4.8is transmission journey from broke to ballin'

[PropellerHead]

I'd spend a lot of time retelling the story of my journey starting in 2004 from a 2004 3.0 to my epic find of a 12k mile 2004 4.8is in 2011. But most of the regulars have heard that.

I even wrote about some other dirty little secrets I've talked about- and read about from others- here on the board.

• The seemingly random gear shifts that happened even in manual mode (impossible). I wrote about that somewhere around here, too.
• The transmission hanging on to a gear in Sport Auto mode so long that it was silly. (I could not ever find a way to describe this)
• The ultra-hard 1-2 shifts on a cold motor in cooler weather- <40 degrees F.
• The flashing check engine light and ridiculously rough idle at the same temps. All was fine after warm up that same cold day.
• That weird downshift at highway speed that made it feel like you'd dropped a whole transmission.
• The slipping feeling that would come up at random shift points in city traffic.

Some of the things I kept to myself. I either couldn't describe it just the right way or I'd read that the problem was a solenoid, new transmission fluid, a filter, a TQ converter, or one easy to understand DIY fix or another.

I never wanted to admit that I'd accepted driving my dream X5 was only about 95% as much fun as I'd hoped for. But I read and I read and I read that BMW just got it wrong on E53. Transmissions, sunroofs, window regulators, seals, and the N62. All wrong. I was forced to admit within my own head that I sold a well sorted 3.0 with no problems for a low mileage 4.8is that was fast as balls and drove like a dream once it warmed up. What's the occasional hard 1-2 shift between seasons anyway, right?

So, after the around town slips became a bit more frequent, and with our 2nd wild West ~6,000 mile Summer '15 trip looming, I decided to take it in once and for all. I would confess to my friend and trusted indy of nearly 20 years that I didn't like cold 1-2 shifts. I would confess that it was slipping around town and that very unsettling slam at highway speed down shifts. I would accept and start planning for a $7000 withdrawal from the I-drive-a-V8-E53 fund.

Oh yes, I was going to keep it. I just needed to do some planning. Maybe delay the '75 2002 restoration while I fix up the yard and the X5. Hands off my supercharged E39. That's not going anywhere.

So, about 6 weeks ago, colder weather at the ready, I dropped it off as I left town. Take your time. If it's $16k, maybe I don't keep it. Maybe the dream is over. Maybe I can find a nice 2014 like my brother did last month.

Here's where it got great:

Trip 1:
Drop the tranny, replace a gasket that frequently fails and causes rough shifting. Gasket not obviously damaged. Transmission fluid flush and fill. Same filter- replaced ~25k ago. Agree to replace filter and fluid at next interval- ~90k miles.

Mark off driveshaft to look for slippage. None found.

Diagnose rough idle through codes. Replace engine module that handles the same items as faulted in codes.

Diagnose air suspension. I heard audible air leakage while parked. Turns out this was a wheel problem. Found some leaking stems. Leveled the suspension.

Cost: $700

Result: No rough idle! No more rough 1-2 shifts when cold! Sport auto mode WORKS without hanging on to a gear like a freshman virgin does a senior suitor. It was SO nice! I was happy! But could I be MORE happy?

The slip returned. But while we were screwing around with other cool things like getting the windows to roll up with the key, we found a new transmission code may be the solution.

Trip 2:
Level suspension again based on tires that retain air.

Check markings on drive shaft. X Drive is known to be thrown when a wheel (or two) is out of sync with the others. No slippage found.

Cost: $0.

Result:Level suspension. Slippage around town reoccurs. No rough idle. No rough 1-2 shifts. Rough shifts at highway speeds not observed.

Trip 3:
Apply transmission update from trip 1. Programmed with transmission firware(?) update.

Alarm suddenly tripping after like 1 min armed. Disconnect hood switch. Problem solved.

Cost:$200

Result: It's a whole new ride! I can run around in Sport Auto mode and not wonder when it will shift! A cold morning renders spot on 1-2 shifts without shake or CE lights. I'm so used to driving cautiously under these conditions that I find myself forgetting I have a 'normal' car again! I can get in on a ~55F morning, no shake at idle, and hammer that 1-2 shift in sport! It acts like it's SUPPOSED to.

So, yes. Maybe BMW *did* get it wrong on a few combinations of software, hardware, and usage conditions, but I came to realize something *very* key:

By now- and probably while the E53 was still in production- BMW figured out how to fix it. They released firmware, they issued new parts, and the well trained, curious, and experienced independent network has the ability to solve these problems. We just need to offer them the chance to fix them.

If you're putzing around in what used to be the SUV flagship for BMW and you're having these little issues that drive you nuts, take some time. Find a mechanic that owns one. See if he can download updates n addition to parts at the problem. Ask about his diagnostic process.

I was completely floored that my rough idle was a $100 engine module. I was equally surprised to find my transmission woes solved with a $30 part and some firmware.

If it sounds like I am happy to have dropped $1000 on my E53, you're damn right I am. Not only is it way better than I expected, I faced my fears head on and got an answer that surprised me:

The E53 is supposed to act like any other BMW. At this point, all that is keeping it from the full potential is the owner and- where necessary- the right diagnostic partner.