Tuesday, April 3, 2012
Chuck Engine Light Reveals Cam Sensor Faults
Last night, shortly after I started the car to head home from the office, I realized that the CEL (otherwise known as the CHUCK ENGINE LIGHT) was illuminated. Rats. The vehicle seemed to run nicely all the way home so I assumed it wasn't anything critical. Still, I couldn't help but give my personal diagnostic subroutine a crack at the task. By the time I reached home I didn't have any viable theories so I decided at that point to simply get up early and take the car to my technician for access to his eons of experience and, of course, the BMW diagnostic computer.
After a brief search at the dealer this morning I found my technician hiding in the rear shop -- which I found to be refreshingly quiet as compared to the front shop -- and I only had to wait a few moments for him to finish up a phone call to solicit his assistance. While I waited I noticed an E92 coupe up on the lift with both tires on the left side of the car sporting a sizeable bubble in the sidewall. Someone had obviously hit a pothole and taken out at least $400 worth of tires (well, at dealer cost more like $600) and perhaps a couple wheels at $600 a pop. This can happen to anyone, especially as the roads deteriorate due to misappropriated budgets, but from what my technician says he sees many repeat offenders. That could be due to environment (some towns in NJ spend as little as 10% of their tax revenues on road maintenance, which I find reprehensible) or a lack of driving skill but it's probably a little of both.
When it came time to grab the diagnostic computer and probe the depths of my E36's DME for trouble codes my technician instinctually reached for the old GT1 because apparently the newer SSS still has trouble talking to the older cars, particularly with respect to its ability to reliably clear codes. "The problem", my technician recounted, "is that after you fix the problem by replacing whatever components were required, it fails to clear the codes and tricks you into thinking the problem still exists and that you have to continue troubleshooting". So new is not necessarily better. Gazing at the battle-worn wireless diagnostic head connected to my 20 pin connector I commented "man, you don't know how much I want one of those". He smirked and replied "yea, you and all the other dealers."
A couple minutes later the GT1 had successfully communicated the source of my CEL -- two cam position sensor faults, the last of which occurred about 2 hours ago (drive time). That didn't make much sense to me as I hadn't driven the car more than about 45 minutes since the CEL first appeared, but I wasn't about to question the diagnosis. My technician quickly showed me the location of the sensor I needed to replace. That rang a bell and I realized simultaneously as my technician explained the corrective action that I'd have to pull the airbox, alternator duct, vanos solenoid, and perhaps the CCV and vanos oil supply hoses out of the way to gain access to both the sensor and its electrical connector located under the intake manifold. After the GT1 predictably and quickly cleared the codes I drove over to the parts department to pick up a new sensor. I assumed that they would have to order the part but was surprised to learn that they had the part in stock so I picked it up today at a much appreciated 35% discount.
At this point I figured that I'd drive the car until I could afford the time to replace the sensor since it continued to run well. Of course, you know what they say about the best laid plans. This evening I channeled Phil Connors when I started the car to go home only to see the CHUCK ENGINE light appear again. Double rats! This time I got out to listen to the engine and exhaust only to hear a very slightly unstable idle. Since I know camshaft sensor faults can cause the engine to run rough or fail to start at all, I took this as a sign that I should bring the car to the garage and swap it for the E46, if for no other reason than to avoid the hassle and expense of a tow should the sensor decide to give up the ghost permanently.
I showed up at the garage some 30 minutes later and found my baby waiting patiently for me after months of slumber. I turned the key and she eagerly fired on the first cylinder. A quick check of the tire pressure using my recently purchased gauge revealed the need to fire up the compressor, but I made quick work of that, transferred my stuff into my new(er) chariot, and headed home. I expect to replace the sensor later this week.
Mileage: 220160, Labor Saved: $80, Parts: $105, Parts Saved: $70
Friday, April 6, 2012
New Cam Sensor Installed, or What DIY Techs Do With Time Off
After many weeks without a day off I decided to take a vacation day today. Of course, "vacation" is relative, and I always have so many projects on the burner (as well as waiting in the wings) that time off always translates into time spent doing work of another type. And today was no different, since I knew I had to replace the cam sensor in the E36 in order to return it to service. While conducting some last minute research on the task I realized that I would indeed have to remove the vanos oil line and that meant having a couple new sealing rings at the ready, so the first task of the day was a trip to the dealer to pick up those parts. I called ahead to check on stock and I was fortunate twice -- first, because they had them in stock, and second, because they put a half dozen in a bag and handed them to me free of charge. Cool, eh?
Of course, no trip to the dealer with an ailing car would be complete without a trip down the line of new cars. During my stroll I discovered a beautiful Interlagos Blue 2012 M3. As I walked around the car I contemplated the sad fact that it contains the very last normally-aspirated engine in the M line. While I have never been a fan of the E9x series of BMWs, this particular car looked amazing....right up until I got to the window sticker: $75K including dual clutch gearbox, etc. I'd buy it only as a stripper (with a 6MT) but still they're $65K in that form and that's idiotic. And it's only going to worse from here -- the new F30 3 series is $41K stripped with a 4-banger. My technician has driven it and gave the engine the thumbs up, but turbocharged or not, regardless of the specs, I'm not spending $40K+ on a 4 cylinder car. Congratulations BMW...you're doing a fine job pushing me toward that Cayman S. Keep up the good work.
Back at the garage I took my time and replaced the cam sensor in a bit over an hour. As expected I had to pull the airbox, alternator duct, oil filter, vanos oil hose, and the vanos solenoid to provide clearance to remove the sensor. Incidentally, details on how to remove the airbox, alternator duct, and oil filter may be found in my Alternator and Oil Service DIYs. Once those parts were removed I placed a clean towel over the alternator, oil filter housing and belts just to be sure that if oil did leak at any point in the process it would not make a mess on the engine or worse, contaminate the belts. A 19mm box end wrench allowed me quickly remove the hollow bolt retaining the vanos oil hose, and perhaps because I put the car to bed several days ago only a few drops of oil came out of the hose as I removed it from the fitting.
With the hose removed I was able to get my huge 32 mm wrench on the flats of the vanos solenoid case and crack it loose. As it turned out the sensor wire leading from the solenoid is only about four inches long and terminates with a connector that mates with the wiring that runs under the intake manifold. I disconnected the sensor wire at this junction and then held the connector in one hand and rotated it at the same speed I loosened the solenoid housing to prevent the wire from twisting.. Why be so careful? The insulation on the wire was slightly heat damaged and a new vanos solenoid is $200. I expect to replace it when I overhaul the engine, but wanted to avoid that expense now. The most oil I saw during the entire process came when I removed the solenoid, but that too was a miniscule amount and was easily contained when I tipped the wire-end down as it came free of the head.
I wound up using a standard 3/8" drive 5mm allen socket to remove the sensor retaining bolt. It didn't want to come out initially so I took extra care to "rock" the bolt, meaning I loosened 1/8 turn then tightened it back up, then loosened 1/4 turn and then tightened, etc. After about two cycles I squirted a couple drops of PB blaster over the gap that now appeared between the head of the bolt and the face of the head and waited a minute before continuing. That dramatically reduced the friction on the bolt and it came out quickly and easily after that. This technique is helpful on rusted or corroded fasteners and, I can now report, on fasteners laced with thread locker. Sure enough, as the bolt came out I saw the tell-tale signs of blue loctite.
After pulling the old sensor out I spent some time cleaning the threads of the sensor retaining bolt as well as the recess in the head where the sensor o-ring sits before sending the new sender home, which literally popped into place. I put a drop of fresh blue loctite on the bolt before I drove that in and torqued by feel to about 5 foot pounds. It doesn't take much. I then reinstalled the solenoid, oil line, oil filter, alternator duct, and lastly, the airbox. I turned the key to find the CEL still present which was completely expected since CELs occur because of hard faults that must be cleared with diagnostic equipment. So after a quick leak check I decided to drive over to the dealer to find my technician and have him clear the codes once again.
This time I found my technician hiding in plain sight at the back of the front shop working on a 650. When I noticed the turbocharged engine tightly packed in the engine bay I commented "well, at least you can get to all the expensive hot-section bits that fail all the time", referring of course to how BMW now puts the turbos and wastegates in the valley of the engine. Obviously speaking from experience he wearily rebutted "yea, that's true, but good luck getting at the injectors...since they're now where the exhaust headers used to be". So much for progress.
A few minutes after I told him what I needed he offered to connect the new SSS but we didn't have much luck with that. It just refused to talk to the car. So we disconnected the equipment and drove back to the rear shop where he had ready access to the same GT1 and wireless head we used earlier in the week. Naturally, the GT1 cleared the codes no muss, no fuss. Before I knew it I had said my goodbyes and was headed home with the CEL extinguished and engine running smoothly. Mission accomplished.
I didn't think to ask what book labor is on a cam sensor replacement, but I have a hard time believing the customer is charged less than 1.5 hours for this task so I'll call this $192 labor saved. Combined with the parts savings that brings the DIY dividend for this project to $262. Once again, not a bad return for a couple hours out of my day.
Reader Donation: Box Wrench Socket and Bit Adapter Set
You may recall I used an "alternative" technique to swap out my failed driver's side window motor last year. A reader recently sent me mail to comment that the tool I was looking for at the time is called a box-end wrench adapter and he offered to send me a set to thank me for the writeup. The toolset arrived in the mail this week and has been added to my ever-growing tool collection. I expect them to come in handy the next time I have to replace the window motor because I'll probably use the "alternative" technique to replace the motor even if it is still operational simply to eliminate the need to remove the regulator.
My hope is that I won't need these tools for a couple years (which seems to be about how long those stupid motors last) but I know from long experience that I *will* need them eventually. Well, unless I go do something stupid and buy a new car to replace the E36.
Naaaaa. Never happen.
Mileage: 220220, Labor Saved: $192
Friday, April 27, 2012
More Front End Parts
This month I ordered the remaining"big ticket" items needed for the front suspension overhaul including the springs, struts, and guide supports. After a lot of thought I decided to go with OE guide supports rather than aftermarket camber plates for financial and logistical reasons. With everything I have planned for the car this year I felt the money would be better spent elsewhere and I just didn't want to deal with any fitment or noise issues that might come up with the plates while the car is a daily driver.
For some reason I seem to recall that the original guide supports for the E36 were stamped out of steel but that may just be my imagination. In any case the new parts I received are made of aluminum and appear quite similar to what I've seen on the newer cars. Toward that end they come with an alignment dowel installed (see picture). The dowel is screwed into the base and thus easily removed for the E36 application.
I also managed to pick up the M3 strut tower reinforcements because the roads in New Jersey continue to deteriorate and I want to minimize the chance of any deformation or ballooning of the strut towers. As it turns out these are made out of some surprisingly thick steel -- I didn't have my digital calipers handy but I beileve it to be 1.5 mm or about 16 gauge. The strength is bolstered by roughly 5mm long flanges bent on both the inner and outer diameters. Use of the reinforcements will naturally raise the front end by a hair but I think it's fair to say that the effect will be minimal.
The last thing on the order was a pack of four bolts required to reattach the subframe to the vehicle. The TIS shows two torque specifications:
- E36: M12 12.9 bolt, 105 Nm
- E36/E46: M12 10.9 bolt, 110 Nm (Not labeled as such, but I presume this applies to E36 M cars and possibly the convertible)
Neither specification includes an torque angle yet the TIS does require replacement of the bolts. So those values are sufficient to bring the bolts beyond their yield point, or the point at which permanent stretch occurs. During my research I discovered many people advocating the use of star washers with these bolts. Again according to the TIS that only applies to "Up to model year 1993". "Since 1993", the holes in the frame were tapered and the star washers were removed from the assembly process. Both torque specifications are with threads dry and that precludes the use of thread-locker or even anti-seize as others have incorrectly advocated. To summarize, the bolts are installed dry and torqued to 105 Nm. That's it.
The few remaining items I need to start the work include:
- Lower steering column parts
- Fender liners
- ABS/Brake Sensor junction boxes
- Debris guards ("pork chops") or aluminum panel
- Nutserts and Installation Tool
If you're wondering why I'm doing the fender liners it's not for cosmetics though I'm sure they'll polish off the project quite nicely. Rather, I have to replace them because they provide a couple mounting points for the "pork chops" that long ago broke off. I guess they don't respond well to the shock of deer bouncing off the front bumper. Whooda thunk it?
I am also considering the installation of a metal underpanel which would eliminate the pork chops entirely, provide additional protection for the radiator/condensor assembly and streamline the airflow to boot, but I'll have to do some additional research first to figure out if there are any reasonably-priced parts available.
The month of May will likely be quite busy for me so my guess right now is that I will start work in June sometime.
Mileage: 221200, Parts: $950