81 Spider idles low on start up

[nibbes123]

1981 Spider idles low and rough on start up, when warm idles ok but not great goes up to 1200 rpm down to 900rpm. Tried to adjust idle but no change. Set up valve lash. new timing belt, plugs are new, cap, rotor and pick up new, new fuel filter, new ignition wires. I am lost any good advise would be great.
Thanks
Nick

[2ndwind]

Fuel injected I presume. Anybody near you with a well-running FI car? I like to switch out the Air Flow Meter (AFM) for a few minutes just to be sure that is not the problem. Also I've had a bad seat to my idle mixture screw. I forgot to mention the temperature sensor for the ECU at the coolant tee. If it is not reading correctly, your ECU might think the engine is already warm so it sends too lean a mixture to the injectors.

[4uall]

This might help with troubleshooting

http://www.fiatspider.com/f08/viewtopic.php?f=5&t=18519

We live in the same climate and I know my 1980 FI starts with zero issues and idles at 900. If I lived closer I would visit

There is always Andy's for help

http://www.andyspiders.com/

[narfire]

Plug the vacume hose from the brake booster and start the car and see if the idle smooths out. Vacume hose from the dist. disconnected? Sounds like you have an air leak somewhere. At least that is what I found when I had the same issue.

[nibbes123]

Ok will check for air leaks. The advise you gave me to check the auxiliary pulley to see if at 1:00 worked for it was at 12:00.
Thanks Chris.

[bradartigue]

I doubt it is an air leak; air leaks at cold temps on otherwise well running FI cars cause the idle to go up, not down.Worth checking, but not worth going too crazy over.

If you have a low idle when cold on an FI car it is because you aren't getting enough air or the car doesn't think it is cold. The air issue would be caused by a failure of the auxiliary air regulator, which is open when cold, and increases the idle speed by bypassing the throttle plate. The temperature issue would cause the ECU to not put the injectors full on when cold. The temp sender is in the T between the radiator hoses.

Start here, don't mess around with the cold start injector or thermo-time stuff because they don't do much in terms of progression from cold to hot, which is where your problem appears to be.

[nibbes123]

Checked the auxiliary air regulator and it is open a little when cold from sitting over night would this mean it is not working? Also cleaned it with carb cleaner and no change in opening. Are you supposed see right through the regulator when cold?

[bradartigue]

Checked the auxiliary air regulator and it is open a little when cold from sitting over night would this mean it is not working? Also cleaned it with carb cleaner and no change in opening. Are you supposed see right through the regulator when cold?

It ought to be fully open when cold. When plugged in there is a little resistor on there that heats up the strip and closes it. It never fully closes (well, some do but have a small hole in the metal strip, early ones just don't fully close) - sounds like that is what yours is doing. They aren't cheap (unfortunately, because they're a simple device) and you may be able to clean it by removing it, capping one side, filling it with electrical contact cleaner, shaking it up a bit, then dumping and letting it dry.

[nibbes123]

Thanks Bradartigue for the advise , replaced the air auxiliary valve and starts fine now and idles good.
Nick