cold weather no start

[Skytrooper]

Summer is apparently over in this part of NY. Not only does it seem that we were robbed of a summer but, now my '83 944 N/A has decided that it doesn't like to start. I checked all the usual suspects
1. fuel flow at rail
2. spark (swapped coils with my 924S)
3. distributor and rotor (swapped from my extra motor)
4. changed out sensors (speed and reference)

No dice.

I am at wits end chasing this down. It had been running perfectly, then when the weather got cooler...POOF, it doesn't want to start anymore.

[Skytrooper]

Thanks George, I have Clarks Garage as a "favorite" on all my computers...including my computer at work

I was hoping that someone may have experienced an identical situation that would point me in the right direction. Is it the lazy way ? Yup, absolutely...but I kind of thought that was what this forum was about. Porsche guys helping other Porsche guys with less experience.

P.S. it did start this morning so I drove it to work. It started at lunchtime so now I just have to wait and see if it starts at quitting time.

[VinnyC]

Having the same problem. Would like to re-vive this thread to see if anyone can make some suggestions.

My 944 normally starts perfectly, but when the outside temp is very cold, it will not fire up...

[Paulyy]

petrol your using? higher octaine maybe?

did you make sure theres a spark at all 4 plugs?

[Pops944]

Long shot, but what's the status of your battery? If it isn't high on charge, and in good shape cold weather could put the output low enough not to start the car, but then when temperature creeps up a little it will suddenly work. In the winter I put my battery on an equalizer charge every couple of weeks just to keep it at it's peak for the freezing morning starts.

[zedsn]

Hi, Make sure your reference sensors are gapped correctly. The cold may take them farther from the reading points.

[962porsche]

what weight oil are you using ? the thicker the cold cranking weight the harder it is for a motor to turn over . do you know what the W on multi grade oils is for ? winter cold cranking weight . you should be using a 10W-30 in most winter conditions from about -10 to about 65 . if its bitter cold ( for days on end )then change to 5W-30 . these rules aply to full synthetic oils as well that is why they also have winter cranking weights . changing the octaine to a higher rating . a higher octaine gives a slower cooler burn . just like a lower rating gives a faster hotter burn .

[Cocacolakidd]

Check your battery for power and or warm it up - cold weather makes them low on power. Also check your connections - clean, clean, clean all points. If our 944's do not have plenty of cranking/starting power they will not start. Batterys hate cold weather also. When I was in upper Wisconsin I had a block warmer and a battery warmer plugged in when the car was off, otherwise it would not start when the weather was below 0* f.

[VinnyC]

I have an update:
I determined that when the outside temp is "Cold" I was getting no spark. I happen to have an old used reference sensor and replaced the sensor. Must be something about the cold outside temp that changes the sensors...

Good News is now I can get the car to start, but when she does,,, it runs terrible firing only 2-3 cyls...and dies.
So now I've determined its related to the sensor, but not sure if the used sensor I replaced it with is bad too, or the speed sensor is bad as well.
Off to get some brand new sensors...

Now some more questions:
If the bracket was not touched or adjusted, should the gap be affected? Could this cause the poor running condition I'm faced with now?

Could the speed sensor cause the poor running condition?

[zedsn]

Look around the past threads here on Pelican. You can get BMW sensors for about half the price of Porsche sensors and they are the same thing.

[Grandad#3]

Hi VinnyC, The BMW sensor is 12-14-1-708-619-M14 here on PP.

Cheers,
Larry

[TSNAPCRACKLEPOP]

small moisture filled crack in distributor cap. ? .

[VinnyC]

UPDATE:

So I replaced the Reference Sensor with a brand new sensor and now she fires up and runs great!
The cold temps must have some effect on the sensor...some have suggested "shrinkage" may have been the cause.

[JPSummers]

'84 NA....Sub Freezing Temps, Intermittent NO START.

Here's the diagnostics thus far:

NEW Reference Sensor after the last one tested out BAD....no resistance on the Ohmeter, Speed Sensor test 100% OK, that seemed to solve the issue of starting issues.

Fuel Pressure Good, Battery on Full Charge (though may be weak due to cold) tests at 12.6V cold, 13.8v engine running, Ignition tests good, DME seems OK. Mind you this was all tested and checked when it was warm (@ 50ºF), Sensors gapped correctly & YES there's tach bounce and Fuel Pressure at the Rail, even when it's <20ºF. Yes, the Grounds are good.

Once it's been run for a while (operating temp) it runs fine and everything's OK. In warmer weather there's NEVER any issue on starting or running, unless the starter over heats, then a quick manual spinning of the starter sets things right. But that's an entirely separate issue.

Today's Issue: When temps are below 25ºF the car starts labored, sounds like a TARDIS trying to launch then needs help w/ maintaining idle until it's warmed up. If it is allowed to stall then that's it. No amount of any thing will get it to fire up properly until the temps are higher. >20ºF. The idle will drop off to about 400 RPM then stalls, Then GAME OVER.

WTH is causing this?!?!? This is extremely frustrating

[Gawernator]

Coolant temperature sensor?

[Cocacolakidd]

Coolant temperature sensor - that's the second one on top of the engine ...and is always a problem if it is not functioning properly...goes to the DME for starting/idle settings plus switches when the engine is warm...

Also may be a rich/lean problem...more than likely a rich problem in the cold ... research the dip switches in the DME for possible solution ...

[JPSummers]

OK, Volt/Ohm meter comes out tomorrow when it's warm. We hit a high of 16º today.

It did have an amperage problem. In checking the Battery it was only charging up to 76% and no higher. It had a hard life, was 7 years old and needed replaced any way....Also New Terminals & Ground Cable as well.

Will post what I discover after I check the Temp Sensor. I checked Clark's Garage, got the #'s needed. Now it's supposed to be 25ºF while I'm testing this....I"m assuming I'll get a higher resistance than published since it's like 30º colder than the Testing Scenario.

Thanks for the input....YES, it is having a Rich problem. Thinking the fuel is crystalizing on the plugs....or so it seems....or it's flooded. In any case there's plenty of gas smell and none under the car.

[JPSummers]

oi, oi, oi.....after digging out from 6" of snow....kept the battery on a trickle charge last night, since I'd been cranking it.

Get in, crank, crank, crank, crank, crank, crank, RPM's increasing, then vroom.....runs perfect.

Geez, this fraulein is tempermental when she's frigid.

Seems to be if I run or drive the car every day, it starts fine the next day. But if it sits for more than 3 days when it's cold then it has issues.

Getting more very low temps the next several days, two of which I'm out of town. Continuing Trouble shooting when it gets warmer. Will post test results & culprits when I find them.

Thank you guys for the help. I'm sure I'll need it again later.