Mountains

Mountains

Thursday, December 31, 2015

Friday, December 18, 2015

In Memory of Leaves



It was a long autumn that I missed completely, only getting to experience it teetering on the doorstep or sprawled on the couch. Will have to try again next year.

Wednesday, December 9, 2015

Need more Crass Bypass Gas: Iron Duke EGR Valve Swap

Or

The ChevOldsmobuiac's EGR valve finally died in a way that surprised me.

The majority of the A-body oldsmobile cutlass cieras on the road are demotivated by 4-cylinder Iron Duke engines.  The upshot is that the engine is shared with many other GM vehicles, including the S-10, Fiero, and of course, the Grumman LLV that your postman probably dreads driving at work every day, so there is a lot of information available about the care, feeding, and repair of the powerplant, even though there are many production line tweaks that can make swapping major components (heads chief among them) difficult if researched first.

The Haynes manual notes that the EGR Valves tend get carboned up and sieze. Part of my regular maintenance has been depressing the diaphram to ensure that the valve could actuate.
 
A few months ago, the Check Engine light started coming on after the engine warmed up (it seemed like after 15-30 minutes of operation... I could almost pick the intersection after a week of commuting), after the light went on, the engine would noticeably ping/rattle under moderate acceleration. While I initially suspected another faulty ECM module, reading the codes yielded a consistent bad EGR valve code (Code 44 also for lean exhaust).




Low and behold, with the engine at idle, the valve was fully closed, as could be felt on the back of the diaphram with engine air filter off.

Of note, the EGR valve on this car is completely mechanical: it is connected directly to the intake manifold and it is regulated by a pinhole orifice on the EGR valve body. It slowly opens and closes as engine vacuum changes: under idle, moderate accelleration, and coast, it is open. Under heavy load, it closes.


Detailed photos of the new valve:
The diaphram appears to be a silicone membrane.

Pinhole that regulates gas flow to the intake manifold.

Serial Number.

Exhaust goes into the round orifice and out the square one.

Closed position.

Open position. When you open the valve, the cover the vacuum nipple, it should stay open. Otherwise, there's a leak in the diaphragm.

The box it came in. Recognize the part number?

Old EGR valve exposed under the air filter snorkel. I should have covered the TBI, but I was on crutches with I did this operation, and wasn't interested in making a lot of trips.

Old EGR Valve. Interesting: Old part number does not match the new one. Hope this works.

Carboned up old valve.

I'm totally guilty of smearing a bit of antisieze on the port the last time I took off the EGR valve, because it was corroded on pretty well.

 Vacuum test the new valve one more time. It's kind fun, after all.

Side by comparison. Note: Hecho en Chine. I feel a little bad for whoever made the new valve, since they will probably never see any car that it is designed for. Then again, maybe I should feel happy for them, since all the cars they will see were made in this century.

Bottoms looks pretty similiar. Gasket is stuck on the old valve.


The swap was pretty trivial. It took about 10 minutes with a couple of different 13 mm wrenches to reach under the diaphram and navigate all the hardware on the top of the engine. I highly recommend a deep-offset 12 point, 13-mm wrench for this job. A flex head ratcheting gear wrench might also work, but I didn't have one to test. For completely visible bolts, they were awfully obscured.  With plain wrenches, you might have to disconnect the throttle cables to get enough swing to get the bolts out. This is not a good party for your socket set.

While you're at it, I suggest replacing the now very rusty bolts with new ones and putting a dab of antisieze on them. What possesses car makers to put iron bolts in aluminium parts is beyond me, and is certainly a sign that large portions of our engineering population failed basic chemistry.

In the end, the engine appears to be a lot happier. For a long time there's been a lingering burble/valve rattle sound that I now realize must of been pinging due to lean mixture. That sound is now completely gone. This engine does not have a ping detector, so this might be worth looking at if you have mysterious pinging. The EGR valve had to be very dead for the computer to turn on the check engine light.

Another note is that this probably means that you can't put a plate over the EGR valve on fuel injected engines without remapping the ECU to accept and adjust the mixture. I'm not sure how exactly the car knows the exhaust gas is missing from the mixture, but I'll be it has to do with a combination of manifold pressure and the position of the idle air control valve. Long story short: unless you know how to remap an ECU, getting a blockoff plate will not help you on the TBI engines. Since my EGR was failed in the closed position, it was functionally the same as a block off, and the computer remained unhappy and drivability was compromised by excess pinging.







Auto Parts Epiphany

I'm beginning to think, nay, truely believe, that most replacement car parts, even OEM replacement parts, are inferior to the components originally installed on the car.

The immediate case in point is the parking brake cables on the ChevOldsmoBuiac, my 1990 GM a-body oldsmobile. The original cable worked perfectly for 20 years, though it eventually seized, piece by piece (it has 3 sections), over the past 5. A few years ago I replaced the last piece and thought I was good forever.

These cables seize because the outer sheathing coils rust and expand, constricting the nylon coated inside. The new cables apparently had inferior environmental protection, and so now have suddenly decided that they can barely budge.

Similiarly, the original brake cylinders (rear) and brake calipers (front) have required periodic replacement due to leaks and seizing every few years since the originals were replaced in 2007 or so. If memory serves, we're on the third set.

We also blow through rear pipes and mufflers at a rate of one ever 3 years. It's kinda nuts.

Far cheaper than a car payment, since I'm doing the work, but still kinda nuts.

I don't think this holds across the board, of course, I swapped the OEM shocks and struts in the Olds for Monroes in 2005 and they've been great. I only am thinking about replacing them now due to dry rotting bushings and the impressive amount of rust present.

Perhaps a descerning shade tree mechanic would do well to attempt to source and install only premium parts.

Except I mostly do that, and it doesn't seem to help.

Robot Design Fundamentals


Saturday, November 28, 2015

Lenovo x120e 802.11n Wireless Data Corruption with RTL 8188CE 1x1 NIC

I've known that this wireless card was toxic for a long while.

However, laziness has meant that our household has been trapped in 802.11g land for years and years, even as I gave 802.11ac routers to family members as gifts.

Because the shoemakers children have no shoes or something.

Anyhow, I knew the Thinkpads* Realtek RTL 8188CE wireless card was bad news when the other machines started experiencing network instability whenever it was active on the network. The wifes Netflix stream would glitch. Copying files requires 100% of the CPU, and similarly, network intensive multiplayer games took it in the chin as the CPU was soaked by the NIC, detracting from rendering.

But, I recently got the joy of trying out one of the 802.11ac routers that I had been gifting (Asus rt-ac68u), and was pleasantly surprised by the speed (the adapter reported speed of up to 150 mbps) and unpleasantly surprised by how all the data that came through the pipe was more or less ruined by the experience. Installers claimed checkup errors, binaries wouldn't run right, and webpages and other internet content looked a little...weird.

An example corrupted page from this blog

The network interface showed itself as a possible candidate when other machines in the house didn't have the same issues, and I found that downloading the same file several times yielded different checksums each time. I was particularly ticked off when my linux virtualmachine a) had trouble getting updates b) once updated couldn't stay booted for long, presumably because of data transfer errors. At first, I thought this was due to an old version of virtualbox, but then when I tried to update virtualbox, it complained of .cab checksum errors. Running hashmyfiles on windows 7 showed that each time the virtualbox installer was downloaded, I got a different checksum. Of course, I was suspicious of that too, but it was all I had to work with.

Crazy.

Sadly, There is little information avaiable about this situation and what can be done about it. After a day of fiddling, I determined that the RTL 8188CE can be forced into 802.11g or 802.11b mode, which home use had more-or-less shown to be less error prone. To force 802.11b or 802.11g, activate Taskbar->Wireless Icon->(Your Wireless Network)->Status->Properties->Configure->Advanced->Wireless Mode->802.11b/g (or 802.11b). Setting "Auto" will allow 802.11n, and thus data corruption, at least in my usage scenario. Corruption was greatly reduced (i.e. I could download files and view websites normally) with 802.11g forced (by selecting 802.11b/g mode).

I had read in a few places references to errors generated by the TCP/IP checksum offloading feature of the card, though it seems possible that the checksum maybe fine and in fact the card is not moving data correctly.

Things to meditate on:
1) Checksum are valuable to making sure data makes it from point a to point b without getting fubared.
2) All the advice about hacking the bios to remove the pcie whitelist to allow other mini pcie NICs is probably well founded.
3) The RTL 8188CE is just painful on this machine. Neither realtek nor lenovo have fixed the drivers, and data corruption is evil. I have to ask myself if other issues i'm experiencing on the machine are a product of running windows update through a leaky wireless pipe.
4) Curiously, the RTL 8188CE is not mentioned in the list of 802.11n adapters provided by Lenovo, but Broadcom 43225 and Intel 6200 (6250 as well) are. They would seem like rational upgrades.
5) The 2x2 abgn adapter chipset/part number relationships reported online are all over the map. The Lenovo FRU 60Y3253 corresponds to both Intel and Broadcom chips.

*More like Stinkpad amiright?