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

: Reasons for "lazy" starting?


nefarious
17-03-06, 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?

boxman
17-03-06, 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

Superaero
17-03-06, 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.

yaofeng
17-03-06, 08:22 PM
Your fuel pump may be getting old.