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Turbo or non turbo? Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Sat, 27 Dec 2008 22:26:30 In Reply to: Check engine light, Jims900S, Sat, 27 Dec 2008 17:07:57 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The turbo engine has the LH2.2 system. The non-turbo has the LH2.4. What's the difference? You can read out the fault codes of the LH2.4 with no special tools. The LH2.2 (Turbo) requires a special LH code reader that only a Saab mechanic would have.
The CEL is the only way the engine control can communicate with the outside world, so any number of things will trip it. Yes, knocking will cause the CEL. Since it's knocking, I'm assuming it's a non-turbo; the turbo reduces boost to deal with knock.
If it's a non-turbo, it has the EZK system with a crank position sensor - there is no timing adjustment. If it's a turbo, then you can adjust the timing.
All the knock sensor does is adjust the boost (turbo only) and timing (non-turbo). But it has limited authority. If the engine is knocking because it needs a higher octane, listen (literally) to the engine. As an engine ages, and at 21, your engine is old enough to drink legally, it can require higher octane fuel. So make sure your spark plugs are gapped properly, the timing right (if it's a turbo), and use a high enough octane to keep the engine from knocking. If you can hear it knock, that's bad. Knock will destroy the pistons.
That's all true, independent of the CEL. If any sensor goes out of range, it will light the CEL. The LH can keep the engine running well even if some sensors fail, but the CEL is still lit so that you'll get it fixed. If a sensor is on the edge of the fault threshold, the CEL can go on and off.
But since you have a correlation between higher octane fuel and no CEL, it probably is knock.
So - turbo or non turbo?
posted by 76.221.218...
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