Stumble

[Pu241]

Spray with what liquid?

Water

But if they are bleeding voltage, letting it idle at night with the hood up will let you see the high voltage on the surface of the spark-plug wires. It will show as a blueish spiderweb of light. Might be more concentrated if it finds a ground close by.
Water misted on the wires might or might not help find this issue
My BP had a similar issue, turned out the wires had rubbed on the throttle cable and had wore small indention in the softer spark-plug wires themselves. Letting high voltage bleed/arc away. And not igniting the cylinder, creating a stumble. Got new wires and rerouted them, still need one more of those wire holders to keep them all from contacting each other.

[neanderpaul]

Shoot me now. I have now replaced with known good parts from a running festiva...
Plug wires, coil, distributor.
Stumble is still here. Anybody?

[gotrootdude]

"It will fall to 500 rpms and stay and sometimes it will go to 1200 and stay. It is also a little rough."
O2 sensor can cause a weird Idle. A hole or blockage in the exhaust system can cause it to act weird as well.

[getnpsi]

Only when the car is warm or all the time? I was just about to say o2 sensor issue too. Just yesterday my o2 sensor wires melted on my turbo manifold and i got the stumble after the car raN after a minute or so. I had to splice 4 wires in the rain. Good thing that is the last rain california should see until next year LOL.

You might have a hairline crack on the threads of the o2 sensor, or the sensor is bad. Try one of those off another car. O2's also rely on outside air too so if you have used a lot of chemicals that got on it, or a radiator leak will pee right on the sensor and ruin it too.

[91mcnasty]

My car has a similar stumble but Doesn't do it under a load just when idling.

[Christ]

Do these cars have egr? A lean condition can occur if the egr isn't working properly, which still cause idle or part throttle stumble. The fix is cleaning the egr valve and passages.

[neanderpaul]

No egr. Haven't tried the o2 sensor. Stumble is inconsistent but can happen when cold or hot.

[kellen302]

Me thinks O2 sensor if other stuff is not cause. My buddy's volvo does the same thing, and his dad messed up the O2 sensor when he was doing a rebuild.

[neanderpaul]

Didn't have time to put in a new 02 sensor before a BIG 2200 mile trip to Dallas. Put in a bottle of fuel injector cleaner and hit the highway. Seems to have taken care of my problem. This festy did sit for a good while. Put on a new denso O2 sensor for good measure when I was in Dallas.

[FestYboy]

Paul i still need to come down and help with the BP wireing correct? if so i can also help with the stumble if it showes up again.

[blkfordsedan]

Paul, I would take the TB off and clean it really good, along with the IAC passages. May not fix it your issues, but it certainly won't hurt it and all it will cost is the price of a new TB gasket. I was having similar issues and after thorough cleaning it idled smooth & steady as glass...just like new.

BTW, if you need a new Festy intake tube or air box let me know, I have some extras you can have.

[neanderpaul]

You know what? Skeeter's Keeper and Walth come over yesterday. Nate was running the show. Several hours in I got a call from the wife about puking kids and had to go home and help with that so I don't know how far they got. But knowing Nate it's probably ready to test. Will update. The stumble still hasn't returned.

[windy1]

could be fuel pump clog,or fuel line clog? or a weak fuel pump? or change distributer.
dirty injectors maybe? pull pump,or drain gas tank,refill fresh, blow out gas lines,get new fuel pump,fuel pressure regulator. air flo sensor? its either fuel system,or distributer. keep after it. mdoyleufo@gmail.com