superlen

I laugh.....Sadly, because many times that's true. The connector you see is scavenged from an old ECU. The part numbers are still valid & get listed as a current orderable part, but only in extremely large quantities. To begin with I plan on just scavenging from the core ECU that's sent in. While I would prefer a newly manufactured connector, the existing connectors are robust & with a quick deox cleaning should perform just like they left the factory. Sarah, Yes, at some point there will be an Android and Iphone app. I won't write any of it until the base system is up and going though. Lenny

Here's a quick picture of the HellFire ECU. It passed it's first test. It fits in the stock ECU frame perfectly. All mounting hole locations were spot on and the stock connector attaches as it should with no interference. I do have one resistor that is a little close to the frame, but it's acceptable. It's also an optional part for someone running more than six injectors, so stock configurations it won't even be loaded. For inquiring minds, here's some technical details: 1. It's a four layer board with internal power and ground planes, not a cheap simple 2-layer. The internal planes are further split into multiple analog and digital planes to keep *ALL* the analog signals above/below their respective planes. This should give me us extremely clean analog signals from the external sensors. I'm extremely anal about routing mixed analog/digital and for many pcb designs I do it's pretty critical. For the signals on this board it's a fair amount of overkill, but it's nice to know that the signals that hits the a/d converters are going to be as clean as possible. 2. All the optional cam/crank trigger inputs are in the top right section of the pcb. They are isolated of course with their own filtered supply, and I even added guard rings to the ttl signals as they made there way to the CPU input capture pins. 3. Injector driver circuits and optional ignition drivers are all along the bottom edge. Again, all are highly isolated. The same drivers will run the external fuel pump relay & some additional general purpose inputs/outputs that someone may need. (thinking in the future for turbo/nos/shift light, ect. ect) 4. USB communication, & optional blue tooth module & accelerometer module are near the top middle. The USB connection will pigtail out with a simple cable to cabin & a female B connector. You can let it hide up over the odometer reset cable/hood latch cable or extend it to somewhere else like the glove compartment or console. Now, all I need is more time... This shows the HellFire on the bottom with my test harness connected and the stock ECU above it. For comparison here's the entire stock ECU guts. There are actually two circuit boards in the stock design with a ribbon cable connecting them.

Just another quick update. I've been sidetracked with other projects, but I did get the raw circuit boards in this week & will try and get time to populate them next week. Pics as well to follow. Lenny

Zed, Thanks for the pic. I bought a chiwanese adjustable online but haven't plumbed it in yet. I wondered what the quality might be. Hopefully, it will work out. Wiring a "prime" circuit in would also help out the leak down. Len

Steve, The Mustang sounds like a good option. Do you know if the IAR is a PWM input? Len

Captain, FYI, the Q45 & 240sx was what I was planning on playing with while testing the ZFuel controller. For TPS, Potentiometer input or switches would both work, IAC is a pwm output so any two wire IAC will work. Bosch makes a few external IAC valves that would plum in similar to the AAR (in the same location, same wiring harness plug), but I get what you're saying in that a TB with built-in TPS & IAC would be the sweetest install. Another possibility....I replaced the TPS on my Dodge Dakota the other day & looked at both it and the IAC. The IAC looks possible,with some machining of course, to meld into the bottom of the stock TB (replacing the BCDD was my thought). I do think it was be easier to use a new TB, but if one wanted to keep the most bone stock look possible this may be a route to pursue. Len

Thanks Captain, I remembered something different about 1978 (other than my Stretch Armstrong was eaten by the dog), but didn't recall what it was. I also wondered if the stock unit just used the wire running to it to sense if the pump *should* be running & then did something with that info such as... pump isn't running -> stop firing injectors. I'll know more about this in a few weeks & I'll report back. Regardless Shane, you can skip the ECU if trying to diagnose the fuel pressure issues. Len

Shane, Looks like you had a busy weekend & were covering all the bases pretty thoroughly. Are there any numbers on the aftermarket fuel pump? If so, you could look up the flow rate and we could determine if it was undersized. Obviously the stock one you have on order will take care of it if that was the problem. As for fuel pump control, the ECU for your car doesn't control the fuel pump at all. The fuel pump relay can be energized be either a) the key turned to the 'start' position or the vane in the AFM being sucked in by the engine running(or your finger if you want to test that). Note: Even though the ECU doesn't control it, there is a wire that runs from the fuel pump relay to the ECU. My assumption is that Bosch Engineers were planning on taking control of the fuel pump via the ecu from the beginning, but didn't get around to it until 78. I'm with Steve, I don't remember if the 78 took over or it was 79. I *think* it was 78. I have the FSMs at my office and can look it up to confirm if needed. Lenny

Car looks great. You'll need a new parking sign...unless you want to make your Z 4x4. I'm not sure about a screen in the tank, but there is a small screen on the inlet to the fuel pump that most likely will be gunkified. Pull the fuel pump and look in the inlet and you should see it. Lenny

Yes. You're right, the 36psi is always referenced to the inside pressure of the intake manifold.

This looks like a great test candidate for MAF. It even has the Bosch style connector, so if one wanted to go ahead and replace their AFM with a MAF, the harness would still look "stockish". New Maxima J30 I30 Q45 Mass Air Flow Sensor MAF Meter 2268031U00 2268031U05 | eBay

Hodg, I thought about the cross section changing, but I think that only affects the area right near the flap. So, the air right there speeds up, but a few inches later is slows back down to an average airflow for the round duct size. Still looks iffy doesn't it? Regardless, I'm not going to try and model it in software. I'm perfectly fine just calibrating the output and going forward. Captain, Yes, it's purposely non-linear to give more resolution down in the idle/off-idle area. I too think that putting in series with a MAF is a great idea. I had been thinking I would tune with Speed Density first and then use it to calibrate the AFM, but the MAF would be less work & dyno time. MAF was going to be the last sensor I worried with, but maybe I should make it first. Much easier than building a flow bench which I thought about as well. Time to walk the local yard & surf Ebay. FYI. I have written the firmware to actually calculates air mass flow for any/all meters that are enabled. For instance, I could get the grams/sec flowing from all the following algorithms every cycle. 1. AFM 2. Speed Density 3. MAF 4. Alpha-N The theory being that if the AFM started giving strange readings, I could revert to Speed-Denisty on the fly, like a limp mode. Most all OEM ecu's do this. If MAF goes south, they revert to Speed -Density or even Alpha-N. With the frankenMaf spliced in between the filter and AFM & an replacement linear TPS I could drive around with the test car with FOUR redundant air mass sensors. hahaha. Lenny

Shane, All the others had great info, but start with your pressure first. You must have 36psi on the fuel rail at ALL times. Idle, part throttle, WOT, under load, loafing, ect. If you don't have 36psi on the rail then you'll never get it to run right. As others posted, you're going to have to check your fuel system starting at the tank and moving forward. It's a smelly grungy annoying weekend. Lenny

Captain, Yes, you and I are thinking alike. I do equate the AFM as a velocity measuring device. Great picture,BTW I'll have to investigate those links. Hodgimus-maximus, Yes, temp does play a major roll in the mass of the air, but from my research it doesn't change the drag force on the vane tremendously. Since the air is a compressible fluid, the speed of the fluid is the primary initiator of the drag and overshadows the mass. I couldn't wrap my head around this very well until after some research I realized the "compressibility" of the fluid is what makes it this way. Then as Captain pointed out the speed gets turned to volume by using the cross sectional area of the AFM. The cross section won't change of course, so I really don't have to worry about that math or calculating any of that. I will simply use the voltage output as an indicator of volume flow. Now that we have an accurate measure of volume/time we definitely must use the air temperature as you noted to calculate the mass/time. Len

mylz, There's a big difference between the fuel pump coming on & priming the line vs the fuel pump actually pumping enough fuel to sustain 36psi on the fuel rail while your engine is running under some load. Just hearing the pump come on and load up doesn't mean your fuel delivery "system" if functioning well. It does mean the pump is pumping and that is of course step one. I don't want to harp on it too much, but Zcars are notorious for gunking up the fuel pump inlet screen, fuel dampner, & the stock under the hood fuel filter if they sit for any length of time. Even a little as a year can do it depending on the location, humidity, amount of gas in tank, quality of gas, ect. ect. It does sound like you have some major wiring gremlins to chase down, and you are on the right path to get this checked out and working. Just be ready to re-visit your fuel delivery system after you get the electrical up and going if the car doesn't just run smooth and solid right out of the gate. When your electrical buddy comes over, go straight to the fusible links & test them first. The ecm is powered through these as well as separate portions of the fuse block. Z's fusible links aren't the most robust design ever created & to make matters worse, Datsun stuck a leaky skylight right above them in the hood. Good luck and keep us posted. Lenny

Blue, Thanks for the link, I'll check it out. Also, after more research and learning about specific heat ratios and formulas involving the speed of sound, I have it figured out. The final result of all of this is that for our purposes, the AFM could only vary by about 0.2% across a temp range of 0-200C! That's a pretty small number and for my purposes, I can assume the AFM to be a perfect volume measurement device INsensitive to air temperature. The AFM's output will be *slightly* larger with colder air, but tiny tiny. The reason I kept thinking it should be affected more is because air is a compressible fluid so the density does not play a large factor in the pressure applied to the vane. For a compressible fluid, it's all about the speed. If we were trying to measure an INcompressible fluid, then the density change that occurs with temperature would be much more pronounced. Len

Captain, Thanks for the link to the numbers post. I'll have to investigate. The reason for the lookup table was that I have a common structure/component that I use for all the sensor inputs, and the lookup table is way easier to implement across different types of sensors, temp MAF,AFM, TPS, ect. Some are simple such as TPS, it's just two points as it's a linear pot, others such as temp sensor will need more. Yes, you said it right. And my lookup tables are configurable for both the number of points and the locations along the x axis, so you can spread them out where the curve is nice & linear and squeeze them together where its curving. I can just keep adding points until the error % is down to what is acceptable for any sensor. Using Steinhart-Hart in the gui is a distinct possibility to help generate the tables, but my guess is that if I have tables already figured out for the stock sensors, plus a few other common temp sensors used such as GM and Ford, those tables would work for most people. Oh also, I need actual degrees when I'm doing speed-density calculations. If I implemented only the stock LJet version, you're right I could just adjust the numbers of how much extra fuel to dump for colder air and I wouldn't need to know or care what the actual temp was. Here's some more related info, and I'd like your feedback on it. Note: for the following discussion we aren't considering any type of enrichments such as acceleration, or different target Air-Fuel ratios, ect. We just care about matching 1 part fuel to 14.7parts air. The way I have the code architecture set up is that the primary fuel calculation function takes MASS of air flowing into the engine as one of the variables. I will use this function regardless of what type of air input method is on someones car. The following are three common methods to tell the ECM how much air is flowing into the engine. M1. Hot wire Mass Air Flow (MAF) M2. Speed-Density using Manifold Pressure, rpm, & VE table. M3. Stock Bosh Vane type AFM Of the three, M1 (MAF) is the easiest for the software as this sensor typically give you an output that is proportional to the MASS of air flowing into the engine. This is perfect as the temperature of the air you don't care about because the sensor is compensating for that. This method I already have written and tested in the firmware. Now lets look at M2 (MAP) This method uses manifold pressure and a table called the Volumetric efficiency table (VE) to determine at any given RPM/MAP combo how much air is flowing into the engine in VOLUME (not mass). This is where we need the real temperature (in Kelvin no less) and use Boyles Ideal gas law pv=nRT to convert volume of air to mass of air at this temperature and pressure. Zedyone_kenobi are you following along? I may end up just buying triples as well. JK, I have this one already figured out and the code written/tested as well. Now on to M3 (our stock AFM). This one is of course the most interest to us. It is also the one that I don't understand the physics of exactly. The vane meter output measures airflow, but is that output related mostly to volume of air or mass of air? Consider two possibilities: a) volume of air flowing past without ANY regard to the density of the air volume of air flowing past but vane position changes depending on the density of the air cold/hot. The ECU definitely samples the air temp (IAT) & corrects for cold heavy dense air vs light warm air, and I'll do the same. What I'm not 100% clear on is this. Does the AFM output *also* get affected by cold vs warm air? I think it does. Maybe not by a tremendous amount but I think cold dense air flowing at a given cfm will move the vane farther that warm light air flowing at the same cfm. Regardless of how much (if any) the air temperature affects the vane position, my lookup tables will adjust it out. However, I would like to understand the physics behind it. Lenny

Sarah, That's exactly the plan..just a touch rich as shipped. Also don't forget power falls off much faster when you are too lean rather than rich. Captain, I looked at implementing the equations directly in the firmware, but went with a lookup table with linear interpolation between the points. Of course the table has to be calculated ahead of time and stored. That's where we can either measure & log real world data and/or use the equation within the GUI to make building the table easier/better. The first pass, I have just implemented the numbers out of the FSM & plan on checking/tweaking the results when hardware gets here & I can get real numbers. Len

New Update: Just finished routing the circuit board a few minutes ago. I'll turn it loose to the board house next week so I should have raw boards a week or so after that. I'll take some pics when they come in. Woot Woot! Not much new to report on software. I did add some nice sensor calibration windows to the Gui. No one but me will probably need to use it as the ECM will already be calibrated for the stock sensors. However, if someone wants to add different sensors for custom applications, this will be the cat's meow. For instance, if you make your own custom nifty intake manifold with a throttle body from a K24 engine or some other donor car, you can easily calibrate to the new Intake Air Temp sensor & wouldn't have to use the stock Bosh unit from your Z. The same goes for water temp sensors, throttle position sensors, ect. ect. Anything you want to throw at it, you can tune/calibrate. Also, I will tweak this calibration screen for the Air Flow Meter. This will make it easy to bring your AFM back into spec without adjusting the internal spring. Basically you will be able to tweak the "SPRING" electronically. I think most everyone might want to play with this to get peak performance out of there engine. (or just because it's fun) I imagine that if we took 10 cars and tested their AFMs we would get 10 different curves of voltage vs airflow. All would be close, but not SPOT on like they were calibrated at the factory. I plan to sample as many of these AFMs as possible and adjust the factory shipped calibration numbers to the middle of the road. As always, any thoughts/comments are welcomed. Superlen

Congrats on the new ride. It sure does look straight and clean! I have nothing to add for now that will be more enlightening that what the others said about troubleshooting it. Start with there suggestions and keep reporting back & it will come to life. ....Err, well I will add one more comment. Once you track down your electrical and get *any* fuel squirting, just save yourself some time and stop. Pull the fuel pump. There is an intake screen in it that will most likely be clogged from old nasty gas from sitting around. It may actually be clean enough to pass fuel to start car, but unless your engine gets a clean steady supply of fuel, it's tough to get them running nice. You may be lucky, but most Z's that sit for any length of time need the tank drained/cleaned & this fuel pump screen cleaned. While it's apart install a cheap clear inline filter from the tank to the fuel pump. This will keep the crap that is still in your tank from being ingested again and spoiling your work. NOTE: This filter goes *before* the fuel pump, not after. These clear filters are only for low pressure applications. You have a high pressure stock filter up in the engine compartment by the fuel rail entry. It probably could stand being changed too, but I wouldn't do that until you have the tank/pump all checked out. Otherwise, you will just fill your new HighPressure fine particle filter with *crap*. Check the archives for good info on how-tos. Superlen

Just a quick update. Still working on finishing up schematics & layout. - The USB cable is going to work well. - Added accelerometer on board for future development. - Have my inside Tyco source working on finding some of the stock connectors. (crossing fingers) Lenny Lenny

Carl, "Jim Cook" That's it, thanks! I was at least close. I do remember this body kit was on the cover on at least one of their catalogs. It was a white z and had some striping with lime green in it. I always loved the rear fenders, but hated the fronts. Lenny

If all the other cylinders are running great, you can skip all the sensors. Maf, coolant, fuel pressure regulator & the ECU would all affect all your cylinders. If it's just #1, I would do these in order: I'm sure most you already have. 1. Swap plug and plug wire with #2...see if it follows those, if not, your wire and plug are fine for #1. 2. Swap the injector connector with 1 and 2. Same reason. 3. Swap the actual injector (this is more of a pain, so while they are all out inspect, clean, test, ect) Lenny

My son chose 16" rims for his 77. As you are finding out, most all of them have offset that won't work with our zs. The rims he chose were no different, & I ended up using spacers. Lenny

While that may be a scarab car originally, the front/rear fender flares are not. They were sold as aftermarket in the mid to late 80s by??? I think it was Jim Wolf Racing?? or something similar. I remember seeing them in their catalog and thinking they looked way cool. I'm guessing that this is just a z with a body kit. The last photo you have throws me a little though. Maybe someone took a Scarab, added these fenders and the photo was taken for some article. I'm not a Scaraficinado in any respect so I'll gladly recant the above if someone more knowledgeable than I chimes in with better info. Another body kit that came around in the 90s was advertised in ZCar magazine was "subtle Z". It had great lines too, but I don't think they are around anymore either. Lenny