ok so i set up my lt8 a while back using silverrotor's base map (thanks) and it all worke well except for the dwell value was way off. In the manual it says not to adjust the dwell at all, but i had to to make my car run. so what does this value actually do, and could i have something hooked up wrong that makes mine different?

thanks
pat

 

Basically he Dwell feature is to set how long your coils have to recharge for spark. There should be two modes, DUTY CYCLE and TIME BASE. Duty cycle gives the coils a percentage of the time between firings. Time Base gives the coils a set constant amount of time. Of course all of this is in mS.

 

ok so wouldnt a bigger value just be better? I mean...the stock map that i got had the dwell set at 3 in duty mode. which is 3%, right...so wouldnt you just want 100% so that you have the strongest spark possible? and why isnt it supposed to be adjusted?

thanks for the info

pat

 

Hmmmm. That's a good question, I'm not absolutely sure. But, I think that you have to have time inbetween the charge and the fire. I'm running an LTX12, and I haven't had a chance to see what the stock setting is, but I'm sure i need more time for charge with the Bosch coils.

However, you definately dont want to over charge the coil because that might lead to an early fire or it might damage the coil. Anyway, if i can find any extensive documentation on this i'll send it your way.

Robert

 

In my experience, the dwell should be set to 3.00 if using stock coils, and 3.25 is using Bosch coils.

 

3% or 3ms? becasue im running duty cycle, and my car doesnt run at 3.00.

so should i switch to time base and run 3ms?

pat

 

Please elaborate on this. I just got my car running and I have the stock dwell time at 3.00 but I'm using the Bosch coils. What effect will it have if I change dwell to 3.25?

Thanks for the advice.

 

I would also like to know this. I JUST got my car running after installing my LTX12 and have yet to properly tune it. And this is something that to me is critical.

Patman. It is my understanding that with rotaries you have to run duty cycle because of how the timing changes....so you can't set a constant time because it could throw everything off. I'm not positive on this, but to me at least it makes sense.

Just my 2 cents.

Robert

 

well...im going to switch mine to time base...the map that i set the car up with was set to time base i just found out. since it is supposed to be a map straight from microtech, i assume that thats how it should be.

surfpac, its 3.25 for bosch coils because they are a bigger coil then stock and take a bit longer to charge up. if you leave it at 3.0, you wont really be any better off than if u ran stock coils as the extra charge capacity is the advantage of those coils.

pat

 

Thanks for the explanation, it makes sense. Will take your advice.

 

I happened to know a friend on the other ecu...I think it's a haltech..using dwell time as high as 5.5ms without any issue at all on the stock coils and ignitor. Is this the same millisecond as in microtech?

 

If you're using stock coils, it needs to be fired under "TIME BASE".
If it's under "DUTY CYCLE", you can kill the coil.

The problem with jacking up the TIME BASE duration is that you risk overheating the coil.
So the "perfect" setting is the lowest TIME BASE duration that the ignition will not misfire all the way up to redline and under max boost.

At a certain point, you do not get any performance having a longer TIME BASE duration - the excessive charge times just heats the coil up unnecessarily.


-Ted

 

Try these settings:
Dwel Typel= Time
Dwell= 2.75-3.0 ms
pump Dwell= 3.50 ms

5.5ms on stock coils seems high and it may cause problems later on.

 

if you have it set to 5.5, just go for a 5 minute drive, stop, get out, open the hood and feel the coils. if 5.5 is overcharging them, they will be hot. if they are cool, then youre fine.

pat

 

The 5.5ms settings was for a Haltech.
It looks like the settings are slightly different for the different brands of EMS'.
Haltech's like a 4.0ms to 5.0ms charge time.
5.5ms is a little high but not surprising.


-Ted