Just picked up a 94 850 non-turbo model to replace my daughters 940 that got totalled just before XMAS. It has only 107K miles and it appears to have been serviced by Volvo dealers as the plugs, air filter, battery are all fairly new and are volvo parts.
Anyway, the fuel mileage sucks big time so I figured that given the plugs, rotor, cap are new, that it is likely the O2 sensor. I replaced this today. While doing this, I noticed that there is a large hose from the rear (fuel tank) and 2 hoses from the throttle body that go nowhere. Apparently, the Evap canister was removed at some point. Since the 2 vacuume hoses were open from the throttle body, I just connected them together with a hose. Now I wonder if that was the right thing to do. I wonder if the better solution is to plug them until I can locate a used canister at a salvage yard. Comments please.

The other item I'd like is a decent vacuume hose diagram that can be read and has decent detail. The sticker on the hood is
useless. Got a pointer?

Also, I noticed that the cruise control pump under the battery tray had an open vacuume port. I cannot see what would connect here so I plugged this also. Should this have been left open? The is one hose from this that goes back to a bundle closer to the firewall where there are multple places to add hoses, but they are all factory capped. It is the other nipple that is open that I'm trying to sort out where a hose may connect to this. The speed control seems to work ok before I plugged this so now I'm wondering if I should have left it alone.

thanks for the help in advance

 

I will try to find a diagram.

Uncap the port on the cruise motor is stays open.

 

When you say the mileage sucks, what are you getting for mileage? We get 22-25 city and 27-29 highway in our 850 turbo

 

We get 31 mpg average for our 850 2.0 GLT, 50% city, 50% highway

 

I'd say 15'ish. around town if lucky. I did pull one plug and while the plug insulator was ok, the plug body (steel housing) was quite black with carbon. The exhaust is also quite black with carbon. When I pulled the O2 sensor to replace, it too had black carbon on it in places.
I think it was the stock O2 sensor. (Bosch LS 24) It appeared old, and had a steel cap with slits over the sensor. No codes set. First and only code is 111. the 94 940 (non-turbo) did not have an air pump while the 850 (non-turbo) does. At what temp does turn on? I assume one can hear it run if the key is turned on? If this were not working (again no codes) would this impact fuel mileage? I would think not but I've got a lot to learn with this vehicle.

I also have an ABS code set which points to the front right wheel. A quick check shows the wires at the wheel dangling in the breeze. What is the best place to get a replacement cable?

 

we get around 22mpg with half city and half highway. always run 92-93 octane
the secondary air system pumps air into the exaust to heat it up quicker when its cold. this really should not affect gas mileage thou.