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REV HANGING ISSUE
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deim78
New User
| Posts: 1
| Joined: 10/08
Posted: 10/11/08
12:06 PM
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Just installed a cam, heads and also fast 90/90. The car idles at 1100 rpm. The question is if you hit the gas the car will rev higher and takes awhile to get back down to 1100. The fast throttle body was used when I bought it. I didnt know if there was a vacuum or another setting that would prohibit the car not returning to idle right away. All the vacuum lines are connected that I can see, and sprayed around the intake to look for leaks and came up with nothing. Thanks for any insight.
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Posted: 10/15/08
08:19 AM
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It's hard to say exactly what the problem is without knowing the whole history and seeing the car, but I do know that a lot of LS1 cars that have tuned computers have a similar problem. It's just the nature (or imperfection) of the software.
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waynep712
New User
| Posts: 11
| Joined: 06/08
Posted: 10/18/08
09:37 AM
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do you have a scan tool that shows live data????
you need to look at the throttle position sensor voltage, the idle air control counts... the coolant temp sensor voltage.... but not measured at the sensor.. what the ecm displays...
the idle air control counts should be somewhere between 20 and 50... with the engine warmed up and at normal idle speed...
the throttle position sensor voltage should be between .75 volts and 1.25 volts..
the coolant temp should be on the scan tool showing about 210 to 220F..
the idle air control when the motor is revved up goes to 135 to 150 counts... and may take a second or two to come back down...
were you able to set base idle... by blocking the idle air bypass passage with a piece of tape or your finger??
if you don't have a scan too that reads live data...
check out this one from harbor freight, it reads live data on obd2 cars
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=98614
this link shows what normal values should be with a scan tool...
http://econtent.autozone.com:24991/znetrgs/repair_guide_content/en_us/images//0900c152/80/0b/86/3e//large/0900c152800b863e.gif
it will be a big help when you start looking at any scan tool data...
just a few thoughts...
waynep712
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mpayne
Enthusiast
| Posts: 263
| Joined: 10/07
Posted: 10/20/08
04:30 PM
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Thanks for the insight guys, deim78 any news on your idling problem?
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