I think my 940 is running rich all the time. Now it is to the point where in cold weather, it almost won't idle. With the cold weather (upstate NY) it stutters, catches, idles rough, stalls when put in gear. It is a little better after it warms up (about 15 min). Runs like a top when you get it over 1500 rpm.

I'm thinking something with the IAC and/or ECT.

Any ideas on how to isolate this or other things to look at?

I've had this car for 12 years and it is really easy to work on.

Thanks.

 

the IAC wouldn't make it run rich, it might make the idle too high or low.

Regina is a little different than Bosch LH... it relies on a intake manifold pressure sensor and a air temperature sensor to determine the base mixture, then uses the o2 sensor to fine tune.

 

How's your Coolant Temp. Sensor?
First thing to look at in hard starts... The one under the third runner of the intake manifold.

 

My 1993 Volvo Regina system floods when cold. Replaced plugs OK for a day or two and then the same problem again. Started OK then began to flood and stalled out, won't restart.

 

Look for air leaks on the intake side. If it gets too much unmetered air, the computer will send extra fuel to match the air volume=running rich...

 

I checked the Coolant temp sensor a while ago and it measured OK, and I don't get any engine codes. The pressure regulator seems to work, doesn't leak anyway and holds vacuum. I noticed that one plug wasn't wet, I thought that maybe rotor, cap and wires might be the culprit. They are on order and will be here this morning. If that fails... I read that you can use a Bosch Regulator instead of the Regina one, I didn't see how I would fit that to the rail.. The battery is new and good and it cranks well.

 

I replaced the rotor, cap. plugs, wires and it ran great for a while. Then at -20C the flooding resumed. I had checked the Fuel Pressure Regulator, it doesn't leak anyway, I will measure the resistance at pins 5 and 13 to see if it's OK. I am using 5W 50 Synthetic oil and maybe that makes it too hard to crank?

 

i use 10W30 in mild to HOT weather on a swedish brick. I'd think 5w30 full synth would be the thickest stuff I'd want to use in a cold place.

 

SAE grade 5W should be just fine at -20°C. Grade 0W will crank a little easier but the difference will be almost imperceptible.