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I installed a new air filter on my '02 SWB Envoy this weekend and wanted to see if it would have any effects on the ease of revving. So while in park I revved the engine, but noticed it wouldn't rev past 4k rpms while the tranny was in park. So I took it out on the road and while in Drive it would redline like normal. I am wondering if it was limited by the ECU while it was in park, or was it more likely the fan clutch was kicked in when I started it and it was in park, and the fan limited the rpms. Any thoughts? Its not like I drive my envoy hard and it rarely sees anything above 3k rpms in normal driving.
 

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2005 chevy trailblazer_ls
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To the best of my knowledgr the ECM won't let it overrev in park.
Yeah and the ECM also makes the rev's really slow to 4,000. If you put your foot on the brake and slowly shift to the middle of park and reverse so that there is not a line under either one so it looks like this PRND321 with none of the symbols underlined and then punch the gas it will now redline and it will do it quickly. Just be careful not to let it slip into reverse while doing this.
 

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Yeah and the ECM also makes the rev's really slow to 4,000. If you put your foot on the brake and slowly shift to the middle of park and reverse so that there is not a line under either one so it looks like this PRND321 with none of the symbols underlined and then punch the gas it will now redline and it will do it quickly. Just be careful not to let it slip into reverse while doing this.
Now I'm not a mechanic, but this may not be the smartest idea in the world... :hopeless
 

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2002 olds bravada
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Gearhead has a video of him free revving his bravada. There's a video of it somewhere..

Typically, there is a rev limiter when in neutral/park that is at 4000 RPM. When in Gear (D), it shifts at 6000RPM but lets say you keep it in 1 or 2, it hits the limiter at 6100 RPM and just stays there until you let go of the gas or shift.
 

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Yeah thats who i learned it from if you try to rev it in Park it takes like 4 seconds just to hit 4000 rpms but if you trick the ECM by putting it between two gears you can rev it all the way up to 6100 rpms in less then a second. As long as you dont let it fall into reverse while you are doing it its fine but if you slip and throw it into reverse you just shortened your tranny life by a few miles lol
 

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The 4k limiter is to protect the transmission and engine from doing neutral slams. I'm pretty sure it limits it in neutral as well.
It will rev to redline if it's in drive or neutral and the truck is rolling at 10 mph or so. Mine tops out at 3 grand in park. I have yet to try what longhorn 262 suggested, but that does sound cool. :undecided I'm just afraid of the truck slipping into reverse at 6,000 rpm in the driveway. :no:
 

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It will rev to redline if it's in drive or neutral and the truck is rolling at 10 mph or so. Mine tops out at 3 grand in park. I have yet to try what longhorn 262 suggested, but that does sound cool. :undecided I'm just afraid of the truck slipping into reverse at 6,000 rpm in the driveway. :no:
It's much easier to slip it into PARK then reverse. I've done it a couple times so far and if you're careful, its almost impossible for it to go back into reverse.
 
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