down 2 cylinders?

[BadDog]

My car ran fine the last time I drove it (Saturday) but suddenly this morning started & ran like crap all the way to work. (At first I thought it was just because it was so humid out.) I don't have any real tools here to diagnose it with, but it felt like it wasn't firing on all cylinders. So, I checked the plugs to see if any were wet, and 2 and 4 were. I started her up, and with the engine running, popped off plug wire #2: no difference in idle. Put it back on. Popped off #4: no diference in idle. Removing 1,3,5, and 6 one at a time effected idle, so I'm guessing that 2 and 4 aren't firing for whatever reason.

I waited a few hours and tried starting her again, but she still runs like crap (and I have to go see a client across town... argh). The distib cap and plug wires look relatively new, but who knows if the points were changed at that time... I tried adjusting the spark wires around a little to check for a short, but to no avail.

I guess when I get home I can use my timing light to check for spark on wires 2 and 4, but til then I have to do 40 + miles of driving on 4 cylinders Is there a way I can check the points relatively quickly without screwing anything up? If they're bad, are they generic parts or specific to my distributor?

[BadDog]

OK, I just got adventurous and tried to check the points. My distrib cap has 2 spring clips, so I popped them up and took the cap off. I'm assuming the points are the metal contacts on the underside of the cap? They don't look carbonized at all. The rotor (?) contact looks good, too.

Could my plugs be fouled so badly that they're not firing (and haven't dried out after a few hours?) She's been starting hard lately, and I've had to pull back the choke lever 4 or 5 times total when trying to start her. I know this shoots gas into the carb each time, am I almost flooding it? I'm going to try to clean the plugs and check their gap...

[Dave Sommers]

Sorry bad dog, but pulling on the choke doesn't pump any gas into the engine. The design of the carbs has no accelerator pump, hench no gas is being pumped when you move the choke or the throttle. The choke moves the bridge assembly down away from the slidefloat and needle which enrichens the mixture. #2 and #4 feed off different carbs, so it is probably ignition related.

You are correct that the points are under the dist cap and if they look clean and unburned, then probably OK. But you should adjust and double check to be sure. As I recall, points pretty much same unless dual point distrirbutor. Replace them with a pertronix ignitor is the best long term solution anyway.

If you are only missing on two, then consider that you might have bad plug wires, or at least those two wires have the highest impedance. The condition of your coil and primary ignition circuit may be cauing a weak spark, and then two poor or bad wires may top it off for those two cylinders. Check the quality of the spark at the plugs of a couple of cylinders comparing to the bum ones. New set of wires fairly cheap item if needed. NGK makes nice set for the L24.

Good luck

[59ghia]

When you say plugs are "wet" what do you mean? are they oily wet or smell of gas? I would clean those plugs as best as possible. If they are black and sooty lookin they are fouled and probably are not providing much spark. Clean the plugs with emery cloth for now. Make sure to get between the electrodes. But it's been my experience, once they're fouled they re-foul real easily. If at all possible replace the plugs.

My guess is the points are ok since the other cylinders are not affected. Hope this helps.

[hmsports]

You might want to pop the valve cover off and see if the clips holding the #2 and #4 rocker arms has come undone and the rocker arms may be laying there. I've had this happen a few times because of either missing a shift and over revving or if your valve springs are old and soft.

Rick

[BadDog]

hmsports: that'd be a scary one for me!

Dave, I guess I was thinking about how gas pools in the bottom of the carb a little when the choke is fully engaged. I forgot it didn't really squirt any extra gas... and what do you mean by "Replace them with a pertronix ignitor"? what is that? Is that something to replace the points but keep the distibutor? Maybe I should take a pic of mine inside and out and someone can tell me if it's original or not...

Anyway, thank you all for your suggestions. I didn't have time to post what happened because I had to go to a client this afternoon. Anyway, I cleaned those 2 plugs the best I could, checked their gap, replaced them and set out on my way (if I had more time I would've swapped plug 2 with 1 to see if the problem moved). The car felt a little better, like only 1 cylinder was down.

I decided to stop by a Nissan dealer on the way to see if they carried new plugs that would work, since mine were were so fouled-looking. I was heading down the offramp when the engine felt like it stumbled a little bit, and suddenly she was firing on all cylinders again. I guess enough carbon must've given way

Anyway, I got 6 new NGK's from a parts store and I'll put them in ASAP.

Some of you might know from previous posts of mine that when I got this car, the timing was 10 degrees off, she was running really rich, and the carbs were so out of balance that the front one barely flowed any air... it's no wonder the plugs are so gunked up. *sigh* one thing at a time... I'm just glad that this is all it appears to be for now. Gotta invest in that AAA membership if I'm gonna drive this puppy more than once a week. My daily driver has roadside assistance as part of it's warranty

[Phacade]

I had a similiar problem once with my 240Z (before the rebuild). I could not figure it out and had alot of suggestions made as to what could be wrong and things to try (and I hope to God that you never try some of the half-assed things that were suggested to me). One of the better theories was I had a carbon build-up in my intake manifold. It was suggested I run some ATF through my then Webber carbs to clear it up. Not a good idea IMHO. Sure it COULD remove carbon but more than likely it will throw it all in your head and clog up the entire system. On a lighter note, it is quite interesting to see all the smoke this will produce from your tailpipe, I felt like I was at a Greatful Dead concert. And yes, my L24 was mostly shot before but this completly ruined it. Only thing left to do was give the original engine a decent burial.

Of course after all the above was said and done I found out my dist was toast, my coil was not much better and my wires were cracked and frayed in several spots. Probably the issue to begin with.

[BadDog]

Well I replaced all 6 plugs this morning, and she's still running fine. Still starting hard, though

Timberwolf: When I was 16 my buddy was "tuning up" my '74 Monte Carlo and slowly drizzled ATF in the carb while holding the throttle open to the tune of about 4500 RPM. He said it cleaned the carbon out of the motor. It *did* run a lot better afterward, but I remember the thick cloud of fog pouring out of the tailpipe, across 4 lanes of busy traffic

Anyway, I'll check the plugs again in a week or two to see how they're holding up. It'll be easier to adjust my mixture once I get my new-to-me air cleaners