It Ain't Running Right!

[Reverend]

Sparks were blue, but apparently very small. My friend said that it should be at least 1 cm spark, but i saw only small ones, maybe few millimeters. But i do not remember were they in between the gap or outside of it. I truly, madly, deeply hope its the ignition module.

 

My no-points system is oem 240z distributor with custom made ignition box and interiors. Been driving with those since 2009. Too bad i dont have spare distributor, but i shall wise up and get one extra. Could coil work at "half-speed" or something? I measured ohms from coil and ballast resistor, ballast was about 1.7 ohms and coil was about the same. I dont know jack squat about electronics but those readings should be okay?

[bartsscooterservice]

No way your getting a 1 cm spark, maybe with msd pro mag, but not with a stock like system. The spark should be steady between the tip and the center electrode, and not interupt. Not big, but clearly visible.

Edited April 29, 2015 by bartsscooterservice

[Reverend]

Yeah, it was clearly visible. So then the problem has to be in the amount of current (too low?), or in the distributor distributing it unevenly somehow...?

[Reverend]

Its all crazy. I see spark coming from the plugs when i tested them with my old coil, and tested that the resistance was okay. I fight for weeks to get my Z running for the big car event in 1.st of may. Then, as a final resort, i went to parts shop and got a new coil, just to rule that out. And guess what....it was the goddarn coil all the time!!

 

I dont usually smoke, but i have cigarets just in case i want one. I light one just after i have finished assembling all the stuff, coil, distributor (wich was tested by the guy who built it and verified as working, i saw the testing equipment and how it produces nice blue spark) yet another set of new plugs and new coil wire. After the nerve calming cigaret, I sat in the car, pressed gas 2 times so that the carbs get enough fuel to start and left the throttle halfway open. Turned key and BRAAAAAAPPPPP. I almost $^!# myself, it was like Z was angry at me for not seeing the obvious. It idles like straight from factory line (well everything else has been tuned for DAYS so i would not excpect nothing less haha)

 

Now i have this stupid grin on my face and i can't get it off, help

[Mark Maras]

Don't know if you're familiar with the Peanuts comic strip but Snoopy had a happy dance that is appropriate for this occasion. Congratulations.

[bartsscooterservice]

Yeah, it was clearly visible. So then the problem has to be in the amount of current (too low?), or in the distributor distributing it unevenly somehow...?

 

Seems my ignition guess from last wednesday was in the right direction. Looked familiar because I saw the engine shaking, and it's a sign of bad ignition. But like I said, and like you describe above: you see a spark and think it's okay. But it won't fire onder compression in the cylinders !

 

Good thing you sorted it out before the car event ! ::

[Reverend]

Yeah, i know Snoopy ::  Still not on the clear, i have to inspect the car today, have to keep fingers crossed. For now its running with ballast resistor, whats the pro's and cons running without one?

[bartsscooterservice]

According to what I have read in the MSD manual, the ballast resistor is only needed if you use breaker points.

[Captain Obvious]

Awesome! Glad you found the issue and glad it was as simple as a new coil. Did you get it done in time for the show?

[Captain Obvious]

According to what I have read in the MSD manual, the ballast resistor is only needed if you use breaker points.

 

I believe that's an oversimplification and it's not that simple. It comes down to "dwell time" and the exponential relationship between time and current which will flow in an inductor. I'll go into the details if you want, but the simple answer would be something like:

 

It all depends on what's controlling the dwell time. If the dwell time is well controlled and is short enough, then you don't need a ballast, but if the dwell time is too long, or if it's not controlled under all conditions (like in a points driven system with the engine off), then you better have a ballast in the system or you'll likely damage something.

 

The electronic ignition systems, especially the newer ones, control the dwell time electronically and can limit the coil current adequately without having to resort to using a ballast. Older systems or mechanical systems do not.

[Reverend]

Yeah i was in the show today, lots of fun and 2 other s30's were there too BUT. Its not all dandy yet. I was so happy to get it running and driving, i seem not to notice that it stutters and sneezes occasionally. Well i've been driving maybe 100 kms in two days now and been tinkering with fuel pressure. First i tought it would be good idea to dial it down a bit (i dont have gauge btw) so i did that, if that would help leaning the carbs a bit. Well it stumbled a bit more after that so i turned it up a lot. After that it stumbled even more. After adjusting it somewhat to the point where it was, i noticed that even carbs get even flow of fuel, and all the idle screws are open 1.5 turns, it still spits from rearest carb, and especially from cylinder 6. Why from that particular cylinder? Because its in the end of fuel line, might it be, that it does not get enough fuel? Because i turned it open more than others, and it pops and sneezes over 3K rpm, when main jets are kicking in. To me, that seems like fuel issue..right? Could i compensate it by raising float instead of trying to open up the idle screw as much as i can?

Edited May 1, 2015 by Reverend

[240260280z]

Could be dirt obstruction in #6.

 

#5 & #6 share same fuel bowl so it  should be bad on both if it was fuel rail/pressure.

 

Swap the idle and main jets from barrel #6 with barrel #1 for shitz N gigglez

Edited May 1, 2015 by Blue