Guest bastaad525 Posted May 20, 2004 Share Posted May 20, 2004 Spork - yeah this is a vacuum leak. Air can circulate freely thru the engine. Your valve cover is now open to atmosphere, allowing air to go in and out as it pleases. However, your crankcase is connected to your intake manifold, where, under vacuum, the intake will suck air in from the crankcase. So air can now enter in from the valve cover, circulate down into the crankcase, and get sucked into the intake manifold as unmetered air. One thing I'm not sure about is how SDS measures air, so this may not apply, but with a stock EFI system, with only the air flow meter to measure air, air from the crankcase would be entering the system well past the point where the AFM is measuring so would be unmetered air and cause you to run lean. Quote Link to comment Share on other sites More sharing options...
spork Posted May 21, 2004 Share Posted May 21, 2004 It reads air with a map sensor connected to a port off the manifold...so there shouldn't be any false air problems, but thats why I was asking to make sure... James Quote Link to comment Share on other sites More sharing options...
mobythevan Posted May 21, 2004 Share Posted May 21, 2004 If you have an air leak on a MAP sensor system it will cause your fuel map to be skewed won't it? It is kinda like having a fast idle valve turned on all the time. Seems like it will cause an offset during tuning of the system. Your right that it won't cause a lean condition or anything because MAP system will add the correct fuel, just cause higher idle and not the right amount of vacuum at idle I guess?? I want to know the answer to this one now. Quote Link to comment Share on other sites More sharing options...
spork Posted May 21, 2004 Share Posted May 21, 2004 well, I pull 22 inches of vaccum at idle....so I don't think thats any problem there... Quote Link to comment Share on other sites More sharing options...
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