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SVT Shelby GT500
Need help/advice on what to do about a vacuum issue after JDM cam install
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<blockquote data-quote="FEARSNO1" data-source="post: 14290151" data-attributes="member: 9770"><p>so tore the motor down and replaced oil pump gears, head gaskets, deleted the EGR (kept the SIP sensor), KB 168 mm Oval TB and put in JDM Super Stock Camshafts. </p><p></p><p>The Problem: </p><p>the car idles great, drives great, and is making power (haven't dynode yet). but my only issue is that now at idle I'm only getting 4in of vacuum below the blower, I've checked with both a mechanical and a electrical gauge that self calibrates as every power cycle, and both show the same. I've contacted JDM, KB, Revan Racing, Jon Lund, and nobody seems to know why it is so low. JDM says it should be 8-12in of vacuum, I have done a compression check and that was fine, I have tested every vacuum line on the motor for leaks and found a couple but made no difference, fuel trims are right where they are supposed to be and show no sign of unmetered air entering the motor. so I have been stumped to say the least. now the tricky issue is that before the blower in the intake elbow I read 12in of vacuum but below the blower its only 4in.(which is where the reading is supposed to be taken from) I also replaced the bypass valve to KB's low vacuum version and have verified that it is opening/closing as required. So I am lost as to why I am having this issue. now admittedly if I didn't have a vacuum gauge on the car I would never suspect that anything was out of the norm!</p><p></p><p>FYI I even went run a test on my buddies 13 GT500 and between the intake elbow and below the blower his shows about a 2in vacuum loss 21 vs 19.</p><p></p><p>any insight would be appreciated</p></blockquote><p></p>
[QUOTE="FEARSNO1, post: 14290151, member: 9770"] so tore the motor down and replaced oil pump gears, head gaskets, deleted the EGR (kept the SIP sensor), KB 168 mm Oval TB and put in JDM Super Stock Camshafts. The Problem: the car idles great, drives great, and is making power (haven't dynode yet). but my only issue is that now at idle I'm only getting 4in of vacuum below the blower, I've checked with both a mechanical and a electrical gauge that self calibrates as every power cycle, and both show the same. I've contacted JDM, KB, Revan Racing, Jon Lund, and nobody seems to know why it is so low. JDM says it should be 8-12in of vacuum, I have done a compression check and that was fine, I have tested every vacuum line on the motor for leaks and found a couple but made no difference, fuel trims are right where they are supposed to be and show no sign of unmetered air entering the motor. so I have been stumped to say the least. now the tricky issue is that before the blower in the intake elbow I read 12in of vacuum but below the blower its only 4in.(which is where the reading is supposed to be taken from) I also replaced the bypass valve to KB's low vacuum version and have verified that it is opening/closing as required. So I am lost as to why I am having this issue. now admittedly if I didn't have a vacuum gauge on the car I would never suspect that anything was out of the norm! FYI I even went run a test on my buddies 13 GT500 and between the intake elbow and below the blower his shows about a 2in vacuum loss 21 vs 19. any insight would be appreciated [/QUOTE]
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Need help/advice on what to do about a vacuum issue after JDM cam install
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