"Cold" start prob with the old NG900

"Cold" start prob with the old NG900

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Prof Beard

Original Poster:

6,669 posts

234 months

Saturday 30th December 2006
quotequote all
Hi all

I've just posted this on Saab Central, so I thought I'd post it here too

Our NG900S is misbehaving on "cold" starts.

The problem varies slightly, but boils down to:

Car may start OK or be reluctant to start but then start.

Once started car idles OK but then "struggles" once put into gear (it's an auto) and when pulling off and will sometimes "putter" to a halt. After a bit of this, the car usually starts running OK and will remain so for the rest of the day.

This morning was an extreme example - car took three lengthy attempts to start. I then let it run for bit until the engine had begun to warm up and backed out of the drive. As soon as I selected D it struggled and died as soon as I depressed the throttle. It was reluctant to restart but did and then stopped in the same way once it had restarted. It then refused to start - turning over ok though.

I left it for a couple of hours and then it started fine and drove fine for the rest of day.

Any ideas anyone?


Edited by Prof Beard on Saturday 30th December 22:49

wadeski

8,336 posts

220 months

Sunday 31st December 2006
quotequote all
damp wiring? DI cassette?

/leaves before the techies who know what they are talking about come in hehe

Prof Beard

Original Poster:

6,669 posts

234 months

Sunday 31st December 2006
quotequote all
Today it started first go, and apart from one "stutter" - cured by a throttle blip - idled fine. I backed it up and down the drive a few times and then drove off (one single misfire on first driving off) - from then absolutely fine...

The car lives out doors - is there a favourite "damp attractor" on these cars or possibly something which could cause a fuel problem triggered by damp? It seems to be worst when the car left for a day or two...

nicecupoftea

25,310 posts

258 months

Sunday 31st December 2006
quotequote all
Any fault codes come up on Tech2?

When was the fuel filter last changed?

900T-R

20,405 posts

264 months

Sunday 31st December 2006
quotequote all
Sounds like a case of slight injector incontinence... and the engine borderline flooding from condensated fuel in the chambers on start up the next day as a result. But then again this is a highly unscientific guess and I've had a champagne or two, so I'm probably talking out of my a**e as usual...

Prof Beard

Original Poster:

6,669 posts

234 months

Wednesday 3rd January 2007
quotequote all
So far, perceived wisdom from Saab-world seems to suggest the engine-coolant sensor, or possibly a leak in the inlet manifold gasket. Evidently both can cause "chugging" when cold.

Have ordered a sensor as they are cheap and will report back. (Note this is a NA car - there are other things on the turbo models which can also cause these symptoms evidently)