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Eric

RE: Dwell Help

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Hi Im going to install the msd dis-2 on my car. Can you help me about the dwell values please. Please note the cars have also msd coil pack and running at 11000 RPM.

Thanks in advance for your help.

Eric

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Hi Eric,

A good starting point would be 3ms dwell right across the table. When you are testing it watch the dwell value in the runtime values and make sure it is not being reduced at high RPM.

Cheers,

Scott

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Hi Eric, 

In this situation there are two important time constraints when it comes to ignition. Spark duration (normally somewhere around 1 ms) and dwell. As RPM increases there is less time for both functions to be performed. On the Link G4 systems when there is not enough time for both, the spark duration remains constant and the dwell time is reduced.

The only things that can be changed to improve this is to modify the ignition system or make compromises on dwell, spark duration or RPM.

I am unsure whether the MSD coil pack you have is direct spark or wasted spark.

Assuming it is running waste fire coils, spark duration of 1ms and dwell of 3ms, each ignition coil will fire every 360 degrees, which means the maximum rpm is 15,000 rpm.

It looks like you will be fine, usually when people run into this problem it it trying to run something like a single coil distributed v8.

Cheers,

Scott

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This is the information about the coil

Coil Wire Attachment Female/Socket
Coil Style Coil pack
Primary Resistance 0.530 ohms
Coil Internal Construction Epoxy
Coil Color Red
Maximum Voltage 40,000 V
Turns Ratio 83:1
Secondary Resistance 12.8 ohms
Inductance 5.8 mH
Mounting Bracket Included No
Coil Wire Included No
Ballast Resistor Included No
Coil Shape Square
Height (in) 3.349 in.
Length (in) 4.097 in.
Width (in) 3.472 in.
Quantity Sold individually.
Notes For DIS ignitions.

Now how i shall for the ignition mode as mine is set on Wasted spark.

Spark Edge ( Is set as Falling)

Ignition Delay ( Is set 0 us)

Spark duration ( Is set to 1 ms)

Max Advance ( Is set 45deg BTDC)

Thank again for your help as this car is making me crazy

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Hi Eric,

What is actually happening? Is the engine running at all? Or are you only having problems at high RPM?

Do you have a photo of your ignition coils or a link to a website where I can find information about them?

I need to try and find out if your coils one one per cylinder, or if they are wasted spark.

Cheers,

Scott.

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Hi Eric,

Thanks for the links. The ignition coil only has two inputs, so must be operating in a wasted spark setup.

Looking at the wiring diagram in the instructions for part number 8241 you will need some a 2 channel ignitor. Do you have on these in your setup.

What is the actual problem? Are you getting any spark?

Regards,

Scott

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Hi Scott,

              I was to have the link ignitor but I use to have like a limiter at about 7500 rpm. So I change it to the msd DIS 2. Yes I use to have spark but it was very low.

So Shall I leave all the following figers as there are?

Spark Edge ( Is set as Falling)

Ignition Delay ( Is set 0 us)

Spark duration ( Is set to 1 ms)

Max Advance ( Is set 45deg BTDC)

Thanks

Eric

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