoug]

First thing is be sure it has correct fluid level. And driving it like that is tearing holy hell out of it.

 

[el.T]

^^^^^^^^^^what he said, plus condition of fluid. At this point you will most likely need to drain, pull pan, clean magnets and pan, replace filter/gaskets, remove and test solenoids, inspect harness and sleeve, speed sensor, etc..... if a solenoid is found out of range, replace ALL with NEW ZF solenoids. This will require removing the valve body to get to the upper valve body for Pressure Solenoid (convertor). SO, since your at this stage might as well clean/bore, upgrade pressure regulator (Sonnax, TransGo), and make sure the other valves move freely. Its a fairly easy job, must be surgically clean surfaces and tools as well as schematics for which valve body bolts to remove for disassembly/reassembly. I have also found upon refilling I again drained and refilled two more times so fluid in convertor was refreshed. You wont replace all the fluid by default but the more the better. I used the prior drained fluid for these refills and final refill with new TES-295 fluid. My issue and yours very well could be similar in symptom but not similar in cause and repair......the above scenario is but one possible remedy.

The issue can be a number of things, from wiring/harness issue, intake/exhaust component, throttle body, or other..... but using data can aid in determining what's happening and not happening, activating components, and logging/monitoring output speeds and voltages.

Poor grounds and low voltages or spikes can cause EGS/ABS/EML blips also which will cause reductions in power..... Harder to chase but still needs to be done to eliminate things.
Regardless you will find within this forum all the articles you will ever need to perform an oil/filter change to complete rebuild of entire trans. Search this info, read it, know it, and be comfortable understanding the task/s before removing the first bolt as well as part names, numbers, and runs and changes during model years. Identify by the tag on the bottom of body/pan.

The information available to you here is priceless as not only will you become knowledgeable of your car, you will also learn of the mistakes made so you don't do the job three or four times........although many of us have......admittedly..