Carrera 3.2 cold start problem

[frankw]

My 3.2 no longer starts when it gets cold outside.

If I park the car in my heated garage for the night, it starts just fine and works as it should, a dream!
If I leave it outside for the night, it wont start.

I went to Croatia this summer, it started everyday at first crank even when parked outside, temperature was never below 20. I add 3.000 km on it during this trip, no problem, normal fuel consumption, no smoke, nothing.

Some weeks before, I went to london, one night out and it didn't start. Temperature was below 10... I left the car outside waiting for some sun and outside temperature to go up and at some points, it started. Now it's winter here, it no longer start except when in an heated garage.

When I squirt a bit of starting fluid in the air cleaner... It eventually starts and works fine. Idle is fine as well. One more thing, when It starts and the engine gets warm, you can stop it and restart it, it will work just fine even when below zero.

Any ideas?

Frank

[DRACO A5OG]

How is the health of your battery, what is the current voltage at the battery out in the cold before you start it?

Starter Fluid? have you swapped your DME relay to take the fuel pump out as a suspect?

[aerodyn930]

Hello Frank, As the previous post suggests , Verify if your cranking speed is normal at the low temps, Switch your DME relay,
Another possibility is a failed cylinder head temp sensor ( low resistance) , This will cause a lean condition that may explain your difficulty at very low temps,
Porsche offered a upgraded sensor, It would be interesting to know if you still have the original version,

Let us know what you find, Lou

[frankw]

Thanks for your help.

Battery is good and I changed the DME relay. No impact. It cranks fine, just the same at low or high temps. As I mentionned, if I spray starting fluid in the air intake, It will start. Then, it works just fine as far as performance, fuel consumption and idle are concerned.

I will check the temp sensor today, I keep you informed.

Frank

[db_cooper]

The speed and reference sensors can be temp sensitive. One or the other will not give a strong enough signal when cold.

The starting fluid will auto ignite (diesel) the engine enough to spin faster..generating a stronger signal from the sensor(s) for the ECU to see them and start the ignition/injection process.

Can't say for sure that is your problem..but I have seen it happen on 3.2s when cold.

[PilotGabe]

Hi Guys, I'm having the same problem. I hate to say that I did exactly what I don't like to see mechanics do. I started replacing expensive parts on the word of so called mechanics that happen to be my friends. We replaced the Fuel pump and check valve because when we checked the fuel pressure at the nut on the fuel rail rite after starting the car with either, it would dribble, with no pressure. NOT. Then we changed the ECU because someone else tells me that several things are not working like a pulse to the injectors and no sound from the fuel pump. NOT. Then we changed the relay next to the ECU. NOT. I guess it's off to the temp sensor now. Have any of you found anything yet?? I might add that we're not talking extreme cold just normal cold starts, I'm in LA, CA.

[cabmandone]

I'm going to say if it will start on either, the speed and reference sensor aren't the problem. I could be wrong. I think I'd focus on the Cylinder Head Temp sensor. It doesn't sound like it's sensing the head is cold and richening the mixture for cold start. I think that's how it works IIRC. I believe there is a way to bypass the CHT but I don't recall how it's done. Do a search and you'll find it.

[steely]

Check the ICV to make sure it's working and/or not sticking - that can contribute as well. Ask me how I know.
It should vibe when on at the least, and if it is, it just may benefit from some cleaning.
Also in my case, I replaced some vac lines, so that may have helped as well.

[DRACO A5OG]

Originally Posted by cabmando

I believe there is a way to bypass the CHT but I don't recall how it's done.

Yes, get a paper clip, cut it in half like a "U" and stick it into the connector. This will bypass the CHTS and car should start if it is the culprit.

Check the OHMs on the CHTS sensor cold and after a run



Jim

OP, what is the actually battery reading at the terminals when cold?

[mysocal911]

Originally Posted by DRACO A5OG

Yes, get a paper clip, cut it in half like a "U" and stick it into the connector. This will bypass the CHTS and car should start if it is the culprit.

Check the OHMs on the CHTS sensor cold and after a run



Jim

OP, what is the actually battery reading at the terminals when cold?

That's the test for a rich no start condition not a lean no start, i.e. the paper clip jumper!

To richen the mixture for a very lean (cold) no start, just disconnect
the temp sensor momentarily while cranking.