Bad Vacuum Reading on a 3.0 V6
#1
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Bad Vacuum Reading on a 3.0 V6
I've got a rough running V6 that throws codes (25 and 51). Code 25 indicates that the engine is running too lean. I think code 51 is a switch issue with the A/C or the throttle position sensor (TPS). The TPS checks out ok at idle and wide open, but I didn't check out the steps with a feeler gauge. The air flow meter (AFM) checks out good too. I didn't check out the injectors, the fuel pressure or the oxygen sensor. I am noticing that it has what I believe is low vacuum at the PCV port on the manifold (15"). That got me checking the compression to make sure the rings weren't bad. So far I checked out the passenger side cylinders and got good readings (175, 165, 175). What am I missing? -- Matt
Last edited by wrenchtech; 05-10-2010 at 08:56 PM.
#3
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Make sure that the main intake hoses are not cracked, split, or missing. Mine split underneath right at the throttle body and caused a rough idle, hesitation, and running lean.
#4
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I'm just getting started so it sure couldn't hurt to give the intake hoses a second look. Thanks.
#5
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So I still want to hear what a good manifold vacuum reading should be for the 3VZE. I'm reading 15". I'm not absolutely sure about the accuracy of the gauge but it feels and acts like a low vac situation. I'm thinking a healthy engine should have mid-20"s. -- Matt
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