Static timed at 10°, no mechanical advace, the ECU controls spark (the ECU does not add advance from 0 rpm to 500 rpm)

Car starts up fine, once I get the revs to 2500 I get spark scatter...we cut a hole in the dizzy cap and confirmed this

In the picture, the rotor turns clockwise.

White marks are open windows for the trigger, red mark is the trigger....black marks on the body of the dizzy are the locations of the leads for the sparkplugs.

I changed the location of the LED (red mark) and it did not seem to help at all......

spark scatter? what's that?

Hi Mike

Since I don't know what type ign you are running

But hi RPM ignition misefires are usually coil saturation related. And I imagine you checked the air gap of the optic or hall effect sensor ?

If you are running a multispark.... thats a another can of worms

This is good for a

Later

link EFI

Are you still firing the ignition through an MSD/Mallory CDI? How bad is the scatter?

Seems you've had an awful lot of trouble with the ignition side of this system. Is the optical pickup their setup, or yours?

My wild guess would be you simply have a noisy tach signal, which is a problem you've had before (and a problem you had with MS, too). Does the Link do any datalogging? If so, perhaps you can watch the tach input to see if it spikes. If not, you're going to have to borrow a scope from someplace. Something in that car is generating a lot of noise.

(spark scatter, bd, is when the spark starts to jump around rather than remain where the timing says it should be)

We really were stumped. The problem seems to be that the rotor on the Mallory distributor appears to have passed the HT Lead terminal by the time it fires. The trigger window passes only about 8 degrees before the rotor sweeps past the HT terminal. Sooooooo, unless the LINK EMS is waiting 90 degrees before firing the plug, we don't see how it can get more than 8 degrees advance without making the spark jump huge distances (read: spark scatter). We looked at Andy's MSD distributor and their "points" triggers are 45 degrees off of where the rotor points. So there's plenty of room for advance.

We spent about 1.5 hours just trying to rationalize why, even with the static timing set at 10 degrees and the ignition table zeroed, we were getting spark scatter. I'm still not confident I really understand the problem.

so the timing becomes erratic, like when i rev my car at 3500 and try to time it EXACT to the dot....


it always shifts in small variation liek crazy.

today was simply too hot. 105 in the shade. brain not worky. need ... cold .... air ...

today got me thinking, does anybody make transparent dizzy caps? it kind of sucks that you have to cut holes in yours to see the " spark scatter".
and what a lightshow it was!

ok, how about cutting 4 windows with a tapered edge and super-glue in some plexiglas?
i'd love to see what's going on inside my dizzy!
Andy

I may not be grasping at exactly what you are experiencing, but just wondering IF it is an optical trigger unit (you did say LED, right?) then is it possible that the lights from the sparks are triggering them selves at higher RPM?

Mike

How hard would it be to add a pot in the tach signal to the ECU? I think James is right about the noisy tach in. Also shield the SOB.

Dave

Uhhh...try carbs



Sorry...I'm no help.

KT

QUOTE

transparent dizzy caps

All the bug aftermarket guys have those...For the 009.

Again, I'm no good. Bad me, bad me.

QUOTE (Dr Evil @ Aug 7 2005, 08:04 PM)

but just wondering IF it is an optical trigger unit (you did say LED, right?) then is it possible that the lights from the sparks are triggering them selves at higher RPM?

i don't think so. the spark(s) is at the top of the black divider, the sensor is underneath and they're shielded from each other ...

Andy

If you look at the picture that Mueller posted, the optical trigger is shielded from spark light by the part that has the white marks on it.

So, no, not possible, but good thinking.

We had a problem on the race car with scatter. Turned out that I had not put a resistor in line with the coil to drop the voltage and the resulting spark energy in the cap was triggering the led (crane/allison led unit).

Cut a piece of heavy paper, painted it black and put it under the rotor.....problem solved

dropped the voltage to the coil after that.

QUOTE (SirAndy @ Aug 7 2005, 09:03 PM)

today was simply too hot. 105 in the shade. brain not worky. need ... cold .... air ... today got me thinking, does anybody make transparent dizzy caps? it kind of sucks that you have to cut holes in yours to see the " spark scatter". and what a lightshow it was! ok, how about cutting 4 windows with a tapered edge and super-glue in some plexiglas? i'd love to see what's going on inside my dizzy! Andy

i've seen them made for type4s.....

do a google on transparent distributor caps VW or something

i know ive seen em...

clear, blue and red colors.

Not sure where you are picking up the trigger signal but I suspect you have same noise in the trigger. Hook up an osilliscope to it to see if that is the case.

M

the car idles and runs just beautiful right up to 2500, basicly anything over 2500 and the HT lead is too far from the rotor...when too far, the spark cannot jump the distance.

I'll be sending the picture to Link in the morning and then calling them, I have the feeling it has something to to do with the trigger windows (white marks) relative to the end of the rotor electrode.

I think if I close the existing "windows" and create 4 new ones X-degrees, then I'll be okay.

Where is your pick up reading from? If you are reading from the factory dizzy did you lock out the factory advance mechanism? Since the computer controls the timing there is no need for the dizzy to do anything but rotate. Lock the advance plate out and it should be good.

QUOTE (Brett W @ Aug 7 2005, 09:35 PM)

Where is your pick up reading from? If you are reading from the factory dizzy did you lock out the factory advance mechanism? Since the computer controls the timing there is no need for the dizzy to do anything but rotate. Lock the advance plate out and it should be good.

I'm getting the pickup from the Mallory distributor, it is locked, no mechanical advance at all.

wow.....sorry to hear of your troubles....

would this have been an easier install with crank fire?

Mike – I’ve been pondering the same issue. I’m going to be controlling ignition and fuel using Megasquirt 2, also with a Mallory Unilite. I looked at the distributor rotor and wondered if it would allow enough advance without encountering the spark scattering that you’re seeing. I’ve seen other rotors that have a contact similar to the picture below. Since this is removable/replaceable, I’ve wondered if the standard contact could be replaced with something like this, and if it would solve the problem?

I have not tried it yet, but I'm 99% sure this method here will get me going in the correct direction......luckly from doing research on FI systems, I have come to find out just how close each system is to each other.....(it's scary, how many of them are very, very similar...can you say reverse engineered or engineers that have jumped ship to start thier own company??? )

I'm using a Link EFI, these instructions are from Haltech (yes, Link does have instructions, but I think they are "lacking" or at least to someone with a pea-sized brain like me )

Anyways, for those following along at home, this how it's done.....

QUOTE (gklinger @ Aug 8 2005, 08:25 AM)

Mike – I’ve been pondering the same issue.  I’m going to be controlling ignition and fuel using Megasquirt 2, also with a Mallory Unilite.  I looked at the distributor rotor and wondered if it would allow enough advance without encountering the spark scattering that you’re seeing.  I’ve seen other rotors that have a contact similar to the picture below.  Since this is removable/replaceable, I’ve wondered if the standard contact could be replaced with something like this, and if it would solve the problem?

yes Garry, I did make a new "tip" (solid brass door hinge was the donor material.... )

I love it when I'm right.

Just wait till I e-mail Link (a New Zealand company) to tell them I had to get help from Haltech (an Australian company)...they'll love that, hahahahaha


correct Mark, I thought so too, but the lack of me seeing it in the f'n manual made me think otherwise....

We all agreed that was the problem, we were all right.

glad i could help!

Andy

QUOTE (SirAndy @ Aug 11 2005, 07:42 PM)

glad i could help! Andy

yea...thanks for drinking all my ice teas and sodas, couldn't have done it without you

just kidding

I'm telling you, next time you come over you gotta try the Jones Soda Chocolate Fudge Soda...taste like liquid tootsie roll.....

update for those that care

Andy came by yesterday and we played with the ignition again....upon letting him read the install directions, I think Mark and I had been interpreting it incorrectly.....

Andy believes (and it makes sense now) that at 0-500rpms, the trigger event is supposed to happen at 10° BTDC...at this time, we get a spark event...now once the RPMs go past 500 rpms, the trigger event does not fire instantly, but instead waits 90° (or there abouts) to fire the next cylinder the specified about of advance....so if I wanted 20°, the Link would wait 80° before firing.