308 idle issues

My 84 Euro 308 is having trouble holding idle after it is well warmed up. After driving for fifteen minutes or so, all is well. But after twenty or thirty minutes (or in traffic for a while) it loses the ability to hold idle, and I have to keep the rev's up. When I take it out of gear at a stop light or something, the rpm's surge below 500 and back up and you can hear the fuel pump relay clicking away and then the car dies. Aside from this, the car seems to run fine and has plenty of power.

Any ideas?

Actually- the car also has a cold-idle problem. It will not increase the idle speed automatically when cold. It's been doing this long before the warm idle issue. I've just been letting the car warm up for a while to avoid this. When cold, it idles about 900-1000 rpm (same as when warm). Unplugging the vac line from the warm-up regulator makes no change in the cold rpm's. Could these be related? I doubt it.

Thanks in advance for any help with this.

>>back up and you can hear the fuel pump relay clicking away and then the car dies.<<

I believe what you may be hearing clicking away is a relay on the relay panel. One will do this when the Fuel Distrib Plate falls to rest position, as part of the Fuel Pump Safety Circuit.

The surging itself sounds like a Fuel Mixture issue. If the Fuel Mixture is set incorrectly or Fallin Out of Adjustment it can/will cause idle surging/stalling problems. The first step in determining if this is your issue is to have the exhaust gas checked on an analyzer and reset to 1% if neccesary.

The cold start issue sounds like a bad Aux. Air Valve Problem or it's trigger switch the Thermo-Time Switch, located under the Intake Manifold in the block, by the Oil Filter Housing. Check the Thermo-Time Sw. first and replace if it's out of spec.

HTH's

Thanks JRV.
I will get the exhaust analyzed and report back.
Does the fuel mixture change for some reason when the car is beginning to run hot, like this one does?

I will have them looking for 1% of what? CO?

The clicking is coming from the dash panel as the car dies. So this is part of the fuel safety shut-off?

>>The clicking is coming from the dash panel as the car dies. So this is part of the fuel safety shut-off?<<

That's correct John. There is a safety switch in the FD to prevent flooding in case of stalling, that shuts the FP off.

Yes 1% CO "before the Cats" if any.

Yes the CO/Mixture can change as the engine warms up and the way an engine acts to 1% for example is different when an engine is cold or hot, and weather can effect the way an engine runs to a specific mixture.

Sounds like a few minor adjustments might solve your problems.

HTH's

This Euro car has only two cats and no muffler. Weird, huh? How can we check the exhaust gases before the cats? Is there access somewhere?

I assume I should have someone who knows these fuel systems inside and out make these "minor adjustments"? There is no good ferrari mechanic in the area, but I'm sure there would be someone who knows the Bosch system since it is used on many other cars? It sounds out of my league since I don't have an exhaust analyzer to check the adjustments.

Thanks again for all the help and taking the time to run this forum. It really helps people like myself who want to learn about these cars.

John,

Yes it's a standard Bosch system and most Porsche or MB mechaincs familiar with older cars will know the system (MB mechaincs especially).

Hopefully there is a Test Port on the exhaust before the cats somewhere. It's not really. possible to set accurately once the Cats have changed the numbers is why for true Checking/Setting pre=cat numbers are so important.

If your local guy needs help that's not a problem. Although the checks and adjusts are very simple and easy.

Regards, JRV