When I bought this little nugget of a BMW, I received no maintenance history to speak of, in addition to the plethora of painfully obvious problems. So, I figured I would start from scratch. After all, if this poor neglected car is going to survive my less-than-gentle driving style, she could use a clean bill of health to start with. Unfortunately for the E82, this meant having to rely on my haphazard wrenching skills.
The first step was to pull the car into the garage, ready the jack stands, and get to work. It should be noted that at this time, I still had my former Honda S2000, which has since been sold in favor of an F87 BMW M2 — but alas, that is a tale for another time.
Tracking Down and Clearing Codes: I then got started trying to track down and resolve most of the errors in the DME, of which there were so many I hardly knew where to start. The vast majority of them were some type of CAN BUS errors.
One of them was a seatbelt tensioner error. I don't know about you, but when I think of seatbelt tensioners, I imagine the part that actually retracts, seemingly applying tension to the belt. Apparently, the Germans and I have different ideas about what words mean. I picked up a brand-new seatbelt tensioner, which is actually the buckle that attaches to the seat. Through my exhaustive search of the Intarwebs, I learned that if you're in an accident, the plastic piece on the "tensioner" can stretch, causing a tensioner code. So, I took maybe 30 minutes of my day and swapped it out. The result? My airbag and seatbelt lights went away, along with all related codes, never to return again! So far, we were off to a good start.
I then set about trying to clear up the rest of these pesky codes. I replaced a handful of light bulbs—easy stuff, with all warnings going away after a quick reset.
To get rid of the moonroof codes, I just needed to go through a factory reset process I found online, which took all of 1-2 minutes, and the codes were immediately resolved. As it turned out, the moonroof was in perfect working order with no work needed. I'm always excited when codes go away for the low, low price of zero dollars!
I then got to troubleshooting the CAN BUS codes. As dumb luck would have it, the majority of them were related to the TPMS system. Like a treasure hunter, I searched for this mystical TPMS control module and soon located the source of my problems.
The TPMS control module sits in a piece of molded black styrofoam in the right rear portion of the trunk.
When I found the TPMS control module, it was literally submerged in a few gallons of water.
I drilled a couple of drain holes in both the trunk and the molded styrofoam to allow the water to drain out and ensure this wouldn't be a recurring issue. I later dried the area and applied some paint to the holes I drilled to prevent rust from setting in.
Now listen, I'm no mechanic, but I learned a lesson about submerging electronics in water when I was a kid. As it turns out, it's not entirely helpful. After everything dried out, I ordered a used TPMS module off eBay for a whopping $57 and plugged it in. To my complete and utter astonishment, about 90% of the codes within the DME immediately vanished into thin air. My jaw dropped at how many codes were being thrown by this one module, but I knew better than to complain!
For all the codes it was throwing, only one of them was actually a check engine light, and it was related to the DMTL pump. Do you remember that picture from the previous blog post where the car was damaged on the rear right side? Would you like to take an educated guess as to where the DMTL is located? You guessed it: the right rear side of the car.
As it turns out, I live in an emissions-controlled area. I couldn't tell you what a DMTL pump does or even what the letters stand for, but here's what I can tell you: without this little box in fully functional condition, the fine folks at my local emissions testing station will turn you around and send you packing — without passing Go or collecting a set of license plates. So, the fine folks at FCP Euro shipped me a brand-new Bosch DMTL pump for what seemed to be a reasonable price (around $67). Since it was connected to the OEM charcoal canister, I figured I’d pick up a used charcoal canister off eBay in case both were damaged in the accident. They were surprisingly easy to swap out in just a few minutes. Afterwards, I cleared the codes, took a low-speed spin down to my local emissions testing station, and voilà — she passed with ease!
Beefing Up the Cooling System: After trying to chase down every stray code in the DME, there was still one more code I needed to resolve for my own peace of mind: an error with the water/coolant pump. To my knowledge, pretty much all N5x-series powered BMWs have electric water pumps. Coincidentally, they also all seem to have problems with failing electronic water pumps, to varying degrees. I’ve been led to believe it’s not so much the "mechanical" portion of the pumps that fail, but rather the electronics that control them, which seem to be the culprit, frequently throwing a code when they’re in the early stages of failure.
In my simplistic, primate brain, I can’t fathom the idea of not going down the "while I’m in there" rabbit hole. If I’m going through the trouble of replacing a not-so-easy-to-get-to water pump, I might as well replace the thermostat and hoses while I’m tearing everything apart... and if I’m already draining the coolant, removing the radiator fan, and replacing the hoses, this is an excellent excuse to upgrade the OEM plastic end-tank radiator with this beautiful all-aluminum piece from CSF.
I also figured I’d replace a few more things "while I was in there" to keep the car happily chugging along for years to come. In addition to the upgraded radiator, water pump, thermostat, and radiator hoses, I replaced the engine air filter, serpentine belt, belt pulleys, and the cabin air filter. All told, it took me somewhere in the neighborhood of 5-6 hours to get everything swapped out.
On a scale of 1 (pleasantly smiling while working) to 10 (throwing wrenches with fervor and having my neighbors convinced I’m a psychopath), I would rate this job somewhere around a 5.
I want to take this opportunity to mention my dislike of these alleged "quick disconnect" radiator hoses. When they mount up perfectly, they work just fine, but I fought the lower radiator hose several times before I finally got it to stop leaking and driving me to madness.
When it comes to engineering cars to be serviced, ze Germans are a complicated lot. But I will say, one positive of their over-engineering is that the car actually bleeds its own cooling system! It only takes about 20 minutes, and I was like an overly fascinated child, opening the coolant reservoir housing and watching it bleed the bubbles out on its own!
Hey Stanley, Stop Stuttering:
With nearly every code in the DME eradicated, it was now time to figure out why the car was stuttering at various RPMs. From solving similar problems in other cars in the past, I’ve typically found it’s either an issue with fuel or spark. So, in typical parts-cannon excess-style thinking, I decided to go with d) All of the above.
Since the fuel gauge also wasn’t reading past 1/4 tank, I figured I’d replace the whole assembly. The thing is, there isn’t just one assembly. Those crafty Germans put two turrets in the fuel tank, one of which contains the fuel pump and the other, the filter, which seemingly has to be replaced as a full unit. Get ready to open your wallet on this one, boys—these things aren’t exactly cheap.
Removing the rear seat to access the turrets isn’t all that bad, but there’s a hose that connects the pump and filter inside the tank. I’m pretty sure that hose was designed to discourage you from touching it and to just send you to your local BMW shop. Either way, after a bit of profanity and finagling, I was able to connect the hose and button everything up without issue.
Note to self: Don’t do this (again) with a nearly full tank of fuel. Unless, of course, you enjoy soaking your arms in gasoline. In which case, YOLO. Also, pulling the hose through the tank with a piece of string (which you can pull through during removal) was a handy tip I picked up from a knowledgeable gentleman on YouTube. Kudos to that guy!
It was then time to replace the spark plugs and since the car had 133,000 miles on the clock, I threw in a set of brand new Bosch coil packs for good measure. Being an inline-6, the spark plugs weren't terribly difficult to get to after removing the engine cover and cowling.
When I finished, it was time to fire the car up... the moment of truth. I pressed the start button, and after the fuel pressurized the lines... it fired up! The misfire/stutter was completely gone! I have no idea if the problem was fuel or spark-related, as I did them both on the same day, but I didn’t really care. Mission accomplished. The N52 was now a smooth-running motor!
At this point, I figured I’d also take care of other potential maintenance problems that too much time on forums had convinced me would be problematic at some point.
I picked up a set of new OEM VANOS solenoids. My stock solenoids seemed perfectly fine, but this was yet again just for my own peace of mind and likely completely unnecessary. I swapped them out easily in just a few minutes. Finally, a "maintenance item" that was easy to access! We won’t get bogged down with the fact that this "maintenance item" was seemingly unproblematic and likely didn’t need to be done. A win is a win!
I also swapped in a new OE timing chain tensioner, which was very easy to access and install.
During this whole process, I also changed the usual suspects—namely the oil and transmission fluid—which appeared to have seen better days.
After reading the horror stories of constantly leaking BMWs, I was shocked to find my little 128i had only one leak to speak of—from the oil filler cap itself. A few bucks for a new Febi oil filler cap solved it in just a few seconds. To my astonishment, I didn’t see any signs of leaking in any of the usual suspect places—the oil pan, valve cover, and oil filter housing gaskets all looked just fine.
When everything listed above was complete, a Christmas miracle occurred: the dash was completely void of any lights!
I'm pretty sure that any time a BMW clears all of its dash lights, a German scientist somewhere gets his wings.
At this point, I had cleared nearly every code in the DME (only an automatic wiper code persisted, even though the automatic wipers worked just fine). I completely cleared all the dash lights. The motor was now running perfectly, and pretty much all major powertrain servicing had been completed. There was still the matter of the car trying to kill me if driven at anything over a crawl—minor (major?) details to be solved in a later post. For now, things were looking up.
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