Chasing a vacuum leak
07-16-2009, 06:05 PM
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Chasing a vacuum leak Would the gray seal around the MAP sensor cause a vacuum leak. Doesn't seem like it was in the best of shape. It idles fine about 700rpm, throws a po507 code, car runs great. Any help? Thanks
07-19-2009, 06:47 PM
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^^ that is not solving the problem, that is just trying to cover it up. also i do not see how you idea will work, on a stock ls1 f-body the throttle plate is completely closed at idle and it gets all of the air to idle from the little hole drilled in the throttle plate.
i would try to find where the leak is. you do this with some eather (engine starter) you spray it around areas where you think you might have a leak. if there is a leak the idle will jump. don't forget to spray the back of the intake manifold and please do not spray the exhaust manifold.
i would try to find where the leak is. you do this with some eather (engine starter) you spray it around areas where you think you might have a leak. if there is a leak the idle will jump. don't forget to spray the back of the intake manifold and please do not spray the exhaust manifold.
07-19-2009, 07:02 PM
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^^ that is not solving the problem, that is just trying to cover it up. also i do not see how you idea will work, on a stock ls1 f-body the throttle plate is completely closed at idle and it gets all of the air to idle from the little hole drilled in the throttle plate.
i would try to find where the leak is. you do this with some eather (engine starter) you spray it around areas where you think you might have a leak. if there is a leak the idle will jump. don't forget to spray the back of the intake manifold and please do not spray the exhaust manifold.
i would try to find where the leak is. you do this with some eather (engine starter) you spray it around areas where you think you might have a leak. if there is a leak the idle will jump. don't forget to spray the back of the intake manifold and please do not spray the exhaust manifold.
If there was a leak the idle wouldn't be smooth is would jump and surge when the pedal is depressed. The idle screw may be adjusted to far out and the blade is not closing all the way. Or possible the blade is just stuck open to far, did you try to adjust your cables it is possible that your throttle cables could be stuck too. And no this is not just covering up the problem it is an attemp to fix it with the easy things first.
07-19-2009, 07:32 PM
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well, the throttle plate not closing all the way makes sense, but you do not diagnose that problem by adjusting screws. you take off the lid with maf and visually inspect if it is closing all the way or not. otherwise you will just be creating more job's for yourself.
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07-20-2009, 04:38 PM
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First off thanks for the replies. The throttle plate is closed. As far as I know the idle screw has not ben adjusted. It idles smooth, runs great. Is spraying carb cleaner around sensors a good idea? I replaced the plastic port for the brake booster, if that doesn't fix it I may replace the map sensor, I do believe the gray seal was not in the best shape. Of course you can't buy just the seal. MAP sensor $60. I'll find it if the last thing I do. Thanks again
07-21-2009, 11:13 AM
#9
Use propane to find vacuum leaks. Use a small bottle with a torch head and don't liht it. Just turn on some propane and start moving it around the area you think maybe leaking. The idle will rise up if the propane finds a leak. Much safer than using a spray,unless you like calling the fire company.
08-07-2011, 07:40 AM
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Guys I have found that Carb cleaner is easier to detect a leak because the engine bogs. I tried starting fluid but the raise in idle is hard to hear when you are standing by the engine doing this by yourself. One buddy of mine ended up pouring water to find his intake leak..lol he found it.....
08-08-2011, 06:17 AM
#11
If your really worried about a vac leak, buy some vaccume grease. Also there could be a crack in the nipple off if the intake neck that goes to the fuel line.
Don't feel bad, I am chasing down a EVAP code which I am VERY close to having tuned out and not dealing with it any more.
Don't feel bad, I am chasing down a EVAP code which I am VERY close to having tuned out and not dealing with it any more.
