Ignition testing

[familyMAN]

Only input I can add is when I was shopping and comparing BAS vs DLI, Matt M suggested DLI because boost-a-spark would blow ECI fuses at the most inconvenient times. Like impromptu race. So I told him to write up my order for DLI. Didn't have any, couldn't get any and sent me to another vendor that had them in stock. That told me all I needed to know. Bought a DLI.

I've been running my DLI on both 6g72 and 4g63. Not hot-wired Stock coils for the respective engine. 6g PTU on both. Donniekak gets more out of his stock 4g coils without an ignition amp than I do. Could be PTU difference since he runs 4g PTU or it could be worse wiring in 3S to coils.

DLI has done the trick at up to 38psi, .022" gap, (600+ awhile thru auto) and even lights off at low 10s afr on E85.

I'm not even a mechanical engineer so have no idea how or why DLI works but it does, for me. I'll let you guys know how 40+ psi works in the spring.

[bradrs]

I honestly can't answer that one without testing. What I can say is that the stock coils look to be more than adequate for a strong Inductive Discharge system

The 3S coils look to be the same as the DSM coils I tested. They are very good coils, the only downside is charge time. Bumping up the charging voltage cuts the charge time to hit a certain amperage.

Aside from that, they have a decent inductance. And it has a reasonable turns ratio, so it will provide decent output voltage. And more importantly, their charging time is matched to what is in the dwell table for the ECU. Changing to a very different coil means you need to remap that.

Hi Adam. I think the benefit of BAS over hot wiring the coils will be that the voltage should stay constant at the coils with a BAS whereas it is likely to droop with the hot wire setup due to demands on the charging system. IF I was to make my own BAS I would build something that regulated the output to ~15-16 volts for the coils and was independent of charging system loads. The stuff that Jester found could do the job far cheaper than a KB BAS.

But most ECUs will compensate the dwell time to adjust for battery voltage change. If you are feeding just 15-16V to the coil and not the ECU, it would do that voltage compensation based on the cars voltage which is fluctuating, as you say. So the hotwired coil would be more consistent, as the ECU would be correctly compensating for the voltage. You'd definitely need to play with the dwell settings to account for that with a BAS setup.

On the other hand it is a proven fact that Capacitive Discharge ignition (CDI) provides a much hotter spark than Inductive can. In theory the DLI would let you run the largest possible spark plug gaps and light off the mixture with more control. The reason is the CDI is able to hold the high voltage for a set pulse duration whereas the BAS just cranks up the primary side so that the high voltage side hits a higher level but without a controlled duration. That said CDI might not be better than BAS in practice.

CDI has a downside of much shorter duration than an inductive spark. Multisparking is an attempt to make up for that. But really, a long inductive spark is going to be better for lean mixtures at idle/cruise.

CDI will often hit a higher voltage on the coil primary(500V vs 300-400V with inductive). And because of the short spark, it is usually a much more intense spark. To visualize this for the non EE types, think of your spark energy as a big bucket of water. An inductive system slowly pours it out over a period of time, where the CDI just tips the bucket over and dumps it all at once.

[futurevr4man]

So I am also an ME (I taught Adam everything he knows ) and some of this is over my head... but I can pull the concepts out from what you all are saying.

It seems the direction we are going is that Jim is going to test some hotwired coils so that conclusions can be made (THANKS again Jim!). But the anticipation is killing me! Do you EE people think that hotwiring the coils:
A) Is a good "fix" for spark blowout/fouling?
B) As good as a BAS/DLI?

I am trying to look ahead at things I need. I consider the BAS/DLI the same thing as a piggyback... it's just one more thing that needs to work just right for the car to do what it's supposed to... adds complication to the system. So I'm just curious, looking ahead, what you guys think

[Chris@Rvengeperformance]

I wish someone would do some electrical testing on the DLI, I've always been skeptical that they work.

[DocWalt]

A)Hot wiring the coils is essentially part of the way to a BAS without the additional complication. If you want more powerful spark (because reduced dwell time as RPM climbs isn't taking away charge time) run a BAS or another voltage regulating device to bump up the voltage to the coils.

B)Stock coils have a much longer ignition pulse than a DLI, so they have an advantage there for "normal" driving. At WOT the DLI is probably better...

I'm not the greatest at technical writing, but c'mon, Brad did a great job of explaining it for you ME's that are confused by electric

[fastbikes76]

It seems the direction we are going is that Jim is going to test some hotwired coils so that conclusions can be made (THANKS again Jim!). But the anticipation is killing me! Do you EE people think that hotwiring the coils:
A) Is a good "fix" for spark blowout/fouling?
B) As good as a BAS/DLI?

I am trying to look ahead at things I need. I consider the BAS/DLI the same thing as a piggyback... it's just one more thing that needs to work just right for the car to do what it's supposed to... adds complication to the system. So I'm just curious, looking ahead, what you guys think

My experiance is as follows...

'somewhere' along the system there is a loss of voltage between what the battery is seeing, and what is actually reaching the coils. Now I too am more mechanically hands on then electrically, but from my tests I found that there was upto 1.5V difference between battery voltage and coil voltage. Then when our alternators get hot they seem to lose another 1 to 1.5V on a WOT pull...the time you need decent spark the most !.

I measured the following on my car

14.4V battery and 12.7 at the coils on idle
13.1V battery on WOT and if you take away the same 1.7V loss that would leave you with roughly 11.4V on WOT.

Yes the hotwire can be seen as a 'band aid' rather than a full on fix for the lost voltage, but then why would you want to tear a harness apart and spend hours/days tracing something that may or may not be found when the hot wire costs 10 bucks, takes an hour tops and WORKS without a doubt.

On my 10;1 engine running 20% in tank methanol I was really struggling at 18psi or more. Tried copper plugs, tried irridium plugs, tried Platinum plugs. I gapped the plugs right down to the point of poor tick over, I replaced leads, PTU, ECU and coil packs. Nothing i tried cured the high boost miss-fire, It's only When Keithmac told me to hot wire the coils like him did i cure the miss fires. It was then I tested for voltage loss (I have 4 GTO's) and they are all fairly similar in terms of lower voltage at the coils.


Its 10 buck, it works...do it




ETA..

you only need to do the hotwire if you have a voltage loss on YOUR car. I guess not all will be suffering this, or maye they are ?
In the hotwire thread there is a test to check in the first post.. http://www.3sgto.org/3000gt-stealth-...twire-diy.html

[familyMAN]

I wish someone would do some electrical testing on the DLI, I've always been skeptical that they work.

It works. I have unplugged it and it's blow-out city, plug it back in and good to go. Now if you mean skeptical on "how it works" I can't answer that, only that it "does work."

[Chris@Rvengeperformance]

It works. I have unplugged it and it's blow-out city, plug it back in and good to go. Now if you mean skeptical on "how it works" I can't answer that, only that it "does work."

Yeah that's my problem with it, I know from a lot of history it works, but with how its wired I don't understand how.

[BaadVR4]

Yeah that's my problem with it, I know from a lot of history it works, but with how its wired I don't understand how.

The DLI simply increases "dwell", the time the coil primary side ground is closed and the associated field on the secondary can build. This greater time for current to flow through the primary side of the coils results in greater voltage and energy available on the secondary side to fire the plug under marginal conditions which need the greater energy to fire.

How this increase in dwell is made to happen is just one of the great mysteries of electrical/electronic magic. If this were a 1969 Road Runner with a distributor, you increase dwell by adjusting the points to stay closed longer. The DLI? only God and his specially selected EE wizards know. And even if they are telling I'm not understanding. Not one of the elect.

[CoopKill]

Whooah! Wait, steve68 is back!