Category Archives: MegaSquirt EFI

Sunday Night Analysis

At the time of this writing, the engine idles pretty much flawlessly and tweaking some cells in the VE Table improved reving somewhat before I fumbled. Don’t ask me how, but I loaded and burned a previously saved msq file when I was switching back and forth between MegaTune and TunerStudioMS. I had done that a few times earlier, but I must have clicked ‘Yes’ to the question. At least it’s not like starting COMPLETELY over.

There are a couple of things going on that do not seem right. Most troubling is very flakey signals from the O2 sensor. It mostly stays pegged at 5 volts (or AFR 21.9, depending on which gauge you’re looking at), but will occasionally scatter like a crazy monkey. It was working well earlier in the day, at least returning believable numbers. Wiring looks good. I will try to locate or replace the programming cable and verify that the LC-1 is programmed correctly.

With essentially no O2 sensor, I’m tuning kinda blind and my nose says it’s rich at idle and my ears say that it leans out around 4000 RPM. Right before I shut down for the evening, I made a log file of a short run.

The first thing that was less obvious in MegaTune is a pulsing 5 KPa swing in Map at idle. This pulse occurs 6 or 7 times in most logged seconds, which corresponds with the expected vacuum pulses at idle. My vacuum signal is from one TB, which feeds two cylinders. (850 rpm / 2 cylinders) / 60 seconds per minute = 7 pulses per second. I recall a mention of such pulsing making tuning difficult and a damper made by restricting the vacuum signal slightly and following the restriction with some kind of accumulator, such as a clean, dry fuel filter. I will implement such an accumulator.

In the mean time, I will continue analysing the log file.

In a more entertaining note, it’s interesting to see single isolated MAP readings of 159 or so, which I presume correspond to backfires. Early in the first start process, when it was beginning to have a useful amount of fuel but was still too lean to run, I had a few spectacular backfires. One of them actually popped one side of the throttle body out of its rubber boot!

It Runs! Or at least it Starts and Idles!

The starter was definitely going. I pulled it out and found bronze colored flakes from where the motor shaft had been chewing on the bushing and an elongated center hole in the bushing to match.

For the non-VW people reading this, the aircooled VW uses a smallish starter motor with a shaft that engages a bushing in the transaxle case. I don’t personally know if any other vehicles do this, but it is unique in my limited experience.

It is also logical. The starter itself does not have to be as large as the usual starter with this shaft support built in, so the entire assembly is more compact.

So, my starter woes were just beginning because this transaxle used to be on a 6 volt Beetle. In 1967 when the line was converted to 12V, one of the major modifications was in the starter setup. The 12V flywheel has a few extra teeth, so it’s a little larger in diameter. The starter pinion gear is smaller (fewer teeth, with a side benefit of more mechanical advantage) and with the smaller pinion comes a smaller motor shaft and smaller bushing. I knew the transaxle had been from a 6V because of the other modifications needed to make room for the bigger 12V flywheel, but I did not yet know about the bushing change.

The easiest way around this problem is to use a starter from an automatic transmission, which for what I presume are other reasons, does not use the shaft support bushing at all.

However, AutoZone did not stock it and I didn’t want to wait for them to order it in (I need a starter NOW!) so I took a standard 12V starter. When I got home, I verified my concerns about the bushing, but I pulled the old one out anyway. Oh, and I discovered during the photo hunt above that they make a tool for pulling this bushing non-destructively. I don’t have one, so I use an adequately large tap threaded into the bushing. The end of the tap presses against the engine case and the threading action pulls the bushing out. Thanks to Ricky of the BTW for supplying this excellent tip. Of course, once the bushing was out, my bushing size fears were confirmed. I did a little more searching and found a starter for an automatic at an O’Reilly a little distance across town.

It is a substantially larger starter, but it fits and spins the engine WAY better than the old one, pretty much confirming my theory that the battery is probably OK.

In searching for the images of the starters above, I also discovered that there are plenty of vendors that supply a bushing properly sized to run a 12 volt starter in a 6 volt transaxle. They tend to run about $3, so it would be a good thing for me to have a couple of, maybe even zip tied to the starter in case I have to replace one on the road and cant get a starter for an automatic.

I was able to crank the engine enough to get it started and idling before the new starter (rebuilt, actually) developed a flakey solenoid. I was generally able to work around it with the following procedure:

1. Make parameter change that kills the engine.
2. Emit expletive
3. Restore parameter
4. Press and hold remote starter button.
5. Whack on starter solenoid with deadblow hammer until it cranks.
6. Repeat. A lot.

Before I shut out the lights last night, I pulled the starter out and will return it for replacement today. The deadblow hammer ensured that there are no overt signs of any starter abuse.

As for the *actual* process of getting the engine to start, I had a curious symptom. The calculator in MegaTune suggests a ReqFuel setting of 13.6, derived from plugging in 1600cc displacement, 245 cc/min injectors and a target AFR of 14, but I had to slowly step it up to 44 to get it to start and run well. I would almost expect 26 or so if I’d made a couple of improper assumptions, but the jump from 13.6 to 44 suggests I must be plugging the wrong number in somewhere.

Interesting enough, I have just discovered that the online calculator in the the MegaManual returns 44.1 for the same parameters. With some experimenting, the online calculator will return 11 if I set it for 4 squirts and 14.7 AFR (Gasoline in the pull down selection). I will need to compare this to MegaTune.

In any case, I was able to get a very decent idle and, so long as I open the throttle VERY slowly, I can rev it up and it spins nicely till about 4000 RPM, where it starts sounding very lean.

Full Weeknd of Trike Work; First Run Attempt Underway

The weather guessers were off, but to my favor, for it has been a very pretty weekend, with occasional showers widely spread. Had about a 5 minute shower about 8AM but it’s sunny now.

Friday evening, I made a replacement CLT sensor. I started it a couple weeks ago by chopping the thermistor out of a standard GM IAT sensor and soldering longer leads to it. I epoxied it inside a 10ga ring connector that had heat shrinkable sealing and protected it further with more heatshrink. The finished sensor is secured under a screw for the cooling tins by cylinder 1. It seems to work really well, giving quite believable readings.

I spent all day Saturday finishing the wiring, minus a couple of necessary interruptions (lunch, AutoZone, etc) and had the engine ready for first crank late Saturday night. In the couple of years it’s been sitting around and very rarely used, the battery on the trike appears to have, completely understandably, weakened. It will crank the engine about 4 rotations, all at about 9V. I decided to reach a stopping point and resume efforts on Sunday morning.

As of 11:45 Sunday morning, with a battery borrowed from the other trike, I have managed to get it to crank enough to putt-putt twice and backfire a few times. Amongst the little things found wrong along the way are the SAW and PIP signals to the EDIS swapped, the trigger wheel was off by one tooth and the plugs wired to what appears to be the wrong terminals. Against the advice of the MegaManual, I did indeed confuse the coil terminal numbers with the firing order. They are not necessarily related.

It’s nearly lunchtime and I’m letting the battery charge a bit between tries. It will only crank two or three times then I need to put the charger back on it. Considering how well the yellow trike cranks and how quickly the same battery runs down on this trike leads me to wonder if my starter is going bad. The yellow trike had similar symptoms and a new starter helped greatly!

Re: 70-something Stires Trike

We’re pretty much on the same thought process on that, on my bike I located the fan within a frontal air scoop that is used to direct air towards the rider from the opposite side on the fairing, and has a direction change device that keeps rain separate from the ram air. The fan sits on the floor of that plenum, and has the “mini” funnel outlet shape and adjoining 1″ ID hose leading on towards the alternator (in my case).
I used to have the ecm mounted out near the rear tire, and was in an area I had concerns about road splash etc, and the IP52 MS sealing rating in not extremely water tight. I relocated within a storage compartment under the seat, actually have the relay board, fuse panel, as well EDIS 4 module all residing in that area. Should the EDIS generate more heat that is reasonable I will relocate that up front near the coil pack (right in the air stream for cylinders).

Re: 70-something Stires Trike

R100RT wrote:a small, remote located computer fan […] feeding a 1″ ID hose that develops very slight but positive pressure into a cover fitting

I had thought of something like that, but I was primarily considering the potential need to cool the enclosed ECU. That seems an excellent way to do both, provided of course that the intake to the fan is kept completely dry. Blowing water in that wouldn’t have gone in normally would be bad. :) The fan intake situated very high under the body, blowing through an S-trap would work very well.

Re: 70-something Stires Trike

If your ecu box develops a water ingress situation (was a concern of mine when I had a location adjacent to the rear wheel before), an idea I added to my front mount alternator was a small, remote located computer fan (they run 12vdc) feeding a 1″ ID hose that develops very slight but positive pressure into a cover fiting over its front. This works really well in keeping it cool, as well no rain or spray gets into the workings, even tho its right behind the front wheel.

On System Redesign….

Happens twice or three times a night sometimes… :)

I do try to think things through far enough ahead to avoid starting work on major segments before I have a decent plan. Reality almost always intercedes, however, and system redesign is the result. I prefer to think of it as refinement.

Recent work on the trike has been engine wiring, which meant choosing a place to put the ECU, which is not actually designed to be outside the passenger compartment of a car. I have placed the ECU in a sealed box, then proceeded to drill a big hole in the lid for wires.

But, I think it will be well protected because I put a plate for mounting various electrics in a place that is centrally located under the fiberglass body, above the transaxle. The ECU is mounted to the “bottom” of the sealed box, but the box is suspended upside down on the bottom of the mounting plate (though it is not yet secured in the linked picture). This puts the hole for the wiring at the lowest point of the box and the ECU is inside the box at the highest point. Combined with sealant around the wire bundle, incidental spray should not be able to enter the box. The biggest compromise to this location is that it is immediately in front of the cooling fan intake. At highway speeds in the rain, it’s actually fairly likely that spray will be drawn to this area. No other mounting location is otherwise as desirable, so I hope that I have addressed all the problems.

You will note in that picture that I have mounted two fuse blocks. The one on the left is for engine and EFI stuff, the one on the right will be for chassis stuff, mostly lighting and instrumentation.

The row of relay sockets shown will be shortened somewhat. The forwardmost socket will interfere with the body. At this writing, only two of the sockets are in use, one for the main engine power and one for the fuel pump and O2 sensor power, as recommended in the wiring diagram in the MegaManual. The rest of the relays are mostly to allow me to use small gauge wiring to the handlebar switch pod.

I have also layed out the location for the EDIS stuff. Note the mockup of the plug wires. There is a tiny bit of concern about having the coil pack physically near the ECU, but I’m willing to try it. The alternative locations for the coilpack all involve building some kind of bracket for it and/or dodging some moving part or hot air flow.

Re: 70-something Stires Trike

I wrote: After that, it’s just wiring. A lot of wiring, but just wiring.
When is wiring just wiring? I thought I had my wiring in pretty good trim, but after a season of tuning efforts, and hind sight, I put the project back into my surgery zone (in house, basement workshop) and totally rewired and relocated key items like Micro Squirt, relay board, etc. Seemed like things kept changing as I discovered what was working and what didn’t, that ended up requiring a total rethink on the original plan :?
I look on that as normal and fun, family tends to see it as compulsive MS disorder behaviour (CMSDB if you will) :roll:
Good luck on yours.

Malaria, Anyone?

Before the swarm of Asian Tiger Mosquitos chased me in the house, I got several more important bits done, leaving plenty to do tomorrow during the day while the vampiric minions from the East are busy dying from the Yard Guard.

While I will also be dropping the body off for upholstery, I intend to try to get enough done to attempt crank the engine. Admitedly, that’s pretty ambitious, butcha gotta have goals…

Mechanically, the biggest thing will be finishing off the fuel tank, which is putting the pump in it, putting the filler on top and mounting it. I also need to cut and mount the plate that all the relays and such will be mounting to.

After that, it’s just wiring. A lot of wiring, but just wiring.

The throttle body has connectors for the TPS and IAT sensors, as well as the IAC motor and two injectors.

Speaking of injectors, I still have not been able to identify the EX650 specific injectors well enough to discover their flow rates, so I substituted two injectors from the throttle bodies I removed from Buzz. Their flow rate is known to be 245 cc/min. Guessing at a couple other values and plugging them into the Req_Fuel calculator, these injectors should provide a reasonably long idle pulsewidth. This was a big issue with Buzz, where a 538cc engine was trying to idle when supplied with fuel from four of these injectors. This 1600cc engine with only two of them should be a better match. The nose of the 245cc injectors is slightly shorter that the stock ones, but I don’t expect it to be a problem.

But back to the wiring…

I have a waterproof box to put the ECU in. Hopefully it won’t run hot in there. All the relays and fuses will be on a plate or board just in front of the engine.

Re: 70-something Stires Trike

R100RT wrote:Very nice work, and project coverage.

Thanks! Having seen your own project documentation, I consider that high praise. :) I have browsed a LOT of these stories. I try to emulate the ones I have learned the most from, thus I tend to explain as much as I can, even when I screw up. It may help someone else. Heck, I might need to refer back to it to see what the heck I was thinking when I did *that*…

Plus, I like to write almost as much as I like to talk.

R100RT wrote:Will your front wheel (I assume that’s the one you’re showing?) have disc brakes on it?

The front wheel is from a Honda Passport. I will be using the stock drum brakes. On a VW trike, especially one with a small front wheel, the front brake is little more than a handy way to keep the trike from rolling around at a red light. Between the light weight on the front and the relatively small bit of contact patch with the pavement, the front brake does not contribute significantly to the overall braking performance. It is easily overwhelmed by the relative bulk of the rest of the vehicle.

The old wheel has a really badly rusted section on the rim, so I wanted to replace the wheel for safety reasons. Since the “new” wheel has a functional brake, I have decided to use it. Besides, there is some question as to whether or not a trike with no front brake is actually legal in Texas. There are plenty of them out there, but there is conflicting information about it in the Texas Transportation Code. One bit says that rear brakes are all that is needed if they meet braking performance standards, which are fairly clearly defined. However, another bit says that brakes are required on all wheels of motorcycles, and since trikes in Texas are registered as motorcycles, many inspectors require brakes on all wheels.

R100RT wrote:…I’m considering stripping everying, and going with powder coating.

I personally like the look and feel of powder coating. I am very lucky that a friend works in a facility that powder coats some of their own products. So long as the color limitations (black, gray or baby poop brown) is not a problem and I’m willing to wait an undetermined amount of time for them to get around to it, I can generally get almost anything powder coated in exchange for beer. Since black is the only real choice with that, I decided that paint would be better for the wheel. Hopefully, I wont destroy the finish lacing the wheel.