Habofro

So, this 944 is fun to deal with...

Lately, my car has been getting harder and harder to start, last year, the car would barely start when the temperature was lower than around 5c. Fast forward to this spring, car would start no problem 3/4 of the time. over time, it would get harder and harder to start, so I barely drove this car this year as a result since I didn't know what the issue was...

Now, it won't start unless it's 25c+ out. When it starts, there's usually one or two popping sound from the intake.

What should I check first? I was thinking either timing or ignition system. Am I wrong to think that it would be one of those?

Thanks for your help!

Jfrahm

DME temp sensor. http://www.clarks-garage.com/shop-ma...9.htm#dme-temp

jhowell371

What he said. Been there, replaced that.

Habofro

What exactly does that sensor do and how would it affect the start?

Also, I tested the ignition system a bit and my ignition coil secondary has 1 000 000ohm resistance? How is that even possible!

Edit: Mesured the resistance for the DME Temperature Sensor and it's mesuring 2.02k ohm right now and it's around 75F out right now. From what I've seen it's exactly where it should be!

jhowell371

It controls the cold starting fuel enrichment.

Dan Martinic

Test your AFM (see clark's garage). It also has a temp sensor that is critical for air/fuel ratios

Habofro

Makes sense.

As for the secondary ignition coil circuit resistance, do any of you know why it would be so high? I was thinking maybe rusty coils but that seems fairly unlikely... 1 000 000 ohm is waay above the specs so it's really odd to me that it would get that reading

I'll test out the AFM in a few minute and let you know the readings I got

Edit: I got 1.8k ohm from the AFM temp sensor, which looks about right considering it's around 85F outside

I'm getting no continuity now from of of the spark wires I;ve tested, worked last week so that's odd...

shortyboy

I would check speed/reference sensors too. Try jiggling the connectors if it doesnt start.

Habofro

Where are those located?

shortyboy

the connectors are near the rear of the engine by the oil fill and back side of intake manifold. These usually get corroded and jiggling them sometimes fixes the issue. Which would indicate the harness and or sensors need to be replaced