Trouble starting, idle issues, surging under 3k rpm

[MNT250]

I started having these issues about 3 weeks ago, prior to this I had no issues with the car and it would fire up very quickly. Nothing had really been changed or messed with. The day I think it started the battery was low however the car started idled for a moment then died, so I cranked it, it almost started, stumbled a few times and the battery gave out after more cranking. Later I jumped it and after a lot of cranking and stumbling it finally fired up and stayed running.

Now since then it has been difficult to get the car started and usually almost starts a couple times then stumbles before starting to run at which point I have to give it a good bit of gas or it'll die and even in doing that it seems to lag behind my foot on the pedal and not rev right away. Once i'm driving I get a consistent surging under 2500-2700 rpm until I hit around 3000+ and it's smooth without issue at that point. (ie even if I smash the pedal it'll start to go & buck off and on until I pass that RPM mark) Starting from a stop I have to be sure to give it more gas or this causes real issues with taking off. Idling at a stop is a little scary as it has died but so far has started right back up if that happens. Idling with the A/C on always seems to cause it to eventually die.

Anybody have some ideas of what these set of issues might be? I've read a lot of posts with lots of different suggestions so i'm confused as to what to try. A tune up is on the list but i'm waiting on my distributor cap & rotor to arrive although this issue may be something unrelated to the ignition. I'll be replacing the plugs, wires, coil, cap and rotor when those arrive but I don't want to overlook another issue I could have dealt with at the same time I do the tune up.

[David T]

"Nothing has really been changed or messed with". Well it has gotten colder. My first guess would be the CPR aka warm-up regulator.

[MNT250]

"Nothing has really been changed or messed with". Well it has gotten colder. My first guess would be the CPR aka warm-up regulator.

Well not really here in the pacific northwest, the other day was back up above 70 but i'll for sure look into that. That would be in line with the other issues once the car is running and driving?

[Bitsyncmaster]

Your description of the sudden problem sounds like something electrical. Does your FV still buzz. Can you check the mixture (dwell)?

[MNT250]

FV is still buzzing away. Unplugged it while running and it got really rough, just about died. I don't have gauges to check the dwell unfortunately.

[David T]

FV is still buzzing away. Unplugged it while running and it got really rough, just about died. I don't have gauges to check the dwell unfortunately.

How does it run once it is warmed up? If it runs well warm-hot the problem is most likely the CPR. If it runs badly hot I would suspect the secondary ignition system, spark plugs, ignition wires, cap and rotor. If this happened suddenly it is also possible you got some bad gas with some water in it. Use up the tank and fill with fresh and see if the problem goes away. You can also look inside and see if you see a bubble of water floating around on the bottom of the tank.

[MNT250]

How does it run once it is warmed up? If it runs well warm-hot the problem is most likely the CPR. If it runs badly hot I would suspect the secondary ignition system, spark plugs, ignition wires, cap and rotor. If this happened suddenly it is also possible you got some bad gas with some water in it. Use up the tank and fill with fresh and see if the problem goes away. You can also look inside and see if you see a bubble of water floating around on the bottom of the tank.

No change in the way it runs hot vs cold overall still get the surging under 3k while driving, dying with A/C on at idle ect.. Previous owner mentioned it could use a tune up when I purchased it but it always ran well and fired right up until these issues. It has been over 4 years though since the last one according to the paperwork, at the same time the stage 2 and a bunch of other things were done. Only 6,000 miles since then though. As soon as those parts arrive i'll be replacing all of that and hopefully it helps. I also got some Lucas gas additive stuff and filled it up with new gas but hasn't made a difference yet but i've only driven maybe 25 miles since

Thanks,

Micah

[Jonathan]

Go get your battery tested. That's the only thing you mentioned that early on had problems. I wouldn't go any further until you confirm your battery is ok.

[David T]

No change in the way it runs hot vs cold overall still get the surging under 3k while driving, dying with A/C on at idle ect.. Previous owner mentioned it could use a tune up when I purchased it but it always ran well and fired right up until these issues. It has been over 4 years though since the last one according to the paperwork, at the same time the stage 2 and a bunch of other things were done. Only 6,000 miles since then though. As soon as those parts arrive i'll be replacing all of that and hopefully it helps. I also got some Lucas gas additive stuff and filled it up with new gas but hasn't made a difference yet but i've only driven maybe 25 miles since

Thanks,

Micah

If it's running crappy when hot AND cold it isn't the CPR. I would start looking at the secondary ignition. Try running the motor in the dark and looking for sparks or blue around the wires or distributor. It *could* be a bad coil. Pull and read the spark plugs. See if they are all burning clean.

[MNT250]

If it's running crappy when hot AND cold it isn't the CPR. I would start looking at the secondary ignition. Try running the motor in the dark and looking for sparks or blue around the wires or distributor. It *could* be a bad coil. Pull and read the spark plugs. See if they are all burning clean.

The coil wire was arcing by the boot on the distributor cap, swapped it out and its running perfectly again. What a relief. Guess I should have just waited to see how the tune up went, but it seemed sudden and I assumed it was another issue. Anyhow, thanks for the help and suggestions!