Weak/No Spark, Running out of Ideas

[Fridge Gnome]

I have a 1983 L28ET, with Megasquirt 2 V3.0. I'm using direct coil control and have IGBTIN wired to JS10 and IGBTOUT to IGN. BIP373 is installed with mica insulator.

 

I'm having trouble getting a spark while cranking. I have always had issues with a weak spark and the car running rich when it would start up in the past. Although being able to get the car to start was intermittent. (Car is still a project and has never run well enough to put on a road.) I have used output test mode with one spark plug connected directly to the coil and get a good purple spark that way. However, with the spark plugs out of the engine I am not seeing any spark while cranking until I let off the key and then sometimes a spark or two will appear as the engine is still spinning after the starter is turned off.

 

I am getting about 11v at the coil while cranking. This is the only difference I can see between output test mode and cranking. With output test mode I have about 12.4v at the coil. Is 11v too weak to produce a spark?

 

I have a new coil, distributor rotor and cap, spark plug wires, condenser, and alternator (internally regulated).

 

I do get an RPM signal in tunerstudio when cranking. Although I have the crank rpm set to 200 and the tach in tunerstudio is reading around 350 rpm. Is this abnormal?

 

I'm running out of ideas as to what the issue could be. My next option is to just start throwing new parts at it and I'd rather not do that blindly.

 

Any help would be appreciated.

 

 

 

 

 

 

 

 

 

[Chickenman]

What precisely is your Coil make and model? What  plug wires are you running?  What plugs and plug Gap are you running. 

 

Next post up your CurrentTune.msq and I'll have a look at it.  You probably do not have the dwell times matched to the coil.

 

Certain coils, like an MSD Blaster 2 require a LOT of dwell. The MSD Blaster 2 is a poor choice for an inductive ignition. They are designed for a CDI ignition and just don't have the correct properties to work well with an inductive ignition. The stock Nissan 280Z coil will put out more sparkenrgy than an MSD Blaster 2 coil,, unless you really crank up the dwell to the MSD coil. It is a very  slow saturation coil when used on Inductive ignitions. 

[Chickenman]

PS: What new condenser are you referring to? There is no condenser used on the 280Z distributor. At least not like on a points system. 

Edited June 3, 2018 by Chickenman

[Chickenman]

A very good Coil that matches with the BIP373 drivers is the AllStar 81230 E-Core coil. AllStar is a large supplier to Circle Track racers. Very reasonable price and this coil will pack a wallop!! Set nominal dwell to 4.0ms . Available at Summit, Jegs, Amazon. Justs about anyplace. 

 

Make sure your Primary wiring to the coil positive and negative are large enough. 14 gauge minimum 

[Chickenman]

Grounding is also very important . Particularly with a Nissan Optical distributor. The MS ECU main ground should be grounded on the Intake manifold.  As per MS Extra instructions. The factory ground point on the Intake manifold is ideal. Do NOT ground the ECU to the Chassis or worse to the Battery negative terminal. The starter can pull over 150 amps when cranking and this can induce enough voltage in the ECU ground wire to feedback and disrupt or even damage the Microprocessor. 

 

 The ground wire on the 4 prong plug should go back to the ECU sensor grounds. Then add an additional ground wire from the distributor body directly to the Intake manifold. And make sure that there is a good ground connected from the engine to the Chassis grounding stud on the Firewall. 

[Fridge Gnome]

Thanks for the reply.

 

Coil is an Accel SuperStock 8140C, I've check primary and secondary resistance on it and they appeared to match specs.

 

Spark wires are Taylor 8mm.

 

Spark plugs are ngk iridium and the gap is around 0.041".

 

I've played with the dwell some, but I did not notice any impact while cranking.

 

I might be confused with the condenser, I had read in a few places that it could cause a weak spark. The car itself is a '77 (77 body, 83 engine swap), so had a condenser attached, I didn't know the 83s had no condenser. I attached it to the "negative" of the coil.

 

I will try switching to larger wire on the coil primary wiring. I had used the wire from the megasquirt diy wiring harness, which I believe is 16 or 18 awg.

 

As far as grounding, I remade the large grounding wire that runs along the passenger side of the engine bay with 10 awg wire. The original one appeared slightly corroded. I remade it with all the same connection points, including the one on the firewall. The MS is grounded to the engine block at the same point as that large grounding wire. I removed all the vacuum lines from the car and deleted all the original mounting points on the intake manifold, so I don't have that point available.

I will double check my grounding for the optical sensor today as well.

 

I've attached my current .msq.

 

 

2018-06-03_09.53.06.msq

[NewZed]

14 hours ago, Chickenman said:

The MSD Blaster 2 is a poor choice for an inductive ignition. They are designed for a CDI ignition and just don't have the correct properties to work well with an inductive ignition. The stock Nissan 280Z coil will put out more sparkenrgy than an MSD Blaster 2 coil,, unless you really crank up the dwell to the MSD coil. It is a very  slow saturation coil when used on Inductive ignitions. 

 

You must be confusing the Blaster 2 with some other coil.  MSD advertises it for use even with points.  Can't get much more inductive than that.  It's just a plain old coil with red paint, and a bit lower primary circuit resistance.  Probably requires less dwell than the Nissan coil.

 

https://www.msdperformance.com/products/coils/performance_street/parts/8202

[Chickenman]

1: Remove the condenser. Not needed with Ms and could be causing an issue.

 

2: Plug gap .041" is way to large on a Turbo engine. I suspect you bought NGK plugs with a -11 as a suffix. Such as BPR7ES-11 Those are wide gaps.

 

Get the Iridium or regular Copper core NGK plugs with no suffix. Such as BPR6ES or BPR7ES ( 7 is a colder heat range ) . The NGK plugs with no suffix come pregapped to .031". Gap them down to .028" if your Boost is higher than about 8 psi. The Wide gap plugs cannot be gapped down to .028" without putting a weird angle on the side electrode that will wear excessively fast.

 

3: I'll look at your .msq later this morning. Have a Remote Tuning session scheduled. 

[Chickenman]

7 minutes ago, NewZed said:

 

You must be confusing the Blaster 2 with some other coil.  MSD advertises it for use even with points.  Can't get much more inductive than that.  It's just a plain old coil with red paint, and a bit lower primary circuit resistance.  Probably requires less dwell than the Nissan coil.

 

https://www.msdperformance.com/products/coils/performance_street/parts/8202

I don't give a F**k what MSD advertises. The engineering papers on this coil and field experience from knowledgeable  racers who have run this coil on Inductive say otherwise.  And I ran it on my 1976 280 Z . Have you ever run one one. have you ever run a MS ECU or tuned one?

 

Stick to things you know about ZH. You are clueless on this subject.  BTW... for newbies to this Forum. ZH likes to Troll my posts. Don't feed the Troll.  

[NewZed]

I just like to correct errors when I see them.  It's not you, it's your errors.

[Fridge Gnome]

Ignition! Chickenman went though my tune and for some reason I had it in my head that the cranking rpm was the rpm I wanted to crank at, instead of what the megasquirt should expect. I had it set as low as possible, so megasquirt thought the engine was running instead of cranking. I also had a low cranking dwell and too high spark duration. I also swapped out the spark plugs with 0.032" gap ones. It runs rough but hopefully I finally have a stable starting point for tuning now. Thanks for all the help.

[Chickenman]

You're welcome Derek. We cam work on the rest of the Tune a bit later.