Smoke

What type of smoke? ie. White, blue, black, smells of oil , sweet smelling (coolant), fuel smell, etc.?

 

Do a compression test. Squirt a little oil into each cylinder through the spark plug hole and test again. If the compression readings go up with the oil added, you have worn rings/cylinders. This can cause smoke in the exhaust.

 

Compression test is always good. As mentioned it can be only 3 types of smoke. Depending the color you should take different actions.
1. coolant = white and smells usually sweet
2. oil = blue
3. fuel = greyish

obviously you can have a mix of each.

 

Since you had the heads off for service, I will make a wild guess that its the head gasket not sealing, and you are getting some sort of coolant blow by into the exhaust. If the car was not smoking prior to the head service, it is probably not a piston/ring problem. Might make sure the head is torqued down correctly, the procedure for torqueing is in the workshop manual.

 

Is there a breather from the rocker boxes to a connection on the inlet manifolds with a valve in the line, a few years since my mondial. If it is obstructed it will not be drawing off the crankcase pressure. I cannot recall the setup but worth a look

 

Sounds like ignition problems, not fuel delivery.

 

I take it, this has the bosch k tronic injection system. ? I have seen something similar where the balance of the fuel delivered to each cylinder was wrong, the engine was misfiring and making smoke- also the oil level in the sump increased, this being due to excess fuel to some cylinders that was washing past the piston rings into the sump.
The fix was to get an overhaul kit for the injection system distributor head( the casing on the right rear in the engine bay with all the small injection lines atteched to it) turned out this has a diphragm inside that had split, so the fuel supply to each unit was wrong, some cylinders were getting max fuel. The kits can be found on e bay, look on the side of the casing for a bosch number and google it

 

There is still interest in which color smoke and what it smells like but too much fuel is not good and is a possible cause for smoke. Can you make a video of te smoke?

If they are still the first injectors you might want to swap them for new as they wear out at some point. Cleaning these old injectors does not make sense if I may say so.

 

I think it was a bosch unit the 22r used when they added first added the turbo to that engine, circa 86. I had issue with the cold start injector which made it smoke and sputter, spit excess condensation and fuel out, then it got really bad quickly when extreme cold came on. The fuel dilution of oil is not good so do check that and attend to it quickly if it is.

 

Have you tried putting injector cleaner in the fuel yet, it might be worth a try. My mondial used to have the engine cut out when slowing down for a junction, ie coming off the throttle and braking.
I was not getting any other indication like smoke etc, but a treatment of injector cleaner yearly sorted it out.
Re changing injectors, mine had the same injectors from the factor in 1987 to 2013 when i sold it, it was still going great guns.

 

I think that it is an excellent suggestion. You can disable the cold start injector by unplugging it on the air house (blue connecter) then at least you know that it is getting fewer fuel when starting cold. Keep in mind that this system supposed to work with this injector so eventually you need to find the root cause.

 

There you go! I guess it is just part of the solution though. Ps. It common practice to replace all injectors and they are not so expensive. Old ones have a habit to fail much quicker then new ones even when they are cleaned in a sonic bath.

For the fuel distributor you will need to have a micrometer. keep in mind you cannot just rebuild it although it seems only rubber O-rings and metal plates. I do think it is a good idea as it is just old rubber inside. Recently I helped out to rebuild a Porsche 924 where the injectors kept on providing the maximum fuel flow even when the flow plate was in it's default position (stationary). all 4 rubber O-rings deteriorated. Have a look on youtube. If they do not work with a micrometer then dismiss such videos.

 

Put a search in google for the bosch k tronic fuel injection system, it will explain how it works

 

The uk volvo owners site has a good write up, lots of others as well. You need to understand how it works before you start messing with it

 

The "mixture adjustment screw", which is located in the middle of the "mixture control unit", and is adjusted with a 3 mm hex head, is for idle mixture. Running mixture is set by the pressure difference between "system pressure", and "control pressure". System pressure is adjusted by adding/removing shims from the "control pressure regulator". Cold control pressure is adjusted by moving the support pin in the "warm up regulator". Warm control pressure is adjusted by moving the "fuel cell" in the warm up regulator. Correct pressure values are in the service manual.

 

This video shows adjustment of the cold control pressure. The tech starts with the pin flush with the housing. The warm control pressure adjustment is not shown, but should be done first. Also with the pin flush with the top of the housing. Then adjust cold control pressure. Ball park numbers for pressures are 5 bar - system pressure. 3.5 bar - warm control pressure. 1.5 bar - cold control pressure.

 

This video shows proper setup, and adjustment of the system pressure regulator with shims. However I DO NOT recommend drilling a hole in the warm up regulator. Adjust the warm up regulator by moving the pin as in the previous video posted.