cmlucht Posted January 12, 2020 Share Posted January 12, 2020 I have a 2009 outback xt. Specs. 100% stock. 111000 miles. 91 non eth. I have bad idle like its shaking, it don't matter if its in park n r or drive. I hooked up my obd2 and at idle I am getting a 13 vacuum, is that what could be causing the bad idle? I heard somewhere it should be 17+ on vacuum. Link to comment Share on other sites More sharing options...
awfulwaffle Posted January 12, 2020 Share Posted January 12, 2020 My LGT tends to sit around -18 inHg vac Link to comment Share on other sites More sharing options...
lilredwagon Posted January 19, 2020 Share Posted January 19, 2020 Unless you have a proper boost gauge, the readings through the OBD2 will be different. I monitor my car with Dash Command, and the "boost gauge" is relatively close for boost, but for vacuum it's way off, when compared to my actual boost gauge. If I remember, I'll see what my OBD2 vacuum looks like at idle, but if I recall, it was somewhere around 13 like you're reading, while the boost gauge read 18.5 hg. Link to comment Share on other sites More sharing options...
cmlucht Posted January 19, 2020 Author Share Posted January 19, 2020 I did a home made smoke test and found that the end of one of my fittings was broken, I fixed than and my access port and obd2 are saying 17 . So if I had a real gage I would probably be in the good range now. Link to comment Share on other sites More sharing options...
awfulwaffle Posted January 19, 2020 Share Posted January 19, 2020 Unless you have a proper boost gauge' date=' the readings through the OBD2 will be different. I monitor my car with Dash Command, and the "boost gauge" is relatively close for boost, but for vacuum it's way off, when compared to my actual boost gauge. If I remember, I'll see what my OBD2 vacuum looks like at idle, but if I recall, it was somewhere around 13 like you're reading, while the boost gauge read 18.5 hg.[/quote'] Mine have always been very close. Note that most boost gauges will display boost in psi and vacuum in inHg, whereas the ECU reports both boost and vacuum in psi. That would lead to the numerical vacuum value reported by the ECU to be about half of what reads on the boost gauge. Link to comment Share on other sites More sharing options...
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