30 April

Replaced a short -10 AN hose that runs from the remote oil filter to the engine block; it’s plenty tight but has been weeping for months so it was time to fix it for good. Because it’s downstream of the filter it was critical to clean the replacement assembly well, so carb cleaner was first sprayed through it then a paper towel segment soaked in more cleaner was pushed through. I expected some rubber dust and there was that – but I wasn’t expecting this. When this popped out I though, “You gotta be kidding me” – I can only imagine the antics it had in store for my engine had it made it inside. The segment is partially anodized and that stuff can be hard as hell. Either it was left over from manufacturing or broke off when I screwed the assembly together. I’m not sure which would have done in my engine faster, this or the 1/8″ segment of stainless steel braid that also washed out…

In other news, it’s always been a mystery why my boost control valve is so sensitive. While it seems that everyone else on earth runs maybe 10-50% in order to set similar boost levels, I can only run mine up to maybe 20% and that’s roughly 20 psi boost. I’ve tried different boost control valves, I’ve tried changing the plumbing, and of course the ECU’s been changed, nothing helped. Then today, comments by someone suddenly made the lightbulb in my head go on. I think this header has such good flow to the wastegates that they only have to open a tiny bit to dump all the boost. My mistake was comparing my figures to engines with poorly-designed headers. Wastegates on many cars are mounted in all sorts of wrong positions, often at right angles to the main exhaust flow. What most people don’t realize is that if you shoot exhaust gas at right angles across an open tube, it actually sucks air out of the tube. As a result, people have to use crazy huge wastegates to make up for the poor design and run high duty cycles to get enough wastegate flow. I’m almost positive that this is what’s going on so some restrictors will be made up as a test.

With the above mystery probably solved, we of course need a replacement, which of course showed up today, a new mystery noise. I wouldn’t even mention it had it happened only once, but it happened twice. The first time I thought I ran over a rock, or maybe a tool left in the engine compartment dropped out and bounced. However, there wasn’t anything in the rearview mirror so I dismissed it as whatever it was having shot off to the side before I could see it. Then about 5 minutes later it happened again. If you’ve ever had a coil-over spring pop back into its seat with a bang, that’s about what it sounded like, but the car hasn’t been on a jack in months. Both times it happened during ordinary driving: straight and level road, maybe 45 mph, no brakes, no turns, no hard acceleration. After that I took the car out on the freeway for a few miles then back home and of course it didn’t do it again.

29 April

Sorry for the late update.

The idle mystery is solved… but it wasn’t obvious. While trying to get a handle on the poor idle control I noticed that battery voltage would start out fine but would sag. At start it would always be 14.5V, but a few minutes later it was down into the 12s. At the time I was concentrating on the idle and added it to the list of stuff to deal with later. However, idling the car for very long caused the battery voltage to get so low that it couldn’t crank, and a few people pointed out that the low voltage might be a component in the lousy idle, so attention turned to that.

Putting a multimeter on the alternator confirmed that the problem was real and not just the dash (that’s another story…). The possibilities were a heat-related failure of the alternator or a slipping belt, but neither seemed likely when idling for just a few minutes. Turns out there was a third choice. When I wiggled the wires plugged into the alternator, the voltage went up; bend the wires the other way and it dropped off again, so the problem was inside. Taking it apart and… well, I’ll have to yell at the guy who soldered the wires together.

With that fixed, suddenly everything behaved better – everything responded to reason! I suspect that the connection was being made and broken at about the same rate that the idle control was trying to correct it, and like pushing a kid on a swing, it would get worse and worse before causing the engine to quit. Cold start and idle are now vastly improved. Sometimes it still has an issue when approaching a stop though, especially if I don’t push in the clutch early. It’ll sort of bobble around at 800 rpm, then slowly recover back to 1000. It never stalls and it isn’t a big enough issue to stop working on other things.

Next was setting up open-loop boost control, using the same 3-way MAC valve that everyone else uses (and every company labels as their own). Somewhat surprisingly, I’m seeing the exact same high sensitivity to duty cycle as with the KPro. Examples seen elsewhere (including in the manual) show this same valve changing boost by 2 psi with a 10% change in duty cycle (five times less sensitive). I can’t figure out why my setup acts so different. I’m running a twin-scroll turbo so there’s two wastegates, but if anything I’d expect the increased air volume to make boost control less sensitive, not more. Maybe I have a “defective” boost control valve that works too well? Doubtful…

If the wiring to the boost solenoid was intermittent, it would have less control, that’s not happening. If there was a leak somewhere in the hoses or wastegates, it would have less control, not more. FWIW, early on (with KPro) someone convinced me that the entire problem was due to using the wrong valve, that I needed to use a certain 4-way MAC valve instead. It was even worse. Lastly, someone said I may have to add a small orifice (a restriction) in the hose leading to the wastegates, to in effect, desensitize the boost control valve. That should work, I’m just puzzled why it needs to be done at all. (I have a hard time believing that my boost control plumbing flows soooo much better than everyone else’s that I have to dumb it down.)

I haven’t engaged closed-loop boost control yet but wonder how well it controls the loop with such a sensitive valve.

19 April

All my spare car parts sold and everyone’s a winner; I get shelf space back and some money and buyers got some great deals.

The week was spent trying to stabilize the idle – much (or perhaps all) of the flailing about being due to my inexperience. The problem is an unstable idle: surging, oscillating, and a frequent stumble. The inability of me to get a solid idle isn’t what worries me, it’s the source of the stumble – the initiating factor. It was suggested that it might be due to the larger (1650 cc) injectors being unable to do small duty cycles, and that the fuel is puddling, but I don’t buy either. Since E85 needs 30% more fuel, that’s the same as running 1000 cc injectors on gas – which is what used to be in there and ran without issue. Also, the puddling can only happen if there are low areas downstream of the injectors for it to collect in – there aren’t, it’s all downhill straight into the cylinders.

Note that the issue involves idle only, above that and Midlana is a rocket. I haven’t even gotten on it hard due to space constraints and the idle drama at every stop light causing the engine to frequently stall. With a small battery, I can’t afford too many stalls because the battery doesn’t get much of a recharge before it happens again. So, for now, I’m slowly circling the opponent, looking for a weakness in its idle puzzle.

12 April

Well, it’s working, but it wasn’t fun getting to this point for something that could have been so much easier.

It was a tough week figuring out how to get the MXS dash unit to display the correct units, until my spirit was crushed. The problem was solved, just not in the way I wanted. I wanted all dash data to go through one interface – the CAN bus – and it does, except that the dash forces the wrong units on it. The dash designers figured that they’d take care of displaying units for the customers. If you send over a variable on the CAN bus by using spare analog inputs on the ECU, the dash programmers decided that, “well, since it’s an analog value, it’s in volts, so it makes sense to display it in “mv” (millivolts) – you just can’t change it.

No, no, no. The number of customers who want to display “mv” on their dash probably numbers about two; everyone else wants to display, oh, you know, useful units like psi, kpa, degrees F, degrees C, gallons, liters, etc., etc., but all we get is “mv.” What the heck was their marketing department thinking? They need to hire me…

So as the picture shows, it’s working, but in order to get here meant giving up on the CAN bus, taking raw sensor voltages and running wires (around the ECU) directly into the analog inputs on the dash – an inconvenient, unnecessary and redundant step. The ECU has the values, the ECU sends the values, the dash receives the values – they just lock scaling and units with no way to change it. Once they break your will and you feed the dash with analog values, it’s great at scaling and labeling the inputs. They just completely dropped the ball since all the variables were already there in the CAN packet…

So when dash vendors tout a CAN bus interface as “the” solution, don’t believe it. At best, you’ll get a few engine variables, engine rpm and maybe coolant temperature, but not much else. For other apparently unimportant things like oil pressure and temperature, you have to do it the old fashioned way if you want meaningful units. (Looking at the picture, I see I forgot to change “MAP” to GPS speed.)

7 April

Well son of a… it “just works”, note that the bar graph and numerical RPM on the AIM MXS dash is displaying engine speed. Next is getting the oil pressure, oil temperature, and coolant temp scaled correctly. The “mv” (millivolts) units shown is a goof on AIM’s part; while technically correct (they are analog inputs) virtually no one uses “mv” units; they use psi, degrees, amps, etc. However, I have to cut them some slack since the unit is brand new to market; when I bought mine they said “you’re the first to buy one!” For a new product, that’s not always a good thing to hear(!) but it’s how the timing worked out. I’m very happy that the CAN interface works because it’s critical for my overall system. The gray bar across the top consists of 10 LED shift lights; I purposely chose a display layout with a small tachometer bar graph. The LEDs are more important when it’s time to shift, and the small barograph frees up room for other variables. There’ll eventually be two screen layouts, one for the street and one for the track, with the track layout having more timing information. The lighting in the photo isn’t great because the garage door was open and it was sunset, causing a bit of glare.

5 April

Went on a short business trip out to southern Arizona and was very impressed with the area; the high desert is surprisingly green this time of year. Turns out that the area actually gets more rain than we do here and while it gets a bit colder in the winter, it doesn’t get as hot as here in the summer – I didn’t expect that at all. Other surprises included gas being a full 30% cheaper, and there were a TON more cops on the road. Without exaggeration I saw more cops there in one day than I do here in a month. Also talked to a gun enthusiast there who matter-of-factly said that fully-automatic weapons were perfectly legal, as are suppressors (silencers) – a totally different world.

The situation at my day job has changed a bit; we’re now taking turns at one-week on-call sessions, so it’s random chance how our “spare time” goes. So far I’ve gotten a bit beat up over the last three days and it made progress on the car impossible. The good news is that the AIM MXS dash arrived, though I haven’t yet connected the all-important CAN bus to the ECU to see if it “just works.” Assuming that the interface works, there’ll still a week or two of configuring and scaling various sensor channels.

My brother says there’s another track day at Autoclub Speedway in Fontana in about a month, so the timing is right. I’d really like to get a “rematch” with Willow Springs though. As you may recall, my weekend was cut short due to some bonehead installing the fuel filter backwards and it cutting off fuel flow. Would be nice to get back out there and see how Midlana does – before it gets too hot.