intermittent spark problem...

[sasquatch]

hey, my friends festiva is having a problem... sometimes it will start and other times it wont, and i have figgured out that it is spark related, when it dosnt start ill hook up the timing light and ill get nothing... then it will start up fine after letting it sit for some time or if we jump start it with another car... we have tried a new battery but that didnt help at all... i have replaced the spark plugs, wires, cap and rotor and all the did was make it run smoother when it does start up... we have also tried a new coil and igniter, but that didnt help... the only things left i can think of are the dist and computer/ecu... is there anything that im over looking?

[JohnGunn]

This mode of failure makes me suspect the failure of some electrical component which is experiencing a heat related failure. Are the times when the engine fails to start usually when the engine is hot? And could the time you must wait until it starts again be time for the engine to cool down?

I don't know what your engine is, but one such component is located in the distributor of a stock fuel injected Festiva, the Crankshaft Position Sensor. If you could get to it by removing the distributor cap, I would try spraying it with some cooling liquid, such as BrakeKleen or starting fluid, when it refuses to start to see how that might affect its operation.

The output of the CPS is what the computer uses to tell it when to send the firing signal to the igniter. If that stopped working you would get no spark. It might even be enough to just spray the exterior of the distributor to affect its performance.

Otherwise, you could swap out the distributor with a know good one as a test.

One last thought. You might also want to check the connection at the distributor that carries the output of the CPS to the computer. Especially if there is no observable relationship between the heat of the engine and the failure.

John Gunn
Coronado, CA

[econoaddict]

This I would try spraying it with some cooling liquid, such as BrakeKleen or starting fluid, when it refuses to start to see how that might affect its operation.

I would ensure that what ever you use is NON-FLAMMABLE, just incase you get a spark.

Also brakecleen can have bad effects on plastic parts as well as the insulation that is inside electrical components, if it's not bad now it very well could be after you spray it.

Why not just use air to cool it??

[WmWatt]

If the engine turns over the battery should not be the problem.

Intermittent starting and stalling is a symptom of a dying ignition control module (ICM).
The ICM can be removed and taken to some auto parts stores to be tested for free.
If you replace the ICM you should bed the replacement in dielectric heat transfer paste which can be bought in little capsules from electronics stores for $1 or so, enough to do two ICM's. It's what they put under he CPU's in computers to protect them.

[JohnGunn]

I would ensure that what ever you use is NON-FLAMMABLE, just incase you get a spark.

Also brakecleen can have bad effects on plastic parts as well as the insulation that is inside electrical components, if it's not bad now it very well could be after you spray it.

Why not just use air to cool it??

You have a good point here. I think that is why at the end of my message I suggested he could spray the outside of the distributor and get the needed information. The important purpose was to try and decide if heat at the CPS might be the cause of the problem. There are lots of ways to do that, and, if I had access to a source of pressurized air, it might have occurred to me to use that, at low pressure, because that would surely be less invasive to the system. I think your suggestion is a good one. Thanks.

Intermittent starting and stalling is a symptom of a dying ignition control module (ICM).

I agree with you that a failing ICM could easily show this symptom, but I assumed that when he referenced having tried a "new" "igniter" he was referring to his ICM. Only 1988 and 1989 Festivas have igniters, located inside the distributor, and I got the impression his is a later model with an ICM located outside the distributor near the coil.

I'll be interested in seeing how this turns out.

John Gunn
Coronado, CA

[FestYboy]

John, I'm surprised at you! You failed to ask if the coil is getting power.... can't have spark without a field to collapse.

i've used brake clean and carb clean to spray down the dizzy with no ill-affects.

[doylerl]

Have you replaced the fusible links on the ds strut tower yet?

[JohnGunn]

John, I'm surprised at you! You failed to ask if the coil is getting power.... can't have spark without a field to collapse.

Congratulations, FestYboy. It was just a test to see who would be the first to find my mistake. You've won a free, three pass, hand cleaning of all the windows of your Festiva the next time you drive through Coronado. I just bought a bottle of something called "Invisible Glass" which on first use seems to work amazingly well.

Of course, the next time his car refuses to start sasquatch should test to see that there is power at the + terminal of the primary of the coil.

John Gunn
Coronado, CA

[sasquatch]

good idea, thanks!

[jtugfestiva]

try checking the relay to the computer and see if its causing the problem. Try switching it with another identical relay and see if that works. Ive done that with a ford escort that was having intermittant starting problems.

[Biff]

check the ground termination right by the relays on the front LH fender.Check and clean fusible links.

[sasquatch]

after trying to fix it and not being able to find what was wrong, i left it... i was planning on bringing more spare parts of mine to see if anything would fix it, but some how it has fixed itself lol...