Nemo Re-Assembled

I think this will be a quick post. In my last, rather lengthy, post about Nemo, I described the effort to get him running again. Today, I cover the electrical mop-up and the other little bits to get Nemo ready for regular use... by someone. While this is barely post-worthy, the wiring fix did take me a few hours, so in a way this is just documenting how I spent a Saturday. Besides, the weather has turned too cold to spray primer or paint, so Zed sits waiting.

Car-Toys Vent

I will start with a predictable slam on the hacks at Car Toys. Recall that when they replaced Nemo's stereo, they were directly asked/told not to cut up the wiring, rather to use a pigtail. With a generic response of along the lines of "we'll do it right" wink/finger-point, they did exactly what no one wants a radio installer to do: cut wires off of a harness plug and then direct-wire a new stereo into those bare wires. So, I give them a "that's not right" glower/different-finger-gesture. All-told, they cut the 8 speaker wires, switched and steady power, ground, power antennae and illumination. The part I don't understand is why they do not have a cache of pigtails for common cars. All VW's and Audi's from, like, the mid-80's thru modern cars use the same 2 8-pin female plugs... one 8-pin plug for the speakers and one 8-pin plug for the power, illumination, etc. The corresponding male pigtails run for, like $10US on eBay, and since they plug right in, the install is faster, while also cleaner: at a workbench, the custom pigtail for the new stereo can be wired into the Audi/VW standard male pigtails. Then, you take the stereo head-unit and the cable to the car, plug in each end and you're done. Cleaner, easier, faster. Instead, Car Toys does it lazier, longer, stupider and uglier... and much harder to undo.

Stereo Wiring Un-Hack

With the center console fully opened up, I had great access to the great wire hack. I started with the speaker wires, mostly because bits of the CarToys wire-extensions (1 each purple, grey and green) were still attached to a few wires post-theft, so I could tell what they used to be used for. Once those 8 wires were sorted, the remaining wires were much easier to isolate. The only difficult pair were the switched and steady power sources, because both were plain red wires. A simple voltage test (one had 12V and one didn't while at rest) resolved that. Yes, there was a hot wire bouncing around back there. Once the pigtails were wired up, I zip tied the wires into a cable on either side of the wire butt-joints so any gentle pulling would not cause a wire joint to separate.

Climate Control and Console Re-Assembly

With the loose wires sorted, the center console already looked 100% better. I continued the re-assembly by plugging in the climate control unit. While this has 4 plugs, they are each slightly different sizes so they can only go in one way. Once plugged in, I slid the unit into place and threaded in the Torx bolts to hold it in. Then, the console cover can snap into place. 2 8mm Allen head screws later, the center console is together again. I take satisfaction in seeing the stereo plug through the hole where a stereo should be. I may pick up a cheapy clearance stereo from Crutchfield to completely close the loop... and that hole.

Kick Panel and Re-Lo

All that remained was putting the lower dash panel back on. This panel is held in place by 3 screws: one at the bottom of the fuse box frame and 2 in front of each of the driver's knees. The fuse box frame screw is easy to get to and easy to manage. The 2 in front of the driver's knees, however, require some gravity-defying. I do not know what kind of fastener was originally used; Nemo has slotted bolts. These bolts need to be balanced on the end of the driver and then tilted over about 30* to find the hole in the panel, and then the matching hole in the dash. While this is not hard, it can be frustrating. Once bolted tight, the holes are covered with small plastic bits that snap into place.

Just like that, an interior that looked like it was at a junk yard is re-assembled and looking sharp again. I juggled cars at this point, moving Nemo into a more remote spot, out from under the carport. As before, he started right up like he hadn't been un-start-able for weeks. The juggle created the space needed to get Oliver out for some Summer driving. I did discover, however, that Nemo's front passenger window I replaced also had the front window tracking mechanism damaged when the window was smashed in. So, the window does not go up and down anymore. I will need to hit the junk yard again, to source a replacement window track thing. Neat. I do like going to the junk yard, though, so maybe I'll find some other stuff we need while I'm there. In the meantime, Nemo's air conditioning blows nice and cold, so a stuck window doesn't mean discomfort.

That's it for today. Thanks, as always, for following along-

MGB - Finding Vacuum Leak

Following my last post about Oliver (the 1978 MGB) when I got his timing square, I knew I needed to get his carb tuned. Today's post covers those efforts. This continued in parallel with the body work on Zed (until the weather turned, when Zed work stopped). These spring days, when the sun doesn't go down until 9PM creates LOTS of play-on-cars time. Love it.

A-typical Carb

We start with the most basic learning: what kind of carb is this? When I bought this car, the prior owner had been executing some improvements. For the most part, I can't complain about any of them... except the hack-job on the exhaust. Honestly, he could have been just making do until he had the cabbage to do what I did. Anyway, one of the improvements was to eliminate the stock dual Skinner Union (SU) carbs and swap in a side-draft carb. This isn't your standard Weber DCOE, though. Instead, the prior owner went with a SK Racing carb. The SK Racing (now known as OER Racing) side draft carb was (according to Dog283) one of the best engineered side draft carbs built, just as carburetors were falling out of favor for the new computer-assisted fuel injection systems. Dog283 continued "(the SKRacing side draft) combine(s) the best of the the Mikuni Solex PHH, the Weber DCOE and the Dellorto DHLA". That's a fairly strong statement. Unfortunately, the implementation on Oliver had fallen out of tune, so our MGB was not getting the lofty results this statement describes.

We start with looking for, and ultimately finding, a shop manual for the SK Racing side draft carb. If you have one of these carbs and need a copy of this manual, I'll happily share it. Near the back of it are the set-up steps detailed in the image of the page on the right. Basically, set the idle speed screw so it is just barely touching the tang, thread the idle adjustment screws all the way in until they just barely seat and then rotate them back out 1 full turn. Start the engine and get it to normal operating temperature. Then, tune the adjustment screws first until the engine runs smoothly, then set the idle speed. I did that, but I still got sporadic backfires when I rev'd the engine. I was starting to think that all that ignition work was for nothing.

Exhaust Leak Checks

Before I started investing time in the carb, I figured it would be a good idea to see if there were any leaks in my exhaust which could account for the backfiring. There were. To test, I started by cleaning out my shop-vac (washed out with a hose) and grabbing a squirt bottle of soapy water. I thrust the exhaust end of my now-clean shop-vac up the tail pipe and turned it on. This created backpressure through the exhaust. The tail pipe was not completely blocked so lots of air rushed right back out, but there was enough pressure to execute my test. I started up front, in the engine compartment and shot soapy water on the mate-point between the header and the head. No bubbles. I then got under the car and hit every joint, and found some bubbles. I concluded that I created leaks when I added in the catalytic converter. I turned off the shop-vac, loosened the joints, slid the pipes apart and applied some copper exhaust gasket maker and then re-connected the pipes. I nutted them back down and re-checked with the shop-vac. Things looked fixed (no bubbles at all but one joint where there were very very few), so I moved on to tuning, expecting my backfire issues had been identified and resolved.

Gunson ColorTune

Back when I was doing the other work on Oliver, I kind of expected difficulty with getting the carb to adjust. So, before I finished getting the ignition installed, I ordered a Gunson ColorTune. These things are pretty neat, but not terribly useful, I suspect, for the computer-controlled fuel injected systems. The kit includes a looking-glass spark plug, a lead, a tube with a mirror and a brush. I only needed the glass spark plug and the lead. The looking-glass has a solid-center where the spark is produced, with a ring of glass around it. The glass ring is then encircled with threaded metal so it can be threaded into an engine. The tube with a mirror is for spark plug holes that are hard to see. To use the kit, you remove one spark plug and thread the looking-glass plug in it's place. You connect the spark plug lead to the end of the lead from the kit, which is threaded onto the glass plug. Then, you start the engine and look at the color of the combustion in the chamber through the glass. If the color is orange or red, your mixture is too rich. You want the color to be "Bunson blue" = the color of a Bunson burner, from, like science class. The images on the right, here, help lead you to a good tuning. Notice that light blue or white-ish is not on here. If you are in the white-zone (Airplane, the movie reference here), your tune is too lean.

I was unable to get cylinders 1 and 2 anything better than a very light blue even after adjusting the idle mixture out past 1-1/2 turns. Cylinders 3/4 did not do much better. Based on the manual, I believe the idle jets may be too small, so I ordered a pair of 50F9 jets ($7US each). If I am correct, the current idle jets are 45's and this change will allow idle-mixture within 1-1/2 turns of fully seated to sit in the Bunson-blue color.

Still, I kept going, wanting to get the tune as good as I could. While looking through the glass I increased the fuel mixture incrementally, but the misses and backfires persisted. I could see the backfiring through the glass in cylinder 1, and concluded there had to be a leak somewhere. I also figured that backfires within a cylinder that has a glass plug was probably not a good idea. I had already looked on the exhaust side for leaks, so that left the intake.

Intake Vacuum Leak Checks

There are not many places where a leak could appear in the intake: the mating point at the head, the mating point with the carb, the carb itself and the brake booster. With the engine running, I carefully sprayed some WD-40 onto the various mate points. If there had been a vacuum leak, the vapor would have been drawn into the engine and the RPM would have bumped in response. Spraying something flammable onto a hot engine is dangerous. I strongly urge you to keep a fire extinguisher handy if you do this. In my case, the engine did not change and nothing caught fire.

So, I shut everything off and considered the brake booster. I removed the hose from the check valve, which is threaded into the intake manifold heading to cylinders 1 and 2. I checked the vacuum of the brake booster through that hose with the MityVac. It would not hold vacuum. I removed the check valve and cleaned the valve and the intake manifold where they met. Then, I put some copper gasket maker on the threads of the check valve and threaded it back in. I figured if that was the leak, I just solved it. I jabbed the hose back onto the check valve and hose-clamped it tight. Then, I eliminated the brake booster by threading a bolt into the end of the hose which had previously been attached to the booster, and started the engine. Oliver ran great! I could rev him up and down without any backfires demonstrating that the brake booster was my vacuum leak.

check valve in foreground,
intake in background

I wanted to prove it for sure, so I hooked the booster hose back up to the brake booster and started the engine again. I rev'd the engine up and down... the back fired returned. I pinched the vacuum hose with a pair of pliers and I could hear the engine RPM's settle. Neat. Rev rev rev... no back fires. Remove the pliers, RPM increases... rev, rev, rev... backfires.

Fortunately, these brake boosters are being manufactured now. I didn't realize these were not available until recently, so as much as I would like to self-blame for not replacing the booster when I replaced the brake and clutch master cylinders, it wasn't available then and they are fairly expensive now (~$200US). As of today, they are not available through Moss yet. I had to go through another vendor (EnglishParts.com, they're lovely). I concluded that any carb tuning I had done would need to be redone once the brake booster swap was completed. 

That's it for today. I will install and post about the brake booster when it arrives from the MidWest. Thanks, as always, for following along-

Oh, Nemo

Today's post covers my challenges with Nemo's electrical and computer system simply trying to get him to start, or maybe a signal on the OBD-2 port. The car-work hours that I did not want to spend sanding on Zed, I spent doing this... until this took over. Yeah, I know. I could use another hobby.

No Start

Like so many issues with these old cars, our challenges with Nemo started with him not starting. His battery had been sitting on a trickle charger all winter, but I had left his hood cracked to make room for the alligator clips, so this ultimately was self-inflicted. Love those. But, the path we took to get there was interesting. Nemo is sitting under the fabric carport blocking a garage door. Behind that garage door sits Oliver, the 1978 MGB convertible, that I would very much like to be road testing and otherwise driving around. So, enter my motivation for moving Nemo. Insert key, turn ignition to "RUN". I see some familiar idiot lights, including the battery, oil and check-engine. Turn to "START" and he rev'd but would not start. I went around to the tailpipe and could not smell gas, so I start with the assumption that it is fuel delivery.

Before I did anything else, I considered what I experienced when I turned the key to "RUN". I did not hear the fuel pump cycle. I did not hear the radiator fans kick on. So, something is not getting the "RUN" signal. So, I pull out the UltraGauge and plug it into the OBD-2 port. I get a never-ending "scanning..." message. Well, that's not good. I double-checked the UltraGauge in Hapy, and the computer linked within a few seconds. Okay, we have trouble with Nemo's diagnostic system which could prevent a start or we have multiple things going on. With this car, the latter is probably true. First, I tried to isolate the OBD-2 issue, and kill many many hours doing so.

OBD-2 Issue Diagnosis: General

The early B5 versions of the A4 had some interesting 1 or 2 year only issues. One of the oddities around 1997, when Nemo was sold, was the engineers choice to integrate the stock stereo with the "K-line": the signal processing wiring between the computer, many components and the OBD-2 plug. In these late 90's cars, it is the K-line you are subscribing to, not the more modern "CAN BUS". Okay, cool. There are many modules plugged into the K-line, but they are all in parallel. the diagnosis theory goes that when you get no signal on the K-line it is because one of the modules is faulting out, grounding the K-line. Once you can identify and remove the faulty module, you will get a signal on the K-line. You will probably get a failure code for that module, but you will at least get a signal. So, away we go, trying to figure out what modules are even on the K-line, and then isolating them.

OBD-2 Issue Diagnosis: Radio

The stock radio wiring was unceremoniously cut to pieces by the idiots at Car Toys when they installed an aftermarket stereo. Based on the wiring diagrams I have found and the commentary on the interwebs, I am not sure this car actually had that K-line-in-the-stereo thing. I did check the wires for the right color combinations, and for wires that were the correct colors for the K-line. I was unable to find them. There are, however, many wires sticking out of the hole where the radio used to be... before it was ripped off in Eugene. I intend to re-integrate an original plug before I put all this back together, but that's another day. I moved on to the next possible culprit: the climate control system.

OBD-2 Issue Diagnosis: Climate Control

found in climate
computer

The climate control system in these cars is another little computer. In some models, it is held in place with a couple brass clips. In Nemo, I had to remove the center console cover plate / face and found 2 Phillips screws holding it in. Once threaded out, the unit removes through the front. I unplugged the unit and checked the OBD-2 for a signal. Nope. I did, however, find a soda/beer can pull tab inside it (picture on the right, here, laying on the carpet after I removed it from inside the climate control computer thing). So, that was interesting. Next.

OBD-2 Issue Diagnosis: ABS (Brakes)

The fine folks on the interwebs have found that the ABS sometimes causes K-Line problems. The way to identify if it is the problem is to disconnect the plug. The ABS unit is on the driver (left) side, next to the washer bottle. You simply pull up on the silver metal tab and the plug lifts out of the socket. I found a piece of electrical tape floating around in there. Another question-mark from the prior owner. Neat. I checked the OBD-2 for a signal. Nope. I shot the socket and the plug with DeOxit and left it disconnected for the rest of my tests. I figured I might as well leave it better than it was (DeOxit, not leaving it unplugged). Next!

OBD-2 Issue Diagnosis: Dash Cluster

Moving on, we consider the dash cluster. The entire thing is held in by 2 Torx-head screws from the front, hidden behind a cover plate just above the steering wheel. Pull the cover plate, remove the screws and it pops right out. I unplugged the various cable plugs and checked the OBD-2 again. Nope. Grr... Next!!

OBD-2 Issue Diagnosis: ECU

example A4 ECU 

It seems like every system on the engine that has more than one wire into it delivers some signal to the computer. So, this seemed like the next logical step. I figured if I could get a signal after unplugging the small plug on the ECU, I would have shown that the issue is in the engine compartment and I could put everything in the cabin back together again. If the issue remains, then it could be the ECU. So, I disconnected the small plug from the ECU and we still didn't have a K-line signal. Grr...

So, I plugged the ECU, ABS and the dash cluster back in, turned the key to RUN and heard the click-snap of some relays firing, but no fuel pump nor fan spin. I could not remember if I heard the relays before, but this changed my thinking. If at least some of the relays are firing, then the ECU is telling them to. If there is a Check Engine Light, then the ECU must be at least partially working. Perhaps the K-line / OBD-2 issue is completely unrelated and this is just a simple fuel supply issue. So.. new plan: get the fuel pump to fire.

Fuel Pump Test

As is so often the case in laboratory settings, the pre-work for the experiment is where all the time is taken. Such is the case here. I started by removing the plate covering the fuel pump. This sits behind the rear seat in the trunk on the passenger (right) side, and is held in place with 3 very short Phillips screws. Once the plate is removed, you can see the top of the fuel pump. There are 2 fuel lines, one supply and one return, and a single electric plug. I found that slightly wiggling the plug allowed it to pull off the pump. YMMV. Once removed, you will see 4 pins. 2 of them are for the fuel level and 2 are for the pump. I started my tests with basic resistance and continuity-to-ground. Things seemed fine, so I shifted focus to test-firing the pump by applying 12V to the pump.

This is where the experiment set up took some time relative to the actual test execution. I ran a pair of wires from near the battery (not hooked up) back to the fuel pump. At the battery, I taped 10A fuse to the "red" wire and alligator-clipped the other side of the blade to the positive battery post. I alligator-clipped the "black" wire to the negative post. Back at the fuel pump, I applied the red and black wires to the fuel pump and it fired right up. I held the wires there a few second to demonstrate that it would not just run for a second and die. So, we have a good pump, but the pump won't fire from a relay signal. So, next we check the voltage from the relay, after we put the experiment wiring away.

Fuel Pump Relay Test

A4 Fuel Pump Relay

Back up front, I took a red wire, stuck it into the voltage-supply pin in the wiring plug at the fuel pump and tossed the other end through the cabin, over the outer edge of the driver seat. My plan was to compare the voltage sent to the pump at the pump. Since the relay only pops for a second when you turn on the ignition, I had to have my test equipment near the ignition key. I stuck my black lead against the metal fuse box mount, held the red lead against the wire I tossed through and turned the ignition to "RUN". I got 5V. I checked other spots around the fuse box and got 13V, so I started thinking that the relay was bad, dropping the voltage from 12/13V to 5V which, of course, is not enough to run the pump. So, I swapped out the relay... and the fuel pump still would not run. Great. I concluded that the 5V I read was actually the base charge for the fuel level sender and not the supply for running the pump. 

So, I checked the voltage at the supply-side of the relay: 13V. I jumpered across the relay pins, and the pump fired up. So, we're back to the ECU is not sending a signal. Fearing it is the ECU, I went looking for any other reason. I recalled that when Dot (the white 2000 VW Jetta 2.0 which broke the timing belt) failed, one of the theories for not starting was a crank position sensor. The thinking is that if the ECU doesn't know where in the revolution the crank is, it doesn't know when to fire, so it doesn't try. It is not as clear whether a failing crank sensor would prevent the fuel pump relay from getting a signal from the ECU, however. As much as I have tried to avoid it, it felt like I was sliding into just-swap-parts problem solving. At $35US for the least expensive part-to-swap (crank position sensors start closer to $60US), this can get needlessly expensive very quickly.

Crank Position Sensor (CKP)

A4 Crank Position Sensor

I have mentioned before my belief that the Audi engineers are sadists. Only someone who takes pleasure in other's pain could arrange for replacement items to be so hard to get to. Case-in-point: the crank position sensor. The crank runs the length of the block (obviously), so given a blank canvas, an engineer could potentially place a sensor anywhere along that axis. Chosen location? Directly under/behind the oil filter so you either have to remove the oil filter (forcing an oil change, which arguably is due) OR you need to perform contortions to get an Allen-head wrench in there. If you go this route, consider that the further the bolt comes out, the closer you get to the oil filter. At least there is only one fastener. These sensors have a long lead on them that plugs into the engine harness... behind the coolant bottle. In Nemo's case, this plug was fairly easy to get to. There are methods for testing the sensor, of course.

The Audi/VW sensor has 3 wires, from pin 1-3: power | signal | ground where the power and signal connect to the ECU and the ground finds its way to the chassis. To test, 12V and ground need to be supplied to the sensor plug (once disconnected from the harness) and a multimeter checking the signal wire for an AC wave signal while the engine is turning. No signal = bad sensor. Since no local shops had a CKP, I returned to sanding Bondo in Zed while I waited for the part to arrive.

Once I had the part in hand, I checked the resistance between the pins. I got 500ohms +/- between the middle pin and one of the outer pins. Using that as a baseline, I swapped out the CKP and then tested the one I had just removed. Same resistance. So, I concluded there was nothing wrong with the old one and put it in the stash of A4 spare parts (with the fuel pump relay).

ECU Swap

At this point, I had run completely out of ideas fo4r why the ECU was not sending a "go" signal to the fuel pump relay. I hit the local junkyard looking for a just-dropped-off A4 to scavenge the ECU. None of the A4's there had the right ECU, but I did get an ECU box cover: Nemo's had a good-sized hole in it where I thought water might have entered. Without another option, I hit eBarf and found an ECU with the same part number as the one as was currently in Nemo at a salvage yard on the East Coast (with a 30 day return policy!). Hopeful, I swapped out the ECU's which consisted of pulling out the big plugs in the back of the old and plugging them into the new one, since the box was still lid-less. I had some concern that energizing the ECU could fry it if the underlying condition still existed.

Still, I turned the key to "RUN" anyway... and heard the radiator fans and fuel pump cycle for a second before shutting off. This was how things used to work. So, I turned to start and he fired right up. I have concluded that my first guess was the correct one: I had left the hood open a little bit to make room for the alligator clips on the trickle charger, and with the hole in the ECU box lid, water got into the ECU and partly fried it. If I had not had the experience with the chipped ECU for Hapy when the computer semi-worked, I would not have been so quick to accept this. The Check Engine Light lit, so the A4 chat-boards all assume that means the ECU is fine. NOT TRUE. It could be partly damaged, like Nemo's.

The climate control is still in pieces, the lower dash panel is off, and the radio wiring, well, it's the same as it was: a mess. While I can move Nemo out of the way so Oliver can go for a spin, Nemo is not ready for driving around just yet. The re-assembly will wait, and I'll probably post on at least the re-wiring of the stereo plugs that the idiots at CarToys cut apart. I did, however, install the ECU box lid, complete with threading in the screws to hold it tightly shut. No more water getting in there.

Thanks, as always, for following along-