Weird Starting Problem, Already Tried The Basics

[mulcy]

My 94 NA is giving me fits trying to figure out this starting problem. I've narrowed it down to a problem with spark (starter and fuel pressure are fine). If I attach a plug wire and spark plug to the ignition coil and crank the engine I don't see any spark for a while, then I'll see a few in a row, then back to no spark. You get the idea - intermittent spark at the coil when cranking. Eventually I can usually get it to start and once started it runs fine.

So far I've switched out the cam and crank position sensors with other sensors that are known good. I've also switched out the ignition coil and there was no change.

The next things on my list are the ignition switch and the PNP switch. Which do you think is more likely the problem? I don't want to buy any parts that I don't have to... I'm leaning towards the ignition switch since everything works fine once the car is running.

Only codes are A1 114 (Program selector open circuit or short circuit to supply) and A1 124 (Mode selector faulty or short circuit to ground). I've cleared them and will see if they come back. These are the reasons I'm also considering the PNP switch.

[volvoskiah]

have you tried a different ignition coil?

[drin850]

So far I've switched out the cam and crank position sensors with other sensors that are known good. I've also switched out the ignition coil and there was no change.

have you tried a different ignition coil?

Have you ever changed the cap and rotor? wires? plugs? these items are pretty cheap (from IPD or FCP)and a good idea to get out of the way if you havent already.

not having the spark plug grounded properly while testing for spark may be why you only notice a few inconsistant sparks.

[mulcy]

yep, cap/rotor/wires/plugs have all been changed recently and are good.

[Matts 850 GLT]

When it's cranking does the rev counter move?

Matt

[850newb]

my dollar is on the ignition switch, every so often I get a no-start while cranking and I believe it's tied to the power feed to something important. Once it starts it's fine for a week or so before it happens again, gotta remember to throw the test light in the back seat.

[mulcy]

So after removing the steering column covers and messing with the ignition switch the car is starting better. I still see intermittent spark at the coil when cranking but it's working well enough to start the car after a few seconds (as opposed to taking minutes as it did before). Guess it's time to track down a good ignition switch.

[troyhyde]

In addition to the ignition switch, might pop a different alarm relay in there. It can cause an intermittent weak power supply to the starter (acts like a dead battery). I suspect it will make the spark fiddly but don't know for an absolute fact.

It's up under the driver's floorboard area and easy to swap.

[mulcy]

So it's not the ignition switch after all. I picked up another one from a junk yard and there was no change - it still takes an inordinate amount of cranking to get the car started.

I checked the codes after swapping out the ignition switch and the cam sensor code (314) is back on despite swapping in a known good sensor only a week ago. When I swapped the sensor out I noticed some oil leakage from the rear exhaust cam seal. My new theory is that oil is gumming up the sensors, giving an intermittent signal and causing the hard starting even with a basically new sensor. Sound reasonable? It's probably time for a PCV job and new cam seals on the old beater.