new to 944s & having cold start problem
 

Hello all!!! I love this site & all the info Ive already gained. I will be here a long time since I have no plans to give up the 944 I recently purchased. Its my 1st Porsche. 1983 944 n/a 5spd. I didnt know what I was getting myself into, but think I can handle the upkeep of this great car. The PO was a total idiot & rarely drove the car. No service history at all! He owned it for 2 years and never even did a tune up! Anywyas, Ive changed cap, rotor, plugs, wires, replaced & or cleaned all grounds & replaced a leaky/corroded fuel line so far. I plan to change the belts & water pump immediately after sorting out this cold start problem. In the meantime I do not drive the car. Please help me troubleshoot my current concerns if you guys can.
#1 Car has cold start problem. It simply wont start with cold engine unless you give it a squirt of ether...then it fires right up and runs fine. If you turn it off right away & engine still cold it WILL start without the ether but takes many cranks to fire up. Once engine is warm it will start every time. ....I noticed that I dont hear the fuel pump running with key & engine not running but once its running I do hear the pump. Help please! I dont have the $$$ to replace every relay & sensor or else I would have them all changed already. Would like to narrow this problem down a bit.
#2 The engine seems to vibrate more than I feel is right. I have checked the motor mount/ crossmember clearance they seem fine. The engine does not appear to vibrate or move but you can feel the vibration. Will new belts that are properly tensioned solve this?
Thanks a bunch!

I venture to suspect the fuel pump check valve. No fuel pressure at the fuel rail and injectors after sitting and fuel draining back to the fuel tank.

Yes, check the pressure at the fuel rail after you shut it off. Then check it again a good time later.

Balance belt could be off 1 tooth maybe? It could possibly help..but you have to do it anyway so who cares.

I tend to agree on the fuel pump check valve. It's on the fuel filter side of the pump. Replace the fuel filter too.

Fuel pump runs when cranking and when the engine RPM's are over 200. You can lean out of the car with your head down and hear the fuel pump shut off right after you stop cranking -- when the engine does not fire up. This is a safety thing.

If you don't hear the fuel pump then first thing to replace is the DME/fuel pump relay. Always best to keep a spare DME relay in the glove box.

As the whole injection system relies on good connections I see where you have cleaned the ground. Good. If you didn't clean the terminals at the battery do that too.

There are two types of engine vibrations. One is a low rumble corse like vibration from collapsed engine mounts. One quick way is to stick your hand between the oil pan and the cross member. If you can just get the tips of you fingers in there then the mounts are shot. The other type of vibration is from the balance shaft belt being off a tooth or one of the balance shaft pulleys on 170 degrees out. This is a very high pitch vibration along the lines of the large body massagers. You can put your hand on the black cover of the AFS and feel it at an idle.

Thanks for all the fast asnwers! I guess the 1st thing for me to get would be the fuel pump check valve since you all agree with that. I will also change the filter while Im there. And will order a spare DME relay since I continue to read about that part being notoriously faulty. I dont really have any import speciality stores close by & Im weary of getting parts from my local Napa & CarQuest. Do you guys get parts from stores like this? ...I will probally get the check valve from Pelican since its easy enough to just click away plus Im not in a hurry with this car. .......SoCal, suppose this vibration is from the balance shaft belt being off a tooth or one of the balance shaft pulleys on 170 degrees out...will this be obvious to me when taking apart & when putting everything back together so I know its right? Im a timing belt virgin but am an acomplished "american car" mechanic so I have confidence I can get this done with patience. I have acess to the special tools as well but nobody to ask question to. Go figure. I have a shop close by with the tools but no knowledge on 944s they agreed to let me use their tools. Very nice of them, but Id still rather pay than have to do it myself. But then again experience & knowledge is what I thrive on.

If you have wrenched a while on cars, brakes to engine overhauls, then you most likely will have little trouble doing the belts and such on the 944's. Just attention to detail and procedure. Even have a few here that have little experiance that have done a successful job of belt replacements.

The Haynes 944 manuals are a good start for your (and my) year car. Most of us have one and can give you picture by page feed back on your questions.

The 2.5 liter 944 engine is a valve cruncher if/when the timing belt breaks or strips teeth.

If you have someone else do this make darn sure they have 944 (or 928) experiance. This is where the Haynes manual will help you ask those pointed questions.

Order the extra DME from PelicanParts.com. Helps pay for the BBS.

UncleMikey,
I think you'll probably be able to clear up the engine vibration with a belt job, but just a thought....you said you just recently bought this car and aren't going to drive it until the services are done (very good idea, BTW). But something occurs to me....have you filled up the tank? If you are running the PO's gas that's who knows how old it could be causing both of those problems. Just wanted to check.

I had to drive it 200 miles home & did get a chance to run fresh gas through it. I just ordered a fuel filter, fuel pump check & a spare DME relay from Pelican. I will post the results of my start problem once I get the parts & put em on. Thanks for all your helpful advice. .....BTW I hate the Haynes manual, it really leaves out so much important info, but I guess thats why I found this site and will be searching threads often.

Hello.... FINALLY got around to getting the parts on but to no avail of my problem. I replaced the fuel filter, fuel pump check valve & DME relay (my old one was dated 5-83, old huh) and I still have the exact same problem: ....With cold engine, The car will ONLY start with ether spray & then runs fine. Once car is warm it will start on its own no problem after that. Once cold must use ether again. ....Any other suggestions from you guys would be great. Do you think this could be a MAF sensor thing or something else electrical or is it safe to rule that out? I dont have access to a fuel pressure tester either & will probally have to buy one. Is there anything special I need to test the pressure for the 944 before I go buy the wrong tester? Thanks alot!!!!!!

I'm new to 944s, but if this were a 911 I'd check the cold start valve, which is supposed to richen the mixture when the engine's below a certain temperature (thermotime switch).

Emanuel

May need to adjust the sensor clearance. If they are set just a little to far away from the flywheel you will have cold start problems.

FR WILK ..I went & started it with ether today and it idles just like it should. About 1150-1200 at 1st then drops to 950. And its like 20 below outside with the wind chill. Only 15 in my garage and its the same wether its 60 or 0. I always have to use the ether to start. I looked all my fuel lines over real good again and dont see any signs of seeping lines that would make me lose pressure ...SoCal which sensor are you talking about? And how do I know I have the proper clearance?

Do 944s have a cold start valve? I cant find anything on it.

No cold start valve.

I would check the sensor gap as previously mentioned. The other possibility is the cold start system in the DME is not working, this increases injector opening time to provide more fuel at cold temperatures.
Check the fuel system pressure first to diagnose if the check valve (or something else) is faulty. Even if the check valve completely failed the engine will eventually start as the pump pressures up the system.

Which sensor are you guys talking about? And what would be the correct gap?

Sensors. Two of them. The speed and reference. On the back side of the engine on the top of the bell housing.

These tend to be stuck in the bracket and the bracket bolts frozen or hard to get to.

Check out www.clarks-garage.com and www.frwilk.com for info.

Also search this forum for "sensor adjustment". Been may extensive write ups on it.

I think this is a good hunch, for the following reason.

My '83 928 (which has the same head and injection system as my '84 944) had the same symptoms. It would not start unless I encouraged it with ether, and then it would run fine.

I replaced the Temp II sensor, but I didn't know there was a "Thermo time switch", which looks just like the Temp II sensor on a 928. Both of these gizmos are nothing more than a signal sensor for a water temp gauge, but they are connected to the COLD START VALVE. In other words, if the Thermo time switch on a 928 goes out, the CSV won't work. Once I got the Thermo Time Switch installed, blammmmm, the motor wants to jump out of the engine bay when I touch the starter.

Since the 944 uses almost "identical" technology, I would suspect there is something in the system affecting the cold starting system. Since I'm away from all of my manuals, etc., that's all the help I can offer now.

good luck, P

Close, but no banana. The 944 doesn't use a CSV nor does it have a thermo time switch. It does have a coolant temp sensor and an intake temp sensor (which is in the AFM). It's possible the coolant temp sensor is faulty, and it's also possible the AFM is not registering that the engine is cranking and therefore no-start. Lots of possibilities, needs more diagnosis.

Im going to check the sensors & adjust them sometime tomorrow. I will post what happens.