If you truly have spark at the coil but not at the plug about the only thing that can happen is the rotor has a hole burnt through it. It will appear as a dark spot. That or moisture inside your cap or a shorted coil to dist wire with the spark jumping out of the wire.
[This message has been edited by phonedawgz (edited 12-13-2013).]
When dealing with high voltage an ohm meter is only somewhat helpful. The ohm meter measures the resistance at a very low voltage. The spark operates at a high voltage. So lets say there is a micro-hole in the rotor. Because there is an air gap between the metal of the rotor and the dist shaft the ohm meter will read infinite ohms. But the spark will still jump to ground there.
When the ICM fires the coil the voltage in the coil will build until it finds a place where it can jump to ground. If you check for spark by holding the wire away from the block the voltage will increase the farther the wire is from the block. So perhaps your testing procedure is changing as you change from the coil to the spark plug. Note also - a spark plug installed in a cylinder will need even much higher voltage to fire. So if you are testing by using a timing light and you are't getting a spark with the wire connected to the plug but you can get a spark outside the cylinder that is because inside the compressed cylinder more voltage is needed. So bad insulation in the coil can give you an situation where you can get spark outside the cylinder but when connected to a plug, the higher voltage needed is above the defect in the coil and you no longer get a spark.
... inside the compressed cylinder more voltage is needed. So bad insulation in the coil can give you an situation where you can get spark outside the cylinder but when connected to a plug, the higher voltage needed is above the defect in the coil and you no longer get a spark.
I was taught a long time ago that the spark needed to be strong enough to jump a 1/4" gap outside the cylinder.
its on the new style distributor with star points instead of the fingers like the old design. so it shouldn't be that old.
just did a quick read, I saw on the msd website that a pick up should be measuring about 500-700 ohms if good. will check to make sure.
Im almost positive now its the cap and rotor. but the guy Im doing the work for wants me to go through THE WHOLE checklist before he opens up his wallet.
[This message has been edited by AL87 (edited 12-16-2013).]
okay, so replaced the cap and rotor, getting spark to the plugs now. checked fuel pressure at 43psi leakdown was down to 40 in 5min and stayed there for another 5min.
fuses are all good. (namely the injector fuses.)
I checked 12V with a test light on the injector harness and this is what I got.
Pink/White: 12v key on/constant green: nothing even when cranking blue: nothing even when cranking Pink: 12v Key on/constant purple/white: 12V when cranking only Tan: nothing even when cranking
I'm assuming What im seeing by the above test is that one of the banks isn't receiving signal.
where to check next? the harness hub by the battery looks suspect of some possible bad wiring, but I don't think that's a problem
i think its the ecm or a broke wire, I would like someone to confirm on what my reads were for the wiring harness to the injectors.
I think i'll just run a new wire to get her fired up but I'm concerned about the wire routing, if the wires going to the injectors go through anything else. ex relays, sensors, senders, etc.
I'm just going to do a voltage signal test at the ecm for the injector bank that isn't firing, if I have signal, then I know there's a break.
either that or an ohms test on the wire to check for a break or high resistance, I'll probably do both. since one tests the wire, and one the ecm signal to the injector bank.
idk, like magic this car started to get signal to where it needed. the electrical system checked out. I guess the pins needed to get cleaned.
decided to recheck everything. and it was good. it turns out the plugs were rusted so bad, the ground wasn't good enough to jump the spark on the firewall side.
yeah, pretty much. I pulled the related connectors and re-seated them. and all of a sudden I had signal to the injector bank that wasn't getting any. everything checked out fine after that, so I checked the last thing after the electrical issue was solved, which was the plugs. changed them all out at the proper gap and then she fired right up, timing was off so I re-set that, and now she's nice and healthy.
