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JKO_ZHP
07-22-2018, 06:06 PM
2005, auto/steptronic. Been getting average 25+MPG cruising on the highways for the better part of the year, both pre and post-limp mode.
Just 7,xxx miles away from 200,000 miles even....I'm determined to make it there - but limp mode keeps coming back.

First time it happened last week, car was cruising at around 80MPH, ~3K RPM. Red battery light flashed a couple times, then dash beeped once, all needles dipped to 0 for a brief second, then returned to what it was just seconds before, albeit much tougher to maintain speed. Rough deceleration/acceleration as gears go down/up.
The lights that came on were: yellow DSC, yellow Brake, yellow gear/cog indicator next to current gear, and SES.

Did a quick guess-and-check: found out that the transmission fluid was low, and very dirty - flushed & changed it, new filter kit.

Shifted much better afterwards, but the same limp mode lights came back on not long after (within a couple days) - did a voltage test and deemed it to be a failing alternator. Replaced it with a brand new Bosch (AL0816N). Previous one was a remanufactured one which was about two years old; about the same time they usually fail, based on what I've researched online - hence, the brand-new Bosch one this time around vs. another reman'd.

Drove perfectly fine for the last week - but today, while cruising around 80MPH again with RPM's in the 2.75-3.00K's, I turned on the radio. Not long after, same original symptoms appeared (flashing red battery light followed by the yellow lights, loss of power, etc.). Turned the car off, came back after an hour or so, drove 100% fine. Didn't turn on the radio this time, drove home just fine (over 60 miles cruising between 65-85MPH).

Did a search here and E46f. - it seems that the battery may be on it's way out; any other thoughts as to what could cause the above? I put in a 49-DL (Duralast; discontinued) myself about 4-5 years ago, which seemed like the approx. range for when it would lose enough juice to cause problems.

Any ideas? I'd throw in a new battery but not without knowing the other possibilities/non-battery issues first.

On a side note, entire cooling system has been replaced once already a year or so ago - but the coolant light came on just last week, and stays on. No leaks; temp. needle is always dead center, didn't even need to top off. Have Mishimoto upper & lower hoses, and the other 5 OE hoses/pipes on the way for replacement, along with a new OE expansion tank & thermostat as a precaution.

Thoughts would be appreciated...

san
07-23-2018, 04:32 AM
I would have the battery checked. Not sure how thorough the tests are but stores like auto zone can test a battery and let you know if it’s failing.


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ZHPizza
07-23-2018, 05:23 AM
I would have the battery checked. Not sure how thorough the tests are but stores like auto zone can test a battery and let you know if it’s failing.


Sent from my iPhone using TapatalkSounds more like alternator to me but AutoZone can check that too

san
07-23-2018, 05:25 AM
Sounds more like alternator to me but AutoZone can check that too

OP said a new Bosch alternator was installed so I assumed it would work fine. Doesn’t hurt to check though, especially if the battery is tested to be good.


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ZHPizza
07-23-2018, 05:27 AM
OP said a new Bosch alternator was installed so I assumed it would work fine. Doesn’t hurt to check though, especially if the battery is tested to be good.


Sent from my iPhone using TapatalkLook at Mr read the whole post over here

san
07-23-2018, 05:31 AM
Look at Mr read the whole post over here

[emoji51]


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Sockethead
07-23-2018, 07:40 AM
My vote is battery. It needs to be load tested. Putting a volt meter across it is just testing the surface charge.

JKO_ZHP
07-23-2018, 07:41 AM
I would have the battery checked. Not sure how thorough the tests are but stores like auto zone can test a battery and let you know if it’s failing.


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Sounds good. I'll stop by later today.


Sounds more like alternator to me but AutoZone can check that too

OP said a new Bosch alternator was installed so I assumed it would work fine. Doesn’t hurt to check though, especially if the battery is tested to be good.


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Could be...the original alternator was replaced with a remanufactured Bosch one. It failed same-day and we had to get a warranty replacement. This is a new one altogether but with the luck I've been having lately, it won't hurt to check it all out.

az3579
07-23-2018, 11:37 AM
I would have the battery checked. Not sure how thorough the tests are but stores like auto zone can test a battery and let you know if it’s failing.


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This. Advance Auto tested my battery and it tested good; still turned out to be bad, because a new battery solved the issue I was having at the time.

JKO_ZHP
07-23-2018, 02:58 PM
My vote is battery. It needs to be load tested. Putting a volt meter across it is just testing the surface charge.


This. Advance Auto tested my battery and it tested good; still turned out to be bad, because a new battery solved the issue I was having at the time.

I spoke with my guy at the shop (the one responsible for having carried this car to its current mileage) and apparently the symptoms I described above matched 100% with another previous customer of his - a Dakar Yellow E46 M3, manual. Turns out it was a wiring issue for him; the only difference was that his radio crackled when on while mine works fine but will cause the above to happen within minutes at higher MPH/RPMs.

Either way, we'll thoroughly test the battery since it's been a few years since it was replaced, as well as explore whatever was the problem for that E46 M3 then.

Thanks -

az3579
07-23-2018, 03:41 PM
Also check the ground points and make sure they're not corroded or oxidized.

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ELCID86
07-23-2018, 05:41 PM
This. Advance Auto tested my battery and it tested good; still turned out to be bad, because a new battery solved the issue I was having at the time.

Same with my Wife’s (old) TSX.

BMWCurves
07-24-2018, 09:26 AM
As an aside, I had no battery or electrical issues, but my speakers would pop when I turned on the car. It turned out my batter was 11 years old when I replaced it. Solved the crackling issues. I think the E46 is particularly sensitive to battery voltage fluctuations from all the stories I've heard, and anything outside of the optimum range causes weird electrical issues.