z-ya

I'm a Sales Engineer for LeCroy, so I've got quite the selection at my disposal. Using a $20,000 scope debugging Megasquirt problems certainly is overkill

OK, hear are some screen shots from my scope. On this one, the top trace is voltage on the injector driver output, and the bottom trace is current. The current limit is set to 30%, and the time is set to 1.3ms. These are the correct settings for most low Z injectors. You can see on the voltage trace that the driver drives the output to ground for the injector peak current period, and then pulse width modulates (PWM) the output during the hold period. Hear is a zoom of the voltage trace showing the PWM. If the time threshold is too long, the injector will never go into PWM mode. The injector driver will essentially ground the driver side of the injector, allowing it to draw max current for the entire opening time. Because there isn't a current limiting resistor, all of the power is dissipated in the injector coil, which will cause it to overheat and fail. If you are using small injectors, the opening time can be long, increasing the probability of injector damage.

Rick, Yes you can damage the injectors by setting the time threshold too high without limiting resistors. So if you had it set to 25ms, and the injector opening time is set to 12ms, the injector is allowed to draw 100% current for the entire opening time (12ms). Hear is an example of the time threshold being too high: So essentially you are allowing the injector to draw max current after the injector has already fully opened. The MS has overload protection to protect itself, but nothing to protect the injectors if the PWM settings are incorrect. It sounds like you have made all the proper checks, but still no fuel. So unfortunately, it sounds like the injectors. The voltage waveform on the - side of the injector should show 12V when the injector is closed, and zero volts when it is open. I'll try to probe one this week as an example.

To use an EDIS-6 module, you must use a 36-1 wheel. The nice thing about EDIS is that it has a limp home mode. If something in the MS timing output signal path fails, the EDIS will fix the timing at 10deg. The EDIS system is self contained, and doesn't need the MS to operate. If you want individual coils per cylinder, use the LS-1 coils (or any other with the ignitors built in). Figuring out where to put 6 VB921 drivers, and then mounting them for heat dissipation and reliability is a lot of work (and trial and error). GM already did all the work by integrating the driver in the coil. If one fails on a long trip, you can get one at any parts store.

Yes, chances are they have very close to the same opening time. I can measure it if you want to send one to me. PM me if you are interested.

Cheap wheels + track day = disaster. Get some good quality cast, steel, two piece, or three piece wheels. I use Panasport cast, and Centerline two piece on the track. Steel wheels are fine, but can be heavy. You can get a set of Centerlines cheap, and they are super strong. I paid $98 each for 16x8 direct from Centerline. I don't care about the style, I just want strength, and light weight.

You don't need to go to that extent. A clean workbench covered with fresh newspaper. Plenty of paper towels. Clean and dry compressed air. Patience, take your time!

That 4GA wire will add inductance, but no measureable DC resistance! What you need is an LC filter (inductive and capacitive). This is what most of these car stereo filters have in them. They filter most of the low frequency (audible) noise on you cars 12V source. The MS has a 0.001uF capacitor inside, which will filter most high frequency noise that the MS could care about. You can build your own filter using this equation and calculator: http://circuitcalculator.com/lcfilter.htm You only need to filter the power going to the MS (not the coil, fans, injectors, etc.). So pick a filter with a max current rating of 10A. The MS probably draws around 1A by itself.

The alternator runs off the drive shaft. This puppy won't be do'in too much idling...

Next time try Courtesy Nissan. The last set of Nissan main bearings cost me around $80. Rod bearings were around $59. Sealed power makes good products. You should be fine with them. Just make sure everything is CLEAN when you assemble your engine. Make sure there is no grit anywhere, especially in the bearing seat, or on the journals. Then use clean motor oil to lube the bearings (journal side), and journals.

The embedded code should not just corrupt itself for no reason. Usually a hardware problem causes this. For example, if there were excessive noise on the boot pin (27) of the CPU, it could cause the CPU to enter bootloader mode. This may cause firmware corruption. They have a voltage divider setup off of the 12V, so when the boot jumper is not installed, that pin sits at 1/6 of 12V = 2.0V. When the jumper is installed, it essentially grounds the boot pin, put it into bootloader mode. I'm not sure why they pull the boot pin to a potentially noisy 12V, when they could have used 5V from the regulator, which will more stable, and cleaner. There really isn't any low frequency filtering on the 12V that the boot jumper is using. There is a MOV, which might help. Bottom line: adding a filter network to the 12V source for the MS could minimize this if in fact it is the cause. A car stereo noise filter might help.

The last build I did the machining cost $1250, but this is first time I've used him, and he kind of nickel and dimed me on the cleaning. The machinist I usually use, charged me like $100 to clean everything.This new guy charged me separate for the block, rods, crank, head, and misc parts. The total for cleaning was like $300. - Hot tank block, head, oil pan, and misc parts - Magnaflux block, crank, and rods - Check and resize rods - Check and polish crank - Remove old and install new pistons on rods - Check deck flatness and resurface - Bore 0.020" over - Check and resurface head - 3 angle valve job - Check springs, guides, valves, etc. The machining work was excellent. It is runnings, and I'm measuring 200psi on all cylinder hot, so all looks good. I'll have it on the dyno next week and will post results then.

I've reused head, main and rod bolts on many builds without any problems. Chase the head bolt threads, and oil the threads before inserting them. If you want to replace them, use Nissan bolts. ARP studs and bolts are overkill unless you are building a big HP turbo motor. Use Nissan bearings and a high quality gasket set.

A good quality drivers seat and harness will make a huge difference in your times. If you still have the 280Z seat and seat belts in there, get a decent race seat and a 4 point harness. It should be tight enough so that you don't need to use any effort on the dead pedal to stay put. It is amazing how much faster you are when you don't have to waste energy and thought trying to stay in the seat. I used to be 3-4 seconds slower than a good friend of mine. After a new seat and harnesses, I'm consistently 1-2 seconds faster than him (even in the same car).

You fuel pressure at idle should be around 38psi. This could have something to do with it.

Save yourself some grief: http://www.radioshack.com/product/index.jsp?productId=2062643&cp=2032058.2032227 Encase it in plastic sleeving or tape to protect it. Use a separate cable for PIP, and SAW (don't run them inside the same shield).

I not sure about the logic behind your math, but after setting up my stimulator with your settings with 150 in the appropriate VE table bin, at 7000RPM you are at 100%. What are your VE bins set to at 6000, 6500, and 7000RPM at 100kPA? You may not be hitting 100%, but if you run 95-99% for long periods, the injectors will cause the drivers to overheat. The driver circuit has a thermal overload feature, which basically shuts down the injector drivers. By lowering the PWM setting, you are limiting the amount of current that the injector can draw (hold current). The problem is that if you set the PWM too low, the injector won't open because the peak current is being limited too much. If you have an adjustable FPR, you could increase the pressure, then retune using the required fuel. what is your fuel pressure BTW?

The important part of shielding the PIP and SAW signals is to on;y tie the shields at the EDIS module. There are shield pins on the EDIS, use those. Leave the shield unconnected at the MS (tape it up so it can't touch the chassis too). Also only connect the shield at the EDIS module for the VR sensor connections. All this will prevent ground loops, which can have a negative effect on the signal quality of the PIP, SAW, and VR signals to and from the EDIS module.

What was the max duty cycle you were hitting at the track? If you are close to 100%, the injectors and drivers will get quite hot. Limiting the current more will keep the injectors running cooler. So my guess is that you are close to 100% duty cycle at max power, and the injectors are overheating. Adding more current limiting solved this. The problem is that at lower duty cycles, the injectors may not open up all the way with the extra limiting. So around town, it may run a little lean. Best thing to do is increase the size of you injectors, and re-tune.

That IC is the RS232 translator. In simple terms, it translates the +5V logic levels to and from the CPU to RS232 levels that you PC can understand. If this device fails, the MS should still function, but MT won't work on your laptop. cygnusx1, most likely the problem is an intermittent connection somewhere in the MS. A good visual inspection of all solder joints will reveal the cause.

Get your fuel pressure issue fixed, and get it back on the dyno. $450, for how many hours? Seems kind of steep considering that you could do many runs because of the fuel pressure issue. The Walbro pump should work fine.

Get a stock one that the chrome isn't too good on, weld up the extra holes, bead blast it, and paint.

The important thing is to get a known good harness, ECU, and sensors (and engine too for that matter). So finding a ZXT that runs great, but the body is junk, is your best bet.

I never tuned a Tech II, but there must be a way to calibrate the TPS to the system. Check your manual. The middle pin of the connector should go to the ECU. One of the other pins should have 5V on it. The other should be ground. You need to determine the proper polarity. Use an Ohm meter to check this. At idle, the resistance between ground and the middle pin should be close to zero. At WOT, the resistance should be maximum (like 5KOhm or so).

It sounds to me like detonation. What is your full advance ignition timing set to? If it is an NA distributor, and the timing is set as if it were an NA, the total advance will be around 30deg. Way too much for a stock turbo motor. What boost pressure are you running? If you are running more than stock, yank the boost controller out for the time being and see if the problem goes away. I've seen people use NA electronics with a turbo motor, and we couldn't get it to run just right. We also had to back off the timing a lot to prevent detonation. This made the sluggish when not under boost.