Reasons for "lazy" starting? [Archive] - SaabCentral Forums

: Reasons for "lazy" starting?

17th March 2006, 03:22 AM
More a post out of curiosity than anything else - what causes "lazy" starting?

My 9k Aero (95) always takes til the third turn or so of the engine before it catches, hot or cold. My 900 (T16 88) always starts on the first touch of the key. Both engines have shown nigh-on perfect compression test results.

I wondered if it had something to do with the trionic system wanting a signal from the crank position sensor, and waiting until it had seen the missing tooth spin by a couple of times before it'll trigger the injectors?

Do they all do this?

Any other thoughts?

17th March 2006, 06:39 AM
trionic has no idea of the position of the crankshaft until the engine is turning over, it then messures the ironizasion in the cylinders to deturmine where the crank is and which piston is on compression stroke, so it has to turn over a few times to find this out

17th March 2006, 07:57 PM
Yup, my 86 9000 started at the first twist of the key, almost before one rev completed. The 97 Aero takes several turns to fire. I think the fuel injectors don't open until the spark is ready.

17th March 2006, 08:22 PM
Your fuel pump may be getting old.