hard start in cold weather

mcvic66 · Post by **mcvic66** » 14 Dec 2010, 12:53

on my 89 740 wagon non turbo i have been having problems starting it since it started getting cold out someone told me that there is a cold start valve and that most likely it was the problem replaced the cold start valve and it didn't make a difference and even started back firing so if any ideas let me know cause i dont know much about volvo's except there a good car.

lummert · Post by **lummert** » 14 Dec 2010, 13:24

I have had this same problem with my 1988 Volvo 760 Turbo Wagon for the past 5 winters. If the outside temp drops below about minus 2 degrees F the engine will not start. If I just wait until it warms up a bit it will start. I use 5W-40 engine oil so the engine cranks over fast it just won't fire. And at that temp it is too cold to be checking for fuel and spark.

mcvic66 · Post by **mcvic66** » 14 Dec 2010, 17:53

could the coolant temp sensor fix this problem cause i heard that could fix it to but i dont want to chase problems for the fact i dont have tons of money to throw at it but i dont want to get stranded with my kids with me

lummert · Post by **lummert** » 14 Dec 2010, 19:09

You just reminded me that I did replace the Engine Temp Sensor since last winter. I don't think an engine temp sensor costs that much new. I put in a good used one. This is not something that is really hard to replace unless you're all thumbs. The engine temp sensor is on the cylinder head under the intake manifold between number 3 and 4 cylinder. It's just tricky getting a socket in there to do the job.

Kmaniac in California USA · Post by **Kmaniac in California USA** » 15 Dec 2010, 06:26

Just to be clear, there are TWO engine coolant sensors, one to run the temperature gauge (obvious) and one to tell the engine computer that the engine is COLD (not so obvious). The second of these two sensors is the one to look at here. When working correctly, this sensor tells the engine computer when the coolant temperature is below 40 F (10 C). When the engine computer senses that the engine is below 40 F, it advances the ignition timing to compensate for the cold and start the engine more easily and keeps the timing advanced until the engine coolant warms above 40 F. This sensor is found under the intake, either between cylinders 2 & 3 or maybe 3 & 4.

I had to replace this sensor on my 740 a couple of years back. Not because of a cold no-start issue, but because it corroded and fell apart. It seems it doesn't get cold enough here in sunny California for this feature to function on my car.

Retired MVS Contributor · Post by **Retired MVS Contributor** » 15 Dec 2010, 07:36

The cold start temperature sensor does not adjust the ignition timing...It's function is to tell the cold start injector when to work, and when NOT to work...You don't want the cold start injector working when you are starting a hot engine, but you definitley need it when the temperature is very cold...The second sensor was used in early J and K jetronic systems...

If this car has the Regina system, and I believe it does, there is no second temperature sensor, this function is taken care of by the control unit...There are two other possible causes of this problem, one is the auxilliary relay and the other is the throttle swich...The auxilliary relay is on the right spring tower in front of the coolant tank...It's function is to isolate the system from the rest of the wiring and prevent external radio interference from killing the engine...

The throttle switch must be working correctly...If you listen very closly, (without the engine running) a click can be heard as soon as the throttle is opened...If you continue opening it, a second click will be heard when full open is reached...As the throttle is allowed to close from full open, another click will be heard, and as it reaches full closed, another click will be heard...If these clicks are not heard, the switch needs adjustment or replacement...

The OBD, located on the left spring tower brace, will tell a lot...Has it been consulted?...

Jerry

mcvic66 · Post by **mcvic66** » 15 Dec 2010, 21:04

well i did consult it and i had four codes one for the o2 sensor one for the cold start vave one for the knock sensor and one for battery voltage to high or to low

Post by **billofdurham** » 17 Dec 2010, 11:08

What were the codes?

Bill.

mcvic66 · Post by **mcvic66** » 23 Dec 2010, 15:01

the codes are 321,132,221,143

Post by **billofdurham** » 27 Dec 2010, 12:06

When you replaced the cold start valve did you erase the codes? Until they are erased the ECU will assume there is still a fault.

The battery voltage code could be dirty or corroded connectors at the battery. Make sure they are clean and tight, especially where the earth (ground) lead attaches to the body. Also check that the wires into the battery connectors are sound. They can disintegrate inside the connector and you won't see it.

Bill.