Guess the issue! (miss)

what is the miss

  • Spark - cap-rotor-wires-plugs

    Votes: 2 28.6%
  • Fuel - main filter

    Votes: 2 28.6%
  • Fuel - injector

    Votes: 0 0.0%
  • FI system electrical

    Votes: 1 14.3%
  • fouled plugs because of oil issues

    Votes: 1 14.3%
  • Head Gasket

    Votes: 0 0.0%
  • Vacuum leak

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

    Votes: 1 14.3%
  • Other

    Votes: 1 14.3%

  • Total voters
    7

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.
 
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
 
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
 
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
 
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
 
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.
 
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.
 
ok, so like the dog who wont perform while being watched. the car proved me wrong. it didnt start smooth. well have 2 more vids



odie
 
This came in today. It should help
20200527_140143.jpg


Odie
 
A friend got an '81 FI spider that had been parked for a year or so, and as we got it running, it would have periods where it ran quite badly; we were working around the car trying to make it run better when I bumped the wire to the connector for the temp sensor on the water neck- and it solved the problem immediately! Motor smoothed out and revved freely. We cleaned the connector and sensor and the problem went away and hasn't been back. Yet.
 
A friend got an '81 FI spider that had been parked for a year or so, and as we got it running, it would have periods where it ran quite badly; we were working around the car trying to make it run better when I bumped the wire to the connector for the temp sensor on the water neck- and it solved the problem immediately! Motor smoothed out and revved freely. We cleaned the connector and sensor and the problem went away and hasn't been back. Yet.
hope I didnt jix ya by you telling the story! did it sound like the miss in the video?

Odie
 
similar sound when (attempted) rev, but his would start smoothly. It's an automatic, and it made a huge difference in drivability since they run more on torque; it was rather anemic before.
If it will run while you fiddle under the hood, you might be able to wiggle the connector and get an immediate change.
 
similar sound when (attempted) rev, but his would start smoothly. It's an automatic, and it made a huge difference in drivability since they run more on torque; it was rather anemic before.
If it will run while you fiddle under the hood, you might be able to wiggle the connector and get an immediate change.
will try for sure! it usualy doesnt die out for a few minutes so I tshould have no trouble getting out and wiggling it
I also have a new (correct) coil on its way, as was pointed out on Mira, it may not be the issue, but it isnt right and might cause an issue down the line that having franken part hard to diagnose.

Odie
 
On startup, my 86X was trying to die until it had run the temp up a bit. I wiggled the temp sensor connection and the problem went away. So, just posting my experience to reinforce the fact that the temp connection is a little bit@%. 🤬
 
If you take the temp sensor wire off and it doesn't change the way it runs, you have a problem there.
 
The latest. Checked the temp sender ohms through the pin at the ecu. Ohms showed correct for the temp. Had someone wiggle the wire and it stayed steady.
Took the plugs out to see the condition
20200528_162403.jpg

Cylinder 1 looked black where the others were brown. I put them back in and now the car wont start at all. Took one out to see if i even had spark. Yup. Looked a little weak but could be the ground wasnt good. Checked fuel before and after filter. Flow was great during crank and it wasnt odd colored or had setiment or rust.
So i will wait until the coil and ignition module comes in. Oh i did find 3 used ignition modules in the passenger side pocket. Like the po had the ignition issue.

Odie
 
The PO may have been chasing the wrong problem; his lack of success (multiple failures of the same component) makes it seem misdirected.
Are the modules that fragile?
 
The PO may have been chasing the wrong problem; his lack of success (multiple failures of the same component) makes it seem misdirected.
Are the modules that fragile?
I wouldnt think so. But wired up wrong maybe?

Odie
 
The pickup assemblies are rather fragile, most Spider owners carry a spare module, rotor and pickup assembly in the car. If replacing the GM module, don’t forget you need heat transfer paste as well (likely why the modules fail). The fact they are above the hot exhaust manifold and people are not thoughtful in their wire routing likely also effects their longevity as the twin cam engine does move around a lot on soft engine mounts, pulling on the connector coming from the distributor.

Brads book is a good reference. The fuel injection diagnostic manual we use on an X is also appropriate for the Spider.

Don’t forget other things like they ground cable to the engine/transmission.

There is a 124 Spider forum which varies in its efficacy, I used to spend time over there (I occasionally pop in) but I find the advice hit or miss with plenty of questionable information often proffered up.
 
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