Rough cold start - What if it is not the Auxiliary Air Valve?

Check all electrical ignition components. They are also affected by tempreature and contraction/expansion.

 

Not sure that that AAV is actually the correct one for your car, but it's doing the generally right thing so it's not causing this issue (and is probably OKish).

What version 1986 Mondial 3.2? Euro, CH, US?

What is the color of the fuel distributor? Silver or black?

Can you post a photo showing more of the whole engine bay?

 

Certainly wouldn't hurt to confirm that the AAV internal heater is correctly getting +12V whenever the engine is running. However, I believe that symptom would be more "idle is high at cold start-up and takes a long, long time to come down" (as the AAV should still eventually close just by absorbing heat from the coolant expansion tank). The silver fuel distributor (a K-Jet without Lambda system) removes a lot of other things that might have caused a symptom like you reported. IMO, the first suspect to investigate in your case would be the WUR behavior -- confirm the cold control pressure and the warm control pressure are in spec as having the right relationship for cold vs warm is essential for cold-running to work properly (almost unfortunately, since the mixture gets tweaked up in the warm condition, the warm control pressure can be bonkers yet the car run fairly well when warm, but cold-running won't be good if the cold vs warm relationship is bonkers). Good Hunting!

 

Could it be the frequency valve relay? Mine fell out of its base and the car ran very rough when cold but was almost OK when warmed up. The relay is behind the carpet on the right side of the trunk (looking forward). The frequency valve itself should buzz when the car is running. It is on the fuel distributor--or does this car not have one since it's Euro...

 

Euro = K-Jet without Lambda = no Protection Relay and no Frequency Valve.

 

Does it run/idle ok after it warms up?

 

Some common "rough running" issues:

Clogged filter screens in WUR
Clogged filter screens in fuel injectors
Plug wire resistance increased
Arcing wire extenders
Spark plugs fouled

 

No! Make the measurements before buying/fixing an expensivecomponent (or have a Shop make the measurements -- Shops that work on classic Volvo, MB, or Porsche should be able to do it). The problem might be something else...

 

Good to know the car runs well when warmed up.

Maybe the engine coolant tempertaure sensor is corroded or covered in deposits. It is among the things that direct the fuel ecu computer in start up and warm up enrichment. You can check the resistance with an ohm meter, it should read about 2500 ohms at room temp, and 340 ohms at 80 C. It is under the intake plennum on the left-ish side, might need to remove the oil filter to get in there to unconnect the harness. You can remove it to test or replace with a ratchet and extension.

(The orange in the pic is the oil filter, the brass sensor is peeking out just behind the throttle cable tube.)

 

It's a 1986 euro Mondial 3.2 (K-Jet without Lambda) -- no injection ECU and no coolant temperature sensor(s) nor coolant thermoswitch related to the injection system's operation.

 

The WUR is pretty bulletproof. Excepting the filter screens which can get clogged with old fuel varnish. This is a problem throughout the K-Jet system. Fresh fuel is a must. Cleaning the screens will require disassembly. You'll understand why after you've done it. Adjusting the WUR is a bit of a lost art. And it is key to the system. It should be called FMR - Fuel Mixture Regulator.

Rough running often has multiple causes.

 

Ah yes, for some reason I thought it a 1988.

 

Paging schelle_pelle

Is there an end to this story? Did you resolve the cold start issue? Did you have to dismantle the warm up regulator? Inquiring minds (like mine) want to know

Bye

 

Mine was doing the same thing, I replaced the cold start relay and fuse all all was well, never any more problems. I f I have said this before, excuse me, but I ALWAYS start diagnosis with the fuse/relay board. Seems like 90% of the time, with anything electrically connected, that is where the problem is. I do fuse box "maintenance" every five years now and I always find a bunrt connector, replace ALL the fuses and relays with new, clean the board, fix bunt connections, spray liberally with Deoxit (Great stuff!) Everything works better, faster, brighter!
Alden