Guess the issue! (miss)

what is the miss

  • Spark - cap-rotor-wires-plugs

    Votes: 2 33.3%
  • Fuel - main filter

    Votes: 2 33.3%
  • Fuel - injector

    Votes: 0 0.0%
  • FI system electrical

    Votes: 0 0.0%
  • fouled plugs because of oil issues

    Votes: 1 16.7%
  • Head Gasket

    Votes: 0 0.0%
  • Vacuum leak

    Votes: 0 0.0%
  • compression issue - non head gasket (bad bad bad)

    Votes: 1 16.7%
  • Other

    Votes: 1 16.7%

  • Total voters
    6

autox19

True Classic
yup got a miss. I havent had a chance to really look into what it is, but thought this would be a fun way to use the poll. history. bought it early spring/late winter. PO said it was driven every summer since 2009. (actual owner passed away, this was form his son) plate tags were up to date. Started right up at his place even though the starter struggled. (click, click, little turn, click, ok I will turn over.) brought it to my mechanic friends house. drove it around the country block (1 mile each side) found it pulled to the left but ran like a champ. Replaced the caliper. filled it with gas (fresh container) drove it about 1/2 mile and it started to miss. miss got so bad I barely made it back. Corona hit. Just got back to it last night to load it up on the trailer and the miss was so bad it would hardly move forward, let alone go on the trailer. So here we go, here is a dark vid, it "rev limits" itself about 4k. with the throttle wide open.
1981 spider 2000 FI/ exhaust is just a glasspak dumping right out under the passenger door.
 

autox19

True Classic
Ok. So here is what i know. Not a vacuum leak as i sprayed carb clean all over and no change. Went to start pulling plugs to figure out what cylinder(s) are dead. I dont have spark plug pliars so i used my electrician pliars. As soon as a grabbed the boot i had spark between the boot and pliars as well as pliars to head. So plug wires are coming! Lets see if thats it

Odie
 

autox19

True Classic
The good. Wires replaced and started right up smooth. The bad after 30 seconds the miss is back. I stopped it. Started it back up. Again smooth. For a little. More like 10 seconds. Then miss. Same 5 to 10 seconds each time. So i pulled the vac line to the charcoal container and sprayed carb clean in. Nothing. Until i opened the thottle then smooth for a little bit. Back to fuel. I think the po had the same issue as with the car in the air, there is a new fuel filter on it

So next pulling plugs

Ugh
Odie
 

autox19

True Classic
I have not. But i will. The reasoning why i didnt was because it ran fine. I tried moving the dizzy by hand and it is solid. Also when i add carb clean to the manifold and open the throttle it smooths right out indicating possible fuel. I wish the intake didnt go over the top of the spark plugs making it hard to pull while running to see if it is a specific cylinder

Odie
 

autox19

True Classic
timing is correct, both static and dizzy. a guy on mira suggested coolant temp sensor. but although I have googled like crazy, i cant seem to find it. is it one of the 2 sensors on the top of the head?

Odie
 

kmead

Old enough to know better
It is a sensor on the coolant neck outlet. It should be on the underside of the T, often it is on top of the T. Two wires, typical Bosch connector.

I would doubt it is a contributor to this issue, it tends to be an all or nothing effect on the drive ability of a 124, they are very sensitive to this, the X much less so. That or the one used on an X is less damage and failure prone.
 

Jeff Stich

True Classic
You might pull off the distributor cap & check the 2 wires (green/brown?) for the electronic ignition pickup/sensor (the thick white cable that connects the distributor to the coil pack). These wires often get pinched (by the cap) or nicked/frayed (by the rotor) & can cause an intermittent short in the ignition, which can get worse as rpm's rise.
 
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