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85 Nissan 300ZX turbo no start MS2 ver3.57 firmware 2.890

Posted: Thu Mar 11, 2010 7:00 pm
by zjasonz
I am attempting direct coil control using the stock Nissan optical sensor and I am hesitant to keep trying to start the
car. I have read a lot and followed the writeups on DIY's site and a few Nissan specific sites. I am pretty sure it is wired correctly and I have some basic setting wrong. I installed a 1K,1/2watt resistor on pin 24: 60 degreed signal from sensor.
I think its working on the stimulator as I see ignition advance increase with rpm, but i get no spark when I try to start the car. Pin 36 goes to the negative side of the coil and the postitive side has 12v ignition signal, also 12v starting.
I tried changing input capture from rising to falling. I also tried changing trigger offset to a great degree. The megamanual documentation seems to all be related to Megatune and doesn't seem to correspond intuitively to what I see in the Tuner Studio software. I know the jumpers are set correctly for the optical input. A test light on the negative side of the coil glows dimly anytime the ignition is on and during cranking, no pulsing. I think I either have some base settings
wrong relating to cranking or a bad VB921 ignition driver, hopefully not both :oops: . The car runs fine on the stock ecm which is wired in parallel but disconnected entirely when using MSII. I have two questions:

Could someone please look at my settings and give some feedback?
Is it okay to disconnect the two injector wires from MS during cranking to avoid flooding the engine?

Any help would be greatly appreciated.

-Jason

Re: 85 Nissan 300ZX turbo no start MS2 ver3.57 firmware 2.890

Posted: Fri Mar 12, 2010 6:12 am
by Matt Cramer
First question: Do you see RPM in the tuning software when you crank the engine?

Re: 85 Nissan 300ZX turbo no start MS2 ver3.57 firmware 2.890

Posted: Fri Mar 12, 2010 4:34 pm
by zjasonz
Thanks for responding. Yes, I do see 250 to 300 rpm in Tuner Studio during cranking. It fluctuates a little but seems to coincide with the engine and looks accurate. I think I might try to flash the firmware again. I burned some settings while the stim was turned on, and while the car was on, but not during cranking. I also read somewhere that the injectors should not get power when the MS is off. My injectors get 12v straight from a fuse link off the battery, this is stock wiring. I welded a bung for the IAT today and am anxious to get this thing started so any help would be greatly appreciated!

-Jason

Re: 85 Nissan 300ZX turbo no start MS2 ver3.57 firmware 2.890

Posted: Fri Mar 12, 2010 5:25 pm
by Bernard Fife
Jason,

Yes, you don't want the injectors powered while MegaSquirt is not, this can flood the engine. So you might check your spark plugs to see if they are wet. And yes, it is okay to disconnect the injector wires while cranking (though pulling the fuse is easier).

There are a bunch more 'start-up' tips here: http://www.megamanual.com/ms2/tune.htm#howto

A datalog log might help too, if you could post one of a cranking attempt.

Lance.

Re: 85 Nissan 300ZX turbo no start MS2 ver3.57 firmware 2.890

Posted: Fri Mar 12, 2010 6:21 pm
by zjasonz
The injectors aren't firing when MS is powered down, but I though I read there was a possibility of ECU or driver damage if they were wired this way? I can't seem to find where I read that, but anyway the injectors aren't leaking down, I'm just being overly cautious I guess. Thanks for the like, I'll go check it out.

Re: 85 Nissan 300ZX turbo no start MS2 ver3.57 firmware 2.890

Posted: Sat Mar 13, 2010 2:32 pm
by zjasonz
Everybody point and laugh at the noob! Apparently I have no ignition driver installed at Q16. I'm off to read some more and may try to use the stock transistor, but will probably order the BIP373. And Instead of experimenting with the stock coil, there may be some well proven settings on another vehicles coil that I could use instead. Thanks for the help, I'm sure I'll have a few more questions. Maybe next time they'll be a little less obvious :lol: