986 stalls at start up

[barthol]

Hi All,

Just checked the TEMP sensors

Both the intake air temp, the cooling water temp , the engine compartment temp and the oil temp is around 20 deg C , when the car has been standing over night ( the same as the ambient temp.

As soon as I start the car they starts to climb, Water and oil fastest intakeair temp is climbing slower together with the enginecompartment temp

Temps actually looks fine, and according to the heat up of the engine.

For the vacuum there is no significant resistance inn removing the oil cap not cold nor hot?

If I start the engine from Cold ( it hs been standing over night) without touching the gas pedal it stalls and dies, on the 6-7 attempt it starts running erratically at 500 rpm and after 10-20 seconds it increases to 900 rpm and runs fine.
When it warms up it idles steady at app 750 rpm.

If I at the cold start applies the gas and takes the rpm to 1500 RPM and keep them there for a few seconds then it will immediately idle at 900 RPM when I let go.

In general the car runs fine , no oil consumption , nice and clean acceleration, gas milage is app 10 km/liter

as soon as the car has been started I can restart it without touching the gas??

can it be bad spark/s , Coils acting up when cold??

BR
Kim

[blue62]

Originally Posted by barthol

Hi All,

Just checked the TEMP sensors

Both the intake air temp, the cooling water temp , the engine compartment temp and the oil temp is around 20 deg C , when the car has been standing over night ( the same as the ambient temp.

As soon as I start the car they starts to climb, Water and oil fastest intakeair temp is climbing slower together with the enginecompartment temp

Temps actually looks fine, and according to the heat up of the engine.

For the vacuum there is no significant resistance inn removing the oil cap not cold nor hot?

If I start the engine from Cold ( it hs been standing over night) without touching the gas pedal it stalls and dies, on the 6-7 attempt it starts running erratically at 500 rpm and after 10-20 seconds it increases to 900 rpm and runs fine.
When it warms up it idles steady at app 750 rpm.

If I at the cold start applies the gas and takes the rpm to 1500 RPM and keep them there for a few seconds then it will immediately idle at 900 RPM when I let go.

In general the car runs fine , no oil consumption , nice and clean acceleration, gas milage is app 10 km/liter

as soon as the car has been started I can restart it without touching the gas??

can it be bad spark/s , Coils acting up when cold??

BR
Kim

Are you reading the temp from your instruments on the dash.? Or from a scanner hooked to the OBD port? if you are just taking readings from the dash you need to hook up a scanner to the ECU via the OBD port. sounds like the signal from sensor to dash is fine but you also need to know what the ECU sees.

Do a vacuum test with a vacuum gauge cold and hot. Reading should be 19-21 with a steady needle. I see your in Denmark so you may need to change that reading to a metric number. If that is good I would start looking for things that can affect fuel or air when cold.

That car should have a throttle position sensor might want to check that signal with a scanner right as you start it cold, see if it gives an erratic signal. But pin the vacuum readings down first.

After you are sure of good vacuum readings try this as a check.
with the engine dead cold unplug the MAF sensor (This will force the ECU to go to a set fuel MAP). Try to start the engine. If it starts and idles fine that should tell you it is fuel related.


get back to us with what you find.

[blue62]

I had some additional thoughts on your cold start problem.
The fact that you have to try 5-6 times to get it to start when dead cold says your fuel/air mixture is to lean for cold start.
Engines need a richer mixture for cold starts then they do once warmed up.

I am wondering if there is a problem with your throttle body butterfly when dead cold.
you say once you bring the RPM up for a few seconds everything is fine.
so as a test the next time you try to start it after it has sat over night.
Press the gas pedal all the way to the floor then take your foot off of it and see if it starts normal. what I am trying to test by having you do this is to see if the butterfly position in the throttle body is linked to the problem.