Rough running at startup

genolan · #1 (**permalink**) 07-07-2014, 04:50 AM

The car starts up and runs rough for about a min or two then she's fine. It only happens after the car is sitting overnight and is cold. It sounds like it's missing on one cylinder on the passenger side and I can see a little darker exhaust on that side. What could it be and why would it clear up and run great after that.

6t8stang · #2 (**permalink**) 07-07-2014, 05:33 AM

What do your plugs look like? What are the temps of the individual exhaust ports at the headers, especially on the passenger side?

genolan · #3 (**permalink**) 07-07-2014, 07:00 AM

Plugs are coming out tonight, I was looking at temp guns and was wondering what the max temp of the gun needs to be to read the headers. I saw a few that went up to 1022 deg F for $29 on amazon.

jhv48 · #4 (**permalink**) 07-07-2014, 08:27 AM

Choke sticking?

Tommy · #5 (**permalink**) 07-07-2014, 08:50 AM

We need a lot more info. Carburetor(s) or fuel injection? Choke (manual, electric or heat controlled)? Anything seem to make it better or worse (e.g., pumping the gas pedal)? Have you fouled out plugs before?

genolan · #6 (**permalink**) 07-07-2014, 10:00 AM

Quote:

Originally Posted by Tommy

We need a lot more info. Carburetor(s) or fuel injection? Choke (manual, electric or heat controlled)? Anything seem to make it better or worse (e.g., pumping the gas pedal)? Have you fouled out plugs before?

More info
1) Carb with electric choke
2) I need to pump gas to keep it running.
3) higher RPM around 2k cleans it up in a min or two
4) Once it clears it runs strong and never misses again until fresh start after overnight rest.
5) The exhaust seems to look richer on the passenger side which leads me away from a choke issue. I'm leaning towards bad Plug or wire.

DesertMK4 · #7 (**permalink**) 07-07-2014, 10:26 AM

We are all just guessing here...but with a Holley you have a fast idle adjustment that could be off. Fast idle (when choke is on) should be around 1400-1600RPM. You might try cleaning and then resetting idle screws. See Holley TV. Some Ford engines need the spark plug wires separated (mostly between the 7 and 8 plugs). Reading the plugs should at least tell which plug isn't firing. Good luck tracking down a temperature variable problem.

jhv48 · #8 (**permalink**) 07-07-2014, 12:18 PM

Sounds like the choke isn't staying closed long enough to give a cold engine the richer mixture it needs.

genolan · #9 (**permalink**) 07-07-2014, 03:42 PM

I turned the ignition and and watched the choke open about a 1/4 of an inch which took about 1 min then started it up. The roughness was 90% gone so I just need to adjust the choke so it appears. It must of been running way to rich.

Tommy · #10 (**permalink**) 07-07-2014, 03:48 PM

Gary,
I wrote this before your last post. Take it for what its worth.

This is information, not a diagnosis. ... I run my 410 Windsor with carburetor (no choke) and fairly cool plugs. I have to pump it a lot on cold starts to keep it running until it warms up a bit. When the plugs get several thousand miles on them, I start noticing a miss at lower RPM until it gets good and hot. When the miss persists long enough to be annoying, I change the plugs and everything is OK for a while.

My advice is to remove the air cleaner, manually adjust the idle screw a little higher (so you have time to get out of the car and observe the carburetor without the engine dying), and see what the choke plate is doing. Don't get too close (backfires are bad). My guess is that the choke is not closing enough and that is why pumping the gas helps. If the choke is working ok, I'd suspect the plugs.