new alternator cause a throttle body issue? Help!!

[brokenagain]

Hi Guys, I have a 2002 540i/6.

My car just recently died in my driveway I had the battery tested first and it tested good despite being almost 6 years old and found out it was the Alternator. I changed it out with a new Bosch liquid cooled and when I went to start the car the throttle body started acting crazy. I recently changed it out about a year ago with a new VDO Part from FCP euro and its been working flawless up until this day so I was a bit confused. After multiple adaptation resets and some additional codes for the MAF I order a new Bosch MAF and a replacement VDO throttle body from FCP. After resetting the adaptations and installing everything the car was running normal again. A few days later I drove a 500 mile roundtrip and she ran great. Its now the weekend and the car sits for a few days and Bam! throttle body codes again. Now im stuck on the side of the road in limp mode and manage to reset the throttle body and it seems ok for the moment but low and behold it happens again and I'm still dealing with stalling, erratic idle, limp mode. etc.

The question I have is after all of this, could the battery be the culprit? could the battery be failing and causing issues with my throttle response? I did also notice that the battery has some acid build up around the water cover which I don't remember from a few weeks back. First thing tomorrow I'm going to buy a new battery and go from there. I checked the voltage at the battery when the car is running its around 14.3v

Anyone else deal with something similar?

[shogun]

Moved from E39 Common Problems and DIY Fixes to E39 forum, post questions in the normal forum

[jicaino]

If you have a data logging obdii device monitpr voltage. If the voltage regulator is questionable it might do that and it won't throw or store specific codes. Also you could open your drivers side e-box and check the condition of the spliced diode (follow the thicker red wire.coming from the alternator, not the one going to the battery post on top of the valve cover but the other one) also a good way to reset adaptations is get in the car, press gas pedal to the metal, turn to IGN2, wait 30 seconds, turn to IGN0 and then remove your foot from the gas pedal.

[JimLev]

^That’s not the way to sync the throttle body to the DME.
You don’t touch the gas pedal.

[jicaino]

^That’s not the way to sync the throttle body to the DME.
You don’t touch the gas pedal.

Doesn't that erase adaptations? Sometimes a series of tension spikes interferes with adaptations values and then hell arises. Double checking I see I didn't mentioned sync of the TB potentiometers (pedal and actual TB) but erasing adaptations.

[JimLev]

Doesn't that erase adaptations? Sometimes a series of tension spikes interferes with adaptations values and then hell arises. Double checking I see I didn't mentioned sync of the TB potentiometers (pedal and actual TB) but erasing adaptations.

I’ve only erased the adaptations using INPA or my Foxwell.
To sync the TB to the DME,
1) key in position 2, engine not running, leave in pos 2 for at least 30 seconds. Don’t touch the gas pedal
2) Turn key off.
3) Start engine, your done.

This needs to be done when a new/different TB is replaced with a different TB.

[jicaino]

I've used the gas pedal thing many times. I lifted that up from some technical bulletins, I'm going to see if u can find them again, the only thing that I've read about leaving key in ign2 for a long time is for erasing codes such as misfires, brake pad wear sensors, etc. I don't recall seeing nothing about "sync TB to DME" in any tech bulletin or other literature. I don't think there's variances in US vs other market SQ versions. This is super interesting. Will see if I can find anything about the 2 very different methods we've described

[brokenagain]

I've used the gas pedal thing many times. I lifted that up from some technical bulletins, I'm going to see if u can find them again, the only thing that I've read about leaving key in ign2 for a long time is for erasing codes such as misfires, brake pad wear sensors, etc. I don't recall seeing nothing about "sync TB to DME" in any tech bulletin or other literature. I don't think there's variances in US vs other market SQ versions. This is super interesting. Will see if I can find anything about the 2 very different methods we've described

You're correct. To reset the adaptations i press the gas to the floor, then turn the ignition to position 2. Do not start and wait 30-45 seconds then take out the key with the accelerator still pressed then release and wait another 30-45 and you should be good. Ive probably done that 30 different times over the last two years and its always worked. I also have the Schwaben BMW scanner from ECS which can clear the DME codes much like INPA.


Update: After putting in a new battery it seemed to help but ended up with some more idle issues after driving a while. Afterward I started playing around with the TB harness by pushing it into the throttle body a bit further, there is a very slight amount of play. Once I pressed it tighter it started acting really erratic and I figured there might some debris or grease inside the port. So I cleaned inside the harness and throttle body connection, cleared the codes and everything seems to be working as it should. Fingers Crossed.

Thanks for the help

[jicaino]

You're correct. To reset the adaptations i press the gas to the floor, then turn the ignition to position 2. Do not start and wait 30-45 seconds then take out the key with the accelerator still pressed then release and wait another 30-45 and you should be good. Ive probably done that 30 different times over the last two years and its always worked. I also have the Schwaben BMW scanner from ECS which can clear the DME codes much like INPA.


Update: After putting in a new battery it seemed to help but ended up with some more idle issues after driving a while. Afterward I started playing around with the TB harness by pushing it into the throttle body a bit further, there is a very slight amount of play. Once I pressed it tighter it started acting really erratic and I figured there might some debris or grease inside the port. So I cleaned inside the harness and throttle body connection, cleared the codes and everything seems to be working as it should. Fingers Crossed.

Thanks for the help

As our car ages, there's plenty of gremlins that occurs only on contacts being dirty or oxidized. I've been clued in Caig deoxIt products by either JimLev, GearGrinder, or BimmerMeUpSnotty (sorry guys, I don't remember which guru enlightened me)

I'm a fan of that now. It cleans and removes crust off every piece of electrical connection you find.