Cold start problem

evox15 · 02-02-2005, 04:54 PM

So the last several days it has been fairly cold in the morning high 30s to low 40s (its florida) so to me it cold. I have an 86 944 N/A and it will not start at all if it is that cold outside, above 60 starts right up.. Today I replaced the blue temerature sensor and still nothing. The car just turns over and over with nothing happening not even a stutter. Whats strange is that today I pulled of some spark plug wires and the coil wire and looked to see if it would spark and I got nothing ( could be the culprit). My question is there anything else besides the temp sensor that might cause the ignition not to spark? I go to school full time and not having a car is very hard for me.

Thanks.

SoCal Driver · SoCal Driver's Garage

Reset the clearance for the sensors.

evox15 · 02-02-2005, 06:35 PM

How exactly would I go about doing this?

SoCal Driver · SoCal Driver's Garage

There are two socket head bolts that holds the sensor bracket to the back side of the bell housing. You have to loosen these. One is in a slot the other is a pivot.

The tip of the rear sensor has to be about the thickness of a dime off of the starter ring teeth.

Stuff a rag into the square hole where you check for the timing marks as you can drop the bolts into the clutch area real easily.

I usually take this bracket completely off with the sensors. I soak the hell out of the sensors with WD-40 or PB Blaster. I then remove the rear sensor and clean it and it's mounting hole so the sensor is an easy slip fit.

I put the bracket back in with the sensor out. I contact cement a dime to the tip of the sensor and slip it back into the hole. I adjust the bracket so I can just feel the dime on the sensor bottom out on the flywheel teeth. I snug the bracket so it's firm and pull the sensor out a little. I push the sensor back in till it bottoms out and check to see if there is a gap between the sensor and the bracket or if the sensor seated all the way.

You can also use some clay on the tip of the sensor to check the clearance.

I bet if you are able to pull the rear sensor out with out taking the bracket loose and use some clay to check the clearance it will be at least double the thickness of a dime. This is a typical cold start problem.

However you will find the sensors stuck tight in the bracket this is why you take the bracket out and soak it. Soaking it in the car can ruin the clutch.

evox15 · 02-02-2005, 09:59 PM

Thanks alot man. That definatly sounds like the problem since I am not getting voltage to the coil. So does the difference in the temperature cause the metal to contract so much that the sensor doesn't read the flywheel pickup? I had no idea that the cold had such a drastic effect on the materials.

SoCal Driver · SoCal Driver's Garage

Yes the cold can do that. The bell housing is aluminum and the sensor is a combination of aluminum, copper wire and iron ferrite (magnet). The clearance of about 1/32" is critical. Even more so in the single sensor S2's.

Don't forget to take the dime off of the sensor when you are finished.

Zero10 · 02-03-2005, 08:31 AM

My friend has a cold start problem, but only when it's -10C or lower. I bet it's the same thing. I thought it was harder to adjust the clearance than this. We'll definately look into it.

Thanks SoCal!

bearone2 · 02-03-2005, 09:24 AM

don't these cars have a coldstart/thermal timer that shoots extra fuel when starting cold.

my old bosch/fi volvo did, also could be the checkvalve out of the fuel pump not holding pressure.

evox15 · 02-03-2005, 12:17 PM

I tried to do this today and I centered the dime on the tip of the sensor but the dime seems to big. Are you sure that the hole size isn't too small for a dime? Mine is an '86.

SoCal Driver · SoCal Driver's Garage

I'll have to check. Maybe it was a Canadian dime.

Zero10 · 02-04-2005, 12:55 PM

I think a canadian dime is virtually identical to an american dime?....

SoCal Driver · SoCal Driver's Garage

Had to be smaller as the dollar is worth more in Canada.

Zero10 · 02-04-2005, 01:43 PM

Oh dear....
I'm not going to touch that one, lol.
I can't wait for your dollar to go back up, I bought a bunch of american money

G-Man55 · 02-05-2005, 02:02 AM

Hi guys,

My cold start problems which I thought were solved for good are back again (on and off).

Of course, when it starts I'm getting spark, but when it's not starting I'm not getting any spark.

Last time we found out that it was the wires going to the speed sensors that were the problem, they were loose and touching ground.
Once reconnected, it solved the problem for about 6-7 months. I hardly drove the car during that time period only a few times and short duration. But now the cold start problem is back, I'm almost convinced it's the clearance of the sensors this time.

BTW, the clearance should be 0.8mm according to:
http://www.clarks-garage.com/shop-manual/ign-02.htm

vital-transform · 02-06-2005, 10:49 PM

use a .8 mm washer, dime is too wide

SoCal Driver · SoCal Driver's Garage

Quote:

Originally posted by vital-transform
use a .8 mm washer, dime is too wide

But still the correct thichness.

ae1969 · 02-07-2005, 10:20 AM

Socals right......a dime will work fine....

WIth intermittent spark (assuming reference sensor is installed at right height) I am thinking your wiring could be giving you troubles. The boots on these harnesses are BRUTAL. YOu cut back the rubber and you will see corroded connections........

Here is what you will see with an oscilloscope...

Here is a pick of my old sensor with a washer glued on.....and the reference pin to the left of it...