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wil84911

Misfiring while cruising

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Started last night. Split second misfiring while cruising. This happened weeks ago and gas treatment eliminated it it seems. Could you point me where to start looking? I seem to be getting old for this default_laugh.png. Thanks
 
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12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

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How old is the distributor cap and rotor button?  Could be jumping fire.

Do you have the OE points distributor, if so the points may need adjusting or replacing.  Maybe just a good tune up would fix your problem.  Good luck. :)

Edited by siteunseen

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How old is the distributor cap and rotor button?  Could be jumping fire.
Do you have the OE points distributor, if so the points may need adjusting or replacing.  Maybe just a good tune up would fix your problem.  Good luck. 


Exactly my thoughts. Prob due for tuneup. Car came with Mallory. Thanks
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12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

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5 hours ago, wil84911 said:


Exactly my thoughts. Prob due for tuneup. Car came with Mallory. Thanks

Overall that doesn't look like the issue...

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13 hours ago, wil84911 said:

Started last night. Split second misfiring while cruising. This happened weeks ago and gas treatment eliminated it it seems. 

Some thoughts that popped in to my head while reading the thread.  Before I went to bed.  I'm glad your car's not red.

What do you mean by "cruising"?  And is the problem really gone now, after just pouring some stuff in the gas tank?

Edit - more correctly - did the problem really disappear weeks ago, and it has come back?

Edited by Zed Head

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Some thoughts that popped in to my head while reading the thread.  Before I went to bed.  I'm glad your car's not red.
What do you mean by "cruising"?  And is the problem really gone now, after just pouring some stuff in the gas tank?
Edit - more correctly - did the problem really disappear weeks ago, and it has come back?


Started hapenning at steady highway speed. Yes gas additive cured it weeks ago. Seems worse this time.


12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

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A tuneup can't hurt.  Sometimes minor issues become more noticeable at steady engine speeds.  Seems like a fuel issue would get worse after it started.  I know that in the old days we would adjust our plug wires to avoid crossfire caused missing.  Your distributor cap looks very clean on the inside, to Patcon's comment, but you can get shorts on the outside also, from dirt and grime.  New plugs, wires, cap and rotor might do it.  Good luck.

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  A little more info would help. Is the problem ongoing? I'd start with a complete tune-up. Did you fill your tank at the same gas station after the previous successful fuel treatment. They could have water in the bottom of their tanks. My Dad would never stop at a gas station that had a tanker sitting in the lot. He said filling the underground tanks would stir up the water sitting in the bottom of the tanks and allow it to be pumped into a vehicles tank.

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Thanks Mark. No seems problem is occassional misfire that got worse. But anyway its all coming back to me. Sanded the distributor cap and rotor points then drove it like a thief.. voila problem gone. Looking to complete the tuneup before the planned rebuild woohoo. Should I stay with this mallory setup?


12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

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Help please! This oldy cannot figure out which Mallory cap and points he needs. I don’t see any part number that matches ones on Mallory site. Thanks
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12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

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I used to run the Mallory Unilite but switched to the 123 Ignition setup.  A couple of comments about the Unilite / Mallory from my experience:

1. Mallory was acquired by MSD a while back and as a result the Unilite made for the L6 engine is NLA.

2. On my original Mallory setup the part number for the distributor cap was 270 and the rotor was 339.  You should be able to still get these through MSD or even Amazon.

3. The electronic module in the Unilite distributor was known for being susceptible to spikes on the 12V line and could go bad as a result.  Due to that I always carried a spare with me (never had to use it) and also installed a Mallory power line filter to eliminate any 12V spikes. 

Hope that helps and good luck with solving your problem.

Mike.

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Replacing the cap and rotor (or any other tune-up style work) with new certainly can't hurt, but I worry your sanding of the electrodes and having the problem go away is a red herring.

How do you know it was misfiring? What I consider a misfire is usually harder to detect at higher RPM's.  Did it cut out completely for a short period of time while you were on the highway? Or did it feel like it was just running unevenly and "pulsing"? "Judder-ing" (Is that even a word?)  :)

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Thanks Mike. Might look into 123. Captain, yes bursts of split second cutting outs. Light sanding to rid of dirt works. Anyway it is temporary. Thanks


12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

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Bursts of complete cutting out does sound like an electrical issue, but it sounds like something on the primary side of the coil and not something on the high voltage side. Of course, I reserve the right to be completely off base, but I'd concentrate your efforts on the primary side. Especially if there have been known issues with the Mallory module.

Good luck with the investigation. Is there an old-school points distributor you can throw in there to see what happens?

Another idea would be to carry a can of freeze spray and hit the module with a quick blast next time the problem occurs.

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Captain, thanks. So far today only one quick cutoff otherwise drove okay.

 

 

 

12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

 

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My pleasure. And if you find yourself down this way, get in touch and we'll see if we can pinpoint the exact problem together.

And... Don't get lulled into a sense of confidence about the problem that only occurred once in a certain day. These sort of things typically only get worse over time, and one day it's likely to cut out and not come back. And at that time you will be in the most inconvenient situation and location.

Better to have a handle on the problem on your schedule.   :)

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Here’s a video. Happened again today. Note: tach is inaccurate.

 

 

 

 

 

12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

 

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Yeah, I don't see a video either. Something went wrong there.

But your comment about the tach brings up an important piece of info...  The early version of the tach ran the ignition primary side through the tach, and because of this, if there are problems on the primary side of the ignition, it often affects the tach operation.

So the question is... What does your tach do when your engine cuts out? Does it drop to zero? (That question is probably answered by your video?)

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Sorry hopefully fixed.


12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

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Yeah, with the tach dropping off like that, it's probable there is something wrong on the primary side of the ignition system. And with the input from the other guys, it sounds like the ignition module is suspect.

 

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Best be ready - https://www.summitracing.com/parts/maa-605

And don't forget to check the ground circuit.  Often overlooked.  All of the coil's primary circuit current passes through the module, to ground.  A dirty/loose connection can cause extra heat, in a part that already runs hot.  Ignition modules hate heat.

You might just take the module out, clean up all of the connections and reinstall it.

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Thank you guys!


12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler

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Yeah, with the tach dropping off like that, it's probable there is something wrong on the primary side of the ignition system. And with the input from the other guys, it sounds like the ignition module is suspect.
 


Yes a new ignition module fixed the problem. Drove the car to a Z meet an hour away and it ran like a clock. Waiting for other parts to complete the tune up though. Thanks again to all.


12/70 2.6 block E88 heads Mallory DCOE40 3/2 Twice pipes Tokico 1, 3/4 in sways, ext oil cooler
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Sweet. I love it when a plan comes together!   :beer:

Keep your old one in your glove box just in case? I know it doesn't always work right, but it might get you home some night if the new one go wonky in a different direction?

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