runs fine, but rough idle and sometimes stalls

[thefenixgang7]

I have a 93 amigo that runs good at any rpm above 1000, but at idle its very rough and obviously misfiring on a cylinder. I have changed the plugs, and I will change the wires, cap, and rotor today. The choke is working correctly. It was idling fine till yesterday. No mechanical changes accept I removed the alt. And put it back on.
Thanks

[pig75]

I would say the fuel cut solenoid is not working. It's number 2 in the picture

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[thefenixgang7]

How do I test it?

[thefenixgang7]

Could it be the valve lash? It's not stalling anymore after I changed the fuel filter and wires. Still has a misfire at idle. It kind of sounds cammed at idle, but sounds normal after about 1000 rpms.

[pig75]

Could it be the valve lash? It's not stalling anymore after I changed the fuel filter and wires. Still has a misfire at idle. It kind of sounds cammed at idle, but sounds normal after about 1000 rpms.

It could. Valve clearance hot (inlet 0.008" exhaust 0.012")
Try pulling one spark lead of at a time to see witch cylinder is not firing @ idle
Could be a vacuum leak,burnt valves, worn cam, bad rings, dirt in the fuel system, etc

[thefenixgang7]

I pulled each plug and they all almost killed it. Valve clearance is within spec.
Here is a video
https://www.youtube.com/watch?v=fy4XuZC ... ata_player

[pig75]

Check ignition timing and idle mixture a correct would be a start.
Timing is 10deg @ 800rpm
Idle mix wind the screw in or out to get it running the smoothest
Do you have the workshop manual for the motor?

[thefenixgang7]

I do have a manual. It has a mixture control valve, so I'm not sure how to adjust the mixture. I will check the timing tomorrow.

[thefenixgang7]

I ended up having time to check the timing tonight and its advanced so far that the timing mark is about two inches before the timing marks. I imagine its about 20 deg advanced, but why does it run so well? Maybe its advanced because the vacuum advance stopped working? I retarded the dissy as much as I could and its still advanced, I will move it one tooth when I get a chance. Where should the vacuum advance hook to the carb if I wanted to bypass all the crappy relays?

[pig75]

With out seeing the carburetor i have no idea where the vacuum should go

[thefenixgang7]

Should there be vacuum to the advance unit at idle? Could the vacuum canister cause this problem? It may be silently leaking

[pig75]

There should not be vacuum at idle. When you set the timing disconnect the vacuum hose to the dizzy

[thefenixgang7]

I ran a compression test and I'm 130-140 on every cylinder. I also rebuild the carb, checked vacuum lines, set valve clearances, and I still have an idle miss. I have not reset the timing yet, but I don't think that's the problem. I know its been running rich for a while because the choke, but would that ruin the catalytic converter? And would that cause my problem?

[thefenixgang7]

Also I noticed that the distributor has slight play even when its tight. It's like it could move on its own. Not sure how to fix it. I'll look into it after work

[thefenixgang7]

Thanks for your help pig75. I found my problem. After replacing the plugs, wires, cap, rotor, fuel filter, and air filter, I decided to remove and clean the carb, and reset valve clearances. That however did not solve my rough idle. I decided to pull the distributor and found that the lower bolt on the mounting plate was loose, but that still did not fix my problem. At 8:30pm one evening I got to thinking about the carb design when I had it off and I read over this thread and your third post hit the nail on the head.

Check ignition timing and idle mixture a correct would be a start.
Timing is 10deg @ 800rpm
Idle mix wind the screw in or out to get it running the smoothest
Do you have the workshop manual for the motor?

Sure enough I overlooked the idle mixture screw on the base of the carb body. I turned it out about 3/4 turn and the idle picked up, so I reset the idle and it sounded great. However after that I noticed a slight lag while cruising. Today I decided to check the timing and it was retarded 3 degrees. I reset it to about 8 degrees advanced, and now its running like a champ. Just hope that my 16mpg gets better now that its actually firing before the piston is going back down. Thanks again.

[pig75]

Good to see you found the problem