Car suddenly running rough and stalling

[dbrick]

I defer to Tom on testing, he has all my stuff!! , and yes, we all use the same basic set up. BTW, did you notice if the tachometer start waving around just BEFORE it runs badly? Car I was discussing above did that, tack flopped up and down for a few seconds, then the stalling and missing started. If it happens again and you know somebody with an oscilloscope, it may point you in a direction. Lets hope for the cap.

It's odd, a properly running engine and a properly beating human heart have a very similar waveform on a scope.

[Skyman]

I defer to Tom on testing, he has all my stuff!! , and yes, we all use the same basic set up. BTW, did you notice if the tachometer start waving around just BEFORE it runs badly? Car I was discussing above did that, tack flopped up and down for a few seconds, then the stalling and missing started. If it happens again and you know somebody with an oscilloscope, it may point you in a direction. Lets hope for the cap.

It's odd, a properly running engine and a properly beating human heart have a very similar waveform on a scope.

Yes, tach swing, just as it starts to go bad. Since I replaced the cap and rotor, things are good so far. I just don't think it will be that simple though.

[tjp]

Although my issues were different, a new cap and rotor solved one of my rough running issues so it actually can be that simple. My other issue was a slightly broken wire coming off the coil that was totally un-noticable to the naked eye last summer on the way back from Mid-Ohio. It wasn't until the break was almost all the way through that we could actually see it.

Tim

[spl310]

I suspect a loose wire somewhere. I would judiciously check all connections.

[Linda]

I had a bad connector on a MSD wire recently, it broke. So check all that too.

Linda

[Skyman]

I suspect a loose wire somewhere. I would judiciously check all connections.

I had a bad connector on a MSD wire recently, it broke. So check all that too.

Linda

I have checked the resistance of every wire from the coil to the distributor. If it were prior to that, the tach would just drop along with the power. If, per se, it were coming from a bad connection on the ignition switch or something then it would all just fail. It is the wild tach swings associated with the misfiring that tells me it is between the coil and distributor. I'll be more prepared to test if it occurs again. I really appreciate all the ideas.

Although my issues were different, a new cap and rotor solved one of my rough running issues so it actually can be that simple. My other issue was a slightly broken wire coming off the coil that was totally un-noticable to the naked eye last summer on the way back from Mid-Ohio. It wasn't until the break was almost all the way through that we could actually see it.

Tim

I was kind of saying that in hopeful jest. I really do hope it is that simple. Thanks for your support.

[Skyman]

Over 200 miles now, and no issues. Maybe it was just the cap & rotor?

[notoptoy]

I have seen a crack in the cap cause all sorts of weird running issues, especially if there is high humidity - it'll "rain" inside the cap.
My typical test for that is to simply watch the car run at night, as dark as you can get it, to see the arcing.

[dbrick]

Over 200 miles now, and no issues. Maybe it was just the cap & rotor?

I agree, bad cap will make you crazy. BTW, did you see the cool wheels in SLC in the forum classifieds? http://www.311s.org/phpBB3/viewtopic.php?f=6&t=14467

[GarageGuy]

I put a new coil on mine. Same symptoms. The old ones get hot and stop working

[redroadster]

How many miles now 12 yrs later ?