QuestionI have a 1990 525 and it wont start in cold temperatures <10f. In cold weather it has trouble starting but yesterday it just wouldnt start at all. Im not sure if this has anything to do with it but i opened the ecu black plastic cover yesterday and lifted the ecu box out to find the ecu number. i dont think i pulled any wires. When I try to start it it turns over and if i floor it it will start for about 2 sec then die. I know I have good sparkplugs/ wires/ battery/ starter/ etc. I use 20w-50 oil since where i live in colorado it usually will only drop below 20 once or twice a year, however we have had very cold weather for about a month now (today's high was 8). Could this be the problem?
i inspected all the wires going into the ecu, and i dont see any damage so i have a hard time believing that lifting it 1 inch did anything. At what temperature might my fuel lines and injectors freeze up ( i hadnt used the car for two day). Do you have any sugestions for what to try? I checked the plugs and got a good spark.
Thx
Luke
AnswerLuke,
Well it's known that an internal combustion engine likes cold weather. When Air is colder it is more dense, and contains more oxygen for combustion. This is all based on an engine that is up to operating temperature. When the engine is cold, nothing fits quite right, as the engine is designed to run at 180°-210°F. As the engine warms, all the internals expand, and seal better. The pistons expand and fit tighter in the cylinders... etc..
There are only a few things that can go bad during cold weather, and that is the alternator, and starter. I just replaced the alternator on my '87 last week, as it stopped working.
I would check the voltage of the battery with a multi-meter, and it should be around 12 Volts. If the battery only has 10-11volts, then it is weak.
How long has it been since you changed the alternator? if it has been 1-2years, then it could be time to replace it.
If you are getting "good" spark, then you are not getting fuel. Listen by the back seat, and try to hear the fuel pump start when you turn the key to the "start" position. Your fuel pump could have died, and that could be why you are not getting fuel. Another way to check is to remove the fuel line from the fuel rail, and put it into a bottle and try to start the car. If fuel comes out, then you are in business. There are 2 lines, 1 has pressure, the other is a return line to the gas tank.
If you are getting spark, and fuel... yet the car still wont start, then it could be a timing issue, or a valve stuck open or something like this. I hope you understand it is very hard to diagnose a problem with out seeing the car, so I'm somewhat handicapped because of this.
If you have a battery that is weak, or just doesn't funtion well in cold weather, try taking it out and letting it warm up in your house over night. in the morning run out and hook it up quickly and try to start the car. If it starts, then it's just a weak battery.
Hope this helps,
Josh
P.S. Your oil is a good weight, but I think it's a little thick for where you live. I live in Georgia, and we rarely see temps below 30°F. I run Mobil-1 15w-50, and it's perfect here. I dont think this is a problem for you, but you just might not be seeing the full protection potential of the oil.
