About 2 weeks ago my 88 744 n/a started running rough missing low idle black soot and rich fuel smell from exh pipe and feel a little when driving but no power loss i did a complete tune up about 3 months ago plugs wires cap and rotor fuel and air filter when this showed up i tested the coil primary read .93 ohms so i changed it to no help ive tried spraying either around looking for vaccume leaks no change but i pull fuel regulator vaccume line it idles a little better but still missing could it maybe the power stage and how do u test it thanks for the help

 

Check the water temperature sensor.

 

i doubt its the power stage, a dead power stage almost always means no spark at all which means no starting.... or intermittent no spark causing stalling when it warms up.

 

Is that the rad one or the block one

 

The block one in the rear under the manifold. It's basically the cold start choke and enriches the fuel mixture during cold starts.

 

Ok ty ill try that

 

test it, don't just randomly replace parts because they MIGHT be bad.
see the ECT stuff here, http://www.swedishbricks.net/700900F...Sensors,%20Etc

 

That show 89 and up is there one for before obd 1

 

pretty sure the resistance readings are the same for lh 2.2 and 2.4 even if the scale is a little different, a hot engine, should read like 200-300 ohms, while a room temperature engine should read 2000-3000 ohms, and a freezing cold engine should read maybe around 6000 ohms.

 

I was just reading later after the page that was sent and seen a different page and it basicly said what was happening on my car was the ect rough running black smoke plus i need to use a coupon at a store so the sensor will cost me 10 so ill get it today but how do u remove the clip holding the plug on it

 

i don't have a volvo anymore to double check, but many of those plugs, you press a square silver wire clip IN and then pull the plug straight out with a minimum of wiggling.

 

Well i replaced the coolant temp sensor idle is normal now but still black smoke and a slight miss so its getting better

 

Update drove to work this morning now no misses runs smooth but now acts like it either floods out or low spark till rpms get above 1500 then its fine untill rpms drop went to start at lunch now not doing it could be a heat related any help is appicrated