Early '83 944 poor running issues

Gary2397 · 04-02-2009, 12:11 PM

This old 944 of mine has poor running condition in cold weather
after park outside for 8 hours. The temperature takes long time
reaching its normal level.

During good sunny day or outside temperature is cool, it runs fairly
well.

Does anyone has any solution to what sensors, components, etc.
causing this?

_________________
'83 944 Driven daily

John_AZ · 04-02-2009, 12:40 PM

Gary,
You could move to Southern California and get out of the bad weather or get a similar lifestyle here in Northern Arizona

.

I would go for the obvious stuff and change the thermostat and maybe the engine temp sensor. The engine temp sensor sends a signal to the DME.

This is what Clarks says:

Engine Idles Rough When Cold.

Possible Causes Checks Procedure
DME Temperature Sensor On startup when the engine is cold, the DME temperature sensor tells the DME computer that the engine (coolant) is cold. This causes the DME computer to supply a much richer mixture to the engine (a hot engine atomizes fuel better). When the DME temperature starts to fail, it normally sends a higher than normal temperature signal to the DME computer. The DME computer in turn supplies a leaner mixture to the engine than that which is normally required. So, the engine runs rough (lean) and if it gets bad enough, may not run at all.
Check the cold resistance of the DME temperature sensor
OR
Vacuum Leak Inspect all hoses connecting to the intake manifold which are downstream of the AFM. N/A END

Me again.
I would also check the underside of the intake "J" boot for loose clamps and cracks.
Check for cracks by the auxillary air valve (early) or idle control valve-ICV or ISV hoses and maybe clean out the valve. Really a pain to get at without taking off the intake.

GL
John_AZ
1988 924S + 1987 924S

SolReaver · 04-02-2009, 08:02 PM

What John said.
Plus...check the grounds, alternator connections and have the battery tested. Vac leaks from inaccessible areas can be checked for by using spray carb cleaner (be careful)

Gary2397 · 04-03-2009, 10:59 AM

Well, I was living in San Jose, CA for a long time before moving
up here for some reasons. This 944 was CA car. Here in OR, it
rains too much. There is not much weather break here.

I think I replaced the thermostat and fan switch with lower temperature
type. All the auxillary air valve and other 3/8 hoses under the intake
manifold are new.

This battery was drain out sometime a year ago due to I forgot to
unplug the heater fan in the cigarette lighter. I installed a rebuilt
alternator a week ago.

The battery now tested at 12.35V with multimeter while the car
is not running. When the I start the car, it read 13.88V-13.90V.
I am looking to replace the suspect such as battery and coolant
temp sensor.

SolReaver · 01:55 PM

OK, rebuilt Alternator, check the connections and grounds anyway. It never hurts. The battery should be tested at an auto parts store. It may give good voltage but be low on amperage. A load test would confirm or deny it as a culprit. While you are there they can check your alternator output just to be sure that low juice is not your problem.

Check the temp sensor to see if it is getting power and what it is sending back to the computer. The temp sensor is a logical culprit. They don't last forever and it is not that difficult to replace. Is the car running rich by the smell of the exhaust?

Is it moisture or temperature related? Moisture can also cause some probs with plug wires, coil, distributor (cap), etc. Clean and inspect them spraying a little wire dry or silicone on them and a pinch of bulb grease on the connectors. Check the plugs to see if they are the correct heat range and that the gap is correct. People in Portland don't tan, they rust. With such excessive moisture conditions you might want to have all the shields on your engine if they were removed in sunny CA and you would not be out of line sealing the ignition wires with silicone sealant or caulking. (a little dab will do ya) check with a local mechanic about "weather proofing" your CA car to deal with the inclement weather. Under harsh rainy conditions I have gone so far as to dry out an engine in a garage with a hair dryer. (don't laugh, it worked)

Final thoughts: how old is the O2 sensor? Does tapping on the flow meter with a screwdriver help? Are ALLL the FI connections looking good and are ALLL the grounds cleaned? (yes, including the PITA at the top of the bell housing)

That is all I can come up with 4 now. Between this and Johns suggestions you should be able to get a handle on this. Keep us posted. You do know about http://www.clarks-garage.com/ yes? You do have manuals, yes?

Gary2397 · 04-07-2009, 08:38 AM

Sorry, I got bad allergy and cold could not got back in tech forum soon.
But I will get you guys posted.

Gary2397 · 04-15-2009, 10:50 AM

End up replacing unnecessary rebuilt alternator, now with new battery
from AutoZone. I got good start and voltage reading, but still has that
hesitate during cold temperature outside.

Coolant temp sensor tested at 2.2K Ohms after overnight park in
the garage. An O2 sensor was replaced last year less than
20K miles on it. Rebuilt AFM from Pelicanparts a year ago.
Coolant temp sensor was replaced several years back.

Got 12K miles on Denso Iridium spark plugs. Replaced new anti-freeze
coolant approved by VW and other European vehicles.

I thought it might be gas issues, here in OR , the gas station mixed
10% with ethano.

nynor · 04-15-2009, 05:30 PM

my '83 and my '88 951 had/have hesitation when not warmed and it is cold outside. i just work with it.

SolReaver · 04-16-2009, 11:22 AM

OK, this is a tough one...Luckily it is not a major prob...But, It would annoy the poo out of me if it was MY car.

HOW cold? I mean...Cool, Brisk, Brrr, OMG it is freaking cold, or Antarctica. a temp range might help.

What does it FEEL like? fuel starvation? Mixture? Skipping? Do you have one of those aftermarket potentiometers on your FI system for performance?

Could you be so kind as to (I know it is weird, but I am grasping here) bring your coil in at night and keep it warm, then install it in the AM and see if a warm coil makes the cold problem go away? (this happened to me, it drove me buggy for months) You could do the same thing with the battery, but that is new, so I am thinking it is OK.

I was really betting on a temp sensor or connection.... you are sure ALLL connections and grounds are good, Yes? All Vac stuff good? Can you get a couple of gallons of aviation fuel to test the ethanol thing?

Nynor: same prob...up for working to a fix? How many temp sensors on Gary's engine? Just the one, or is there a t2 like on some FI? My 924S not here, so I can't look.

nynor · 04-16-2009, 01:52 PM

i believe just the one. there is also a temperature valve (i can't remember what it is called) with a vacuum line in and out that threads into a coolant pipe at the back of the cylinder head.

this has been discussed before and, IIRC, the consensus was that these cars are warm blooded and don't usually run extremely well until they have warmed up a bit.

SolReaver · 04-16-2009, 07:29 PM

Alrighty then Nynor,

If that is indeed the case. And the temperature we are talking about is "OMG it is freakin cold out here" then may I suggest a block heater?

nynor · 04-16-2009, 08:53 PM

you can suggest it. i don't mind it hesitating for a minute or so while things are warming up. its not like it is so cold the car won't start....

TibetanT · TibetanT's Garage

Portland, OREGON is a very damp place at times. I lived in Vancouver, WA for about ten years. My guess(es) are:

1) The distributor cap has some moisture inside prior to starting in the morning. (maybe)

2) My best guess is: The ethanol gasoline is condensing the moisture inside the gas tank which essentially adds water to the system.

My advise at this point: Try draining, or running most of the ethanol gasoline out and put in some good 92 octane Chevron Techron gasoline...full tank of it. Then, take a run on the bridges around Portland, say three times. You should see a difference. Also, if the car is being parked outside with the rains that I remember in the area, you might want to get a car cover for it. That may help as well.

Good luck and have fun on the bridge run. I miss that.

Gary2397 · 04-18-2009, 10:35 PM

It happens when it is very wet and cold I would say aroun under
55 degrees. It felt like power starving. I do not think it is ground issue.

The car had Jacobs High Energy Coil ( round shape) with ballast
resistor installed externally.
I usally put Shell 89 at all times, last week I switched back to Chevron.
It seems to change littlebit.

I do not remember exactly, but I think I did run across this cold issue
info in the Alldata.com.

Gary2397 · 05-04-2009, 12:34 PM

After all frustations winding down. I decided to put its OE parts back
like Bosch spark plug wire, ignition coil and took out stock replacement
K&N air filter and put Wix air filter back on.

Also, last week I went to muffler shop got straight through stainless
muffler over Dynomax that I had installed before.

Carefully readjusted the TPS with multimeter based on Clarks-Garage.
The performance seems promising since it has over 200K miles on it.
My lesson was that after replacing above mention parts with the
after market , hope the car will go faster and got more power.
Actually, the performance got even worse.

From now on, I need to ask myself twice why fix or replace something that
is still working fine. I mean excluded the muffler.
I want to thank you all for giving me some advices.