Mint87RX7

I have been having some nasty drivability problems lately. today i hooked it up to an ignition scope (these things aparently were not designed to be hooked up to a 7). The trailing coild looked great, the #1 leading looked kind of odd. It is firing hard on one hit and then a week spark after that and it alternates high,low,high,low. The #2 side has no firing line... Like the plug is not firing at all. I checked all the plug wires and they ohm out good. pulled the plugs and they look normal, seems like if the plug wasnt firing it would just be one big carbon chunk but it looked decent but had a little oil on it(i premix). i tried switching wires and plugs and it didnt change anything. I think the coil is probly dead but I also want to know about the ground, from what i know it grounds through the coil case to the body. is there a seperate ground for #1 and #2? i thought maybe that could cause it but i havent looked into the wiring that much yet. what are your oppinions on the condition of the coil and what should i check on it, i basically have unlimited resources to tools and diagnostic machines. ideas?

RotaryEvolution

iTrader: (30)

try a compression test, the coils don't alternately cut out, the CAS would be the fault but same deal with the sensors in the CAS, they rarely fail and when they do you get all or nothing most often.


something to check though still would be to simply install a plug in the wire and check to see if the spark is erratic.

Mint87RX7

110 compression in all 6. and if it was a bad seal i think it would be every 3rd instead of every other fire being week, it could have just looked weird on the scope because of how you have to hook it up. Im more worried about why the #2 leading isnt firing. and with the CAS, what exactly is it picking up? is there a point for every combustion chamber, including points for trailing? or does the ecu have a lot to do with what fires when?

Mint87RX7

Also, I checked on alldata today for the specs for the coils and there seems to be no way to test the coil without some special diagnostic box they connect to it. is there an easier way to check the coil without taking it to the dealer?

RotaryEvolution

iTrader: (30)

the dealer will be worthless so don't bother. coils are a dime a dozen at the wrecking yard so long as there is a seven there since they hardly ever fail. the CAS is a simple trigger wheel with 2 sensors and 2 firing tabs per rotation, the leading sensor controls the leading coils and the trailing sensor controls the trailing, pop the cover off the CAS(2 phillips screws) and check the condition of the triangular firing pointers on the shaft, if one is damaged, corroded or rusted it could be affecting the signal for the signal for the snd leading coil firing position but this will not cause a weak ignition pulse it would cause a fine one or none at all, you said it was weak correct?

HAILERS

Lead 1 cannot fire without Lead 2 firing and vice versa.

I suggest if your using a timing light to reverse the clamp on the Lead wire that is firing irregular.

Go back to ALLDATA and look at the field service bulletins that address the timing light issues.

RotaryEvolution

iTrader: (30)

he said he was using an oscilloscope but i still find them to be relatively useless in these cars since the spark is nowhere near comparable to a piston engines ignition system with the weak trailing output and odd shaped spark plugs.

i still recommend just popping in a spare plug and testing spark visually with it at all 4 wires, if there is spark there is fire and you're looking in the wrong area for your problem..

you did install new spark plugs correct? they are the correct one right? BUR7EQ leadings and BUR9EQ trailing for stock or lightly modded engines.

Mint87RX7

Im using a sun machine ignition scope to see everything so i can see the entire spark line. there is no visible spark or any voltage jump. Its a realy weird display, like something is wrong other than the coil. and hailers do you have any details on why #1 cant fire if #2 isnt?
and about the #1 having a weak every other spark, is it possible that it is firing on both the #1 and #2 signal? not sure how it could get crossed but i cant think of an explanation for the weird pattern.
edit: I havent done a visual on it and im going to try it tomorrow, and they are new plugs.

RotaryEvolution

iTrader: (30)

the spark test will answer your questions and takes abour 2 minutes to do, alot quicker than us trying to figure out what is going on, more than likely it is perfectly fine. as i said these ignition systems are fairly unreliable when using them on an oscilloscope or when testing with a timing light.

Mint87RX7

do you happen to know if there are 2 seperate grounds for it? i think there are 4 bolts, are 2 for #1 and 2 for #2?
and once i figured out how to hook it up, there was a realy good display on the scope. the voltages arent that high but you just change the scale and its perfect. and the trailing voltages are way higher than leading, probly because by the time they fire its kind of like having a lean mix

RETed

Ignition scope?
Are you using an inductive pick-up?


-Ted

Aaron Cake

iTrader: (1)

Beat me to it.

To elaborate, the leading coil pack is just one coil. One spark plug connects to one side of the oil, the other plug to the opposite side. So if one fires, then both must fire. It's impossible for it to be "half dead".

HAILERS

Here's an interesting thread on the ignition from the other site: http://www.teamfc3s.org/info/articles/demystifying.html

Mint87RX7

Ted, Its like an elaborate multimeter on a pc system. I am using inductive pickups to display the spark patterns, here the site to see basically the same system- http://www.sun-diagnostics.com/catal...1&item_id=3470
the only explenation i can come up with right now is that if this is a normal waste spark ignition (leading side) then somehow the voltage is not going in a loop through the plugs back to the coil, like its somehow connected to ground and just bypassing the #2 plug/wire. if you have any ideas on what i should check today besides the cas, please post up cuz im going to the shop in an hour.

RotaryEvolution

iTrader: (30)

i think you would be better off posting symptoms for us to help you diagnose.

HAILERS

http://www.teamfc3s.org/info/articles/demystifying.html

Those PC based systems seem to be muliplying. Like this one: http://www.picotech.com/

I have none.

RETed

8<

I only ask, cause inductive pick-up's are not reliable on the stock FC ignition system.


-Ted

Whizbang

ill throw in my problem too seeing its related. My leading coil might be dead as well. but it either works or doesnt. getting worse all the time. I think just the trailing coil is keeping the car running. It idles no problem. little rough and rich smelling. sounds like its missing. But idles decent. But if you use the accelerator to rev it, hit reaches about 2k before falling. cant be driven while its doing this.

HAILERS

Swap Lead plug wires and see if the problem travels. OR just move the L1 to L2 at the coil and see if the problem travels.

Whizbang

wont that mess with the timing of the ignition? this problem comes and goes. or are we testing to see if the coil is shorting internally.

HAILERS

I don't understand. Why don't your, while the engine is running, pull one of the lead wires out of the lead coil bore and see if it's arcing or not????? Five minutes and you know more than your guessing at now.

It kinda sounds like the trails are doing all the work though. Just guessing.

Whizbang

...good idea....

HAILERS

This was directed at the thread author.

RETed

Yep, that's what I was wondering too.
It's a lot cheaper and quicker to diagnose this way.


-Ted

KingCobraV9

iTrader: (2)

well i went to the mazda delalership in town and they said a new trailing coil pack it $998.50 from mazda new. so i would go there.



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