 Ignition help...Andy, Mark and I stumped :), not typical problem...Link EFI |
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| Mueller |
 Aug 7 2005, 07:58 PM
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#1
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914 Freak!  Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None 
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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...... Attached image(s) 
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| bd1308 |
Aug 7 2005, 08:20 PM
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#2
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Sir Post-a-lot Group: Members Posts: 8,020 Joined: 24-January 05 From: Louisville,KY Member No.: 3,501 |
spark scatter? what's that?
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| MecGen |
Aug 7 2005, 08:26 PM
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#3
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8 Easy Steps Group: Members Posts: 848 Joined: 8-January 05 From: Laval, Canada Member No.: 3,421 |
Hi Mike
Since I don't know what type ign you are running (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) 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 (IMG:http://www.914world.com/bbs2/html/emoticons/unsure.gif) This is good for a (IMG:http://www.914world.com/bbs2/html/emoticons/icon_bump.gif) Later |
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| bd1308 |
Aug 7 2005, 08:27 PM
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#4
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Sir Post-a-lot Group: Members Posts: 8,020 Joined: 24-January 05 From: Louisville,KY Member No.: 3,501 |
link EFI
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| lapuwali |
Aug 7 2005, 08:31 PM
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#5
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Not another one! Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743  |
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) |
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| McMark |
Aug 7 2005, 08:58 PM
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#6
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
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. |
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| bd1308 |
Aug 7 2005, 08:58 PM
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#7
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Sir Post-a-lot Group: Members Posts: 8,020 Joined: 24-January 05 From: Louisville,KY Member No.: 3,501 |
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. |
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| SirAndy |
Aug 7 2005, 09:03 PM
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Resident German Group: Admin Posts: 41,669 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
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! (IMG:http://www.914world.com/bbs2/html/emoticons/cool_shades.gif) Andy |
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| Dr Evil |
Aug 7 2005, 09:04 PM
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Send me your transmission! Group: Members Posts: 23,002 Joined: 21-November 03 From: Loveland, OH 45140 Member No.: 1,372 Region Association: MidAtlantic Region
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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?
(IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif) |
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| DNHunt |
Aug 7 2005, 09:08 PM
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914 Wizard? No way. I got too much to learn. Group: Members Posts: 4,099 Joined: 21-April 03 From: Gig Harbor, WA Member No.: 598 |
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. (IMG:http://www.914world.com/bbs2/html/emoticons/ar15.gif) Dave |
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| Trekkor |
Aug 7 2005, 09:09 PM
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#11
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I do things... Group: Members Posts: 7,809 Joined: 2-December 03 From: Napa, Ca Member No.: 1,413 Region Association: Northern California |
Uhhh...try carbs (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)
Sorry...I'm no help. KT
All the bug aftermarket guys have those...For the 009. (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif) Again, I'm no good. Bad me, bad me. (IMG:http://www.914world.com/bbs2/html/emoticons/spank.gif) |
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| SirAndy |
Aug 7 2005, 09:09 PM
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#12
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Resident German Group: Admin Posts: 41,669 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
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 ... (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) Andy |
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| McMark |
Aug 7 2005, 09:10 PM
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#13
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
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. (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) |
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| SLITS |
Aug 7 2005, 09:12 PM
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"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None |
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. |
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| bd1308 |
Aug 7 2005, 09:53 PM
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#15
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Sir Post-a-lot Group: Members Posts: 8,020 Joined: 24-January 05 From: Louisville,KY Member No.: 3,501 |
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. |
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| Engman |
Aug 7 2005, 10:11 PM
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#16
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Zoisite Group: Benefactors Posts: 1,349 Joined: 25-March 03 From: New Albany, IN Member No.: 475 |
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 |
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| Mueller |
Aug 7 2005, 10:28 PM
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#17
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None
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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. |
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| Brett W |
Aug 7 2005, 10:35 PM
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#18
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Advanced Member Group: Members Posts: 2,856 Joined: 17-September 03 From: huntsville, al Member No.: 1,169 Region Association: None
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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.
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| Mueller |
Aug 7 2005, 10:55 PM
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#19
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None
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I'm getting the pickup from the Mallory distributor, it is locked, no mechanical advance at all. |
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| Aaron Cox |
Aug 8 2005, 12:02 AM
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#20
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Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
wow.....sorry to hear of your troubles....
would this have been an easier install with crank fire? |
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