Question about Saab 900

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My 1998 900S run fantastic until you come to a red light. While applying the brakes the engine seems to shudder (idle up and down). Now I have an automatic transmission so the idle should be constant regardless. I had the fuel pump changed last year for over 1,000 dollars. I really don't want to eat that expense again. Any ideas what this could be?

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  • djh6721 Mar 09, 2009

    emissionwhiz, Thank You. The solution was perfect. Your advice also promted me to clean the MAC which did require a different cleaner also by CRC. Again thank you very much.

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Try the following it usually cure s this kind of problem
Here is the most common cause of surges and stalls at stops and low erratic idle speed and rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake

Posted on Mar 06, 2009

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