Whisper

Was setting timing the other day, and noticed that both leading and trailing are missing fairly consistently. It looks like the timing light is blinking now and then, and every time it blinks, the motor misfires. Every miss is significant enough that it causes the engine and the car to jerk. Revving it up doesn't seem to clear it either. I think it's causing the vibration I'm getting when driving.

Spark plugs don't appear fouled. Put in a spare set that's pretty much new and it doesn't seem to make a difference.

Wires are brand new.

Since it fires, I'm assuming igniters must be ok. As I understand there's no "starting to go bad"condition for them - they either work or they don't. BTW, which igniter is the leading and which is the trailing?

Trailing coil is original, but I'm using 2nd gen coil for leading. If it were just the leading or the trailing, I'd prescribe it to one of the coils...but when it's both, it seems unlikely.

I just pulled the distributor and checked the air gap, and it's within spec. I'm not sure how much play there should be in the shaft, but whatever minor play is there doesn't affect the gap.

Cap is new.

Rotor has some rust in the shaft housing (I'll be buying a new one), but other than that I doubt it's the culprit, especially since I'm bypassing cap and rotor with the 2nd gen coil for the leading.

Now, the compression in the rotors is a bit uneven, both rotors have one face where compression is lower, but still above minimum spec. I don't know if that would cause a miss. It would probably cause a shake, though.

Finally, this may or may not be relevant, but there's a leak in the exhaust (back end of the main cat, I think). I'm saving up for new exhaust right now.

What are some basic things I can do to troubleshoot this issue further?

Starfox07

I also have an exhaust leak (or several) and I don't have any sort of miss because of it. Sorry if that's the only thing I can offer. The elders will swarm shortly I'm sure.

74RX4

iTrader: (10)

Front ignitor is leading. Side is trailing. Check your engine compartment at night. Make sure none of the plug wires or coils are arcing.

Sgt.Stinkfist

iTrader: (6)

honestly, if you dont mind a little jolt just put your left hand on the chassis and lightly run your right hand across the coil and plug wires... its not that bad. you could also lightly mist the ignition components w/ a spray bottle w/ water and see if the car starts running worse and/or little blue arcs start to show up.

Rx-7Doctor

iTrader: (13)

Check the connections at the ignitors to ensure they are tight.

Have you performed a fuel quantity/pressure test?

Did this issue come on all of a sudden or have you noticed it and it's getting worse?

Is the fuel tank full or near empty?

Whisper

Stinkfist: It's possible the spark is jumping or something. I'll try those methods.

Doc: Ignitor connections are tight, and I've cleaned the connectors to the best of my ability. Haven't done quantity/pressure test, but had my injectors fully serviced and replaced fuel filter. Issue was there before, when I bought the car, but was ever so subtle. After I spent some time working on the car, cleaning and replacing stuff, adjusting everything to spec, issue got progressively worse. I think it was bad before, but the settings were fiddled with in such a way as to mask/band-aid the problem (for example the timing was way advanced, among other things). Fuel tank is about 3/4 full. It does it even when it's completely full, or almost empty.