on my 1990 GXL the leading coil/ignitor is done but the connector to it gets voltage when i hook up a VOM and turn the engine by hand. now it starts kinda slow, runs decent, and idles most of the time good. but when i depress the clutch to stop at a stoplight or somthing the rpms drop to ~500 or so and somtimes dies, also if let it idle for ~10 min the rpms start to jump evenly ~200 rpms. i replaced every vac line, the intake mani to LIM gasket, LIM to UIM gasket, the UIM to dynamic chamber gasket, and the o-ring that fits on the front of the TB, and checked for vac leaks 2 times with propane, so its not that. will that coil being replaced fix this problem? well ill find out soon, my gut says the coil is bad not the ignitor, but i could be very wrong, and theese coils are not remotely cheap at all!
any help will be appreciated.

 

Mine did the same exact thing it dropped when i depressed the clutch, i adjusted my tps and i was good to go

 

ok, could the bouncing idle be the TPS also?

 

Yes it could.

 

just to help me understand, the trailing coil does most of the work right? so how does the leading coil help out, and when?
i have some ideas, but their probably wrong.

 

Trail coil does close to nothing.

Lead coil is vital.

 

It's actually the opposite. The trailing coil helps to ignite the fuel left over which failed to ignite by the leading coil. The car should start and run with just the leading coil.

 

no
the trailing does FA and essentially is there to help burn residual mixture forced to the end of the chamber after the leading ignition main bang
trailing coil does not work during cranking when the ECU is in a "non sequential" mode

disconnect the clutch switch and see if problem persists with clutch in
if no,,, issue is electrical
if yes then the issue is mechanical
if the engine stalls with the load from the thrust bearing ( clutch in )
then thrust bearing may be seized
or the endfloat bad
or the compression very poor

 

Gee whiz golly........I don't believe that at all. The Trail coil works just fine when your starting the car. I'll agree it (trail coils) do little to nothing to aid starting, but the suckers do fire while starting the car.

 

ok thanx, ill try that.

 

then why will my car start, run, and drive 10+ miles fine with the leading coil not even in the car?
I've only driven once for 10+ miles and haven't driven since

 

You can operate the car w/o the leading coil but the engine will usually run rougher and in a less efficient manner such that emissions and gas mileage would likely suffer.

 

oh, ok
ya it seems that it should have more to give and is a little rough, but it passed emissions fine when I bought it ( I made the seller take it with me to a emissions station) but I guess the coil kraped out after that.

 

is there a way to test if the ignitor is good/and if the coil is good, because according to mazdatrix it's 400+ for a coil and ignitor?

 

If you call only the trail coil working fine...............then your going to be really happy when the LEAD coil assy finally gets working. I'd never leave the house if only the Trail coil assy worked. Not worth the trouble.

If I had to pass a emissions test I might try a car that had only the Lead coil assy working...........but if the trail was the only one working, I wouldn't even try. So you get a A plus for passing with just the trail working.

Lead coil assy is near the battery.............just wrote that in case there's a case of mistaken identity here.

Trail coil assy's fire when your cranking the car and can be proven by just lookiing at the tach needle do little bounces as you crank. Tack works off a firing event by the trail coil assys and if there's no bounce of the tach needle...then the trail coil assy's are not firing.

For all practical reasons the ignitor can't be checked out unless you have the Mazda tools shown in the jpg attached. The coil can be checked more or less using the method shown in the attached jpg out of the Engine Electrical section of the FSM.

It's almost a given the lead coil is getting power 'cause your trail coils are working and they both get the power from the same source (black/yellow wire in the small white plug attached to the assy.)

Whether it's a lead or a trail coil assy..................the assy must make contact with the chassis with at least one hold down stud. The ignitor gets it's ground circuit from that contact. Lay a lead or trail coil assy on a sack of rags and they will not, cannot work at all.

 

There is a ghetto way to check the igniter with a 12v capacitor, but I don't recommend it.