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Re: idle long Posted by RS [Email] ![]() ![]() ![]() In Reply to: idle long, Richard M., Thu, 26 Jul 2001 02:03:20 Members do not see ads below this line. - Help Keep This Site Online - Signup |
You probably have a small vacuum leak. It's a common problem in turbos - the rubber vacuum lines get brittle and crack *and* the rubber bushings that the vacuum hose nipples go into the intake manifold and valve cover shrink. The ECU tries to compensate for random idle speed changes from the vacuum leaks and ends up overshooting.
BTW, the ECU disregards the signal from the O2 sensor while the engine is idling (open loop control).
It's easily fixable in most cases (and probably yours), though: Replace all of your vacuum lines and replace the rubber bushings. I got 3.5 mm silicone vacuum hose from NOPI for $1/foot. The bushings cost me about $15 from the dealer - it's less from one of the sponsors. It's also good practise for a 900T of that vintage.
After I replaced the hoses and bushings on him, Br'er SAAB ('89 Turbo) achieved the nirvana of rock steady idle.
Congrats on your acquisition.
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