quick question on idle rpm with comp cam
08-03-2009, 11:38 PM
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quick question on idle rpm with comp cam its a xr281HR 228/230 .571/.573 112 lobe cam in a ls1. it idles at about 1200 rpm, and will hang at about 1500-1750 until i come to a complete stop. is this about right, or should it idle at a lower rpm? just got this car, and checking everything out. it was tuned by chuck at hpe a couple years ago.
08-04-2009, 12:48 AM
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1200 is way too high. Mines at 850 right now. After I retune for my new motor, i'm going to try to get it down to around 7-750 rpm.
You should get it retuned. It shouldn't hang up like that at all.
You should get it retuned. It shouldn't hang up like that at all.
08-04-2009, 10:54 AM
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I have the same cam. My idle is 900 rpm but it also hangs at 1500 or so until I come to a complete stop. The idle control system is very complex and changes can cause instability. Some tuners know how to tame the idle system. I do not.
08-04-2009, 11:26 AM
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i was thinking today, what about a vaccum leak? where should i check? because one of my old mustangs would do the exact same thing, idle hanging at 1500-2000 rpm and then idling 500 rpm or so above where it should have been and it was a vaccum leak.
08-04-2009, 07:14 PM
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if it were a vaccum leak, id have a code in the computer right? i did a full diagnostic at work and didnt come up with anything. only other thing i can think of is iac or something, but its probably the tune, huh?
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08-05-2009, 08:22 PM
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well, we got the idle down to 800, and now it runs like ****.. surges, stalls, you name it. wtf. guess im going back tomorrow to reverse the changes. cant think of anything else to do.
08-05-2009, 09:34 PM
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Old tech, but I have a Comp 280XFI in a L98 383. It took me ages to get my idle from 1500 to an acceptable 950-1025.
Maybe you can bump it a bit and get it to run ok.
Maybe you can bump it a bit and get it to run ok.
08-05-2009, 10:11 PM
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we pulled the idle all the way down to 700, and was loping pretty hard, but it kept surging, so we bumped it to 800. i guess we'll have to go up to 850-900. ive also noticed that the idle will fluctuate 100-200 rpms regularly, and then sometimes really start surging up to 1500 and then down to 500 ish and back and forth and then stall out. im going to try cleaning the iac port tomorrow, and see what happens.
08-05-2009, 11:57 PM
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I still say it's in the tune more than likely. Go to http://www.hptuners.com/forum/index.php search around for what your car is doing. Then find someone that really knows how to tune. Could need more or less air, more or less timing, more or less fuel,etc. Russ K also has an idle config. that is used for start up on the hpt site. So, like already said, try to get all the tuning squared away.
08-06-2009, 01:06 AM
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I believe it has to do with Idle Air Control or IAC tuning...haven't really messed with it yet...but that is most likely your problem...my stock cam LS1 was doing the same thing before it gave up on life so once I put the new cam in I'll address that problem....
08-06-2009, 09:10 AM
#15
I agree, thats a crappy tune. Idle should be 900RPM and not hang at all.
08-06-2009, 09:12 AM
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Did you go back to HPE? Cause it sounds like they dont know what they are doing...take it to a competent tuner. If none are in your local area, go for a mail order tune from ECS or Charlie@RPM Motors
08-06-2009, 11:23 AM
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well today its not surging, or stalling. i dont know whats up. still idles a touch too high for my liking but eh. whatever. ill drive it like this for the time being, and see what happens. eventually ill get my own tuner and do it. ive done tweecer tunes on mustangs and lightnings, cant be much different.
08-06-2009, 11:58 AM
#18
its a xr281HR 228/230 .571/.573 112 lobe cam in a ls1. it idles at about 1200 rpm, and will hang at about 1500-1750 until i come to a complete stop. is this about right, or should it idle at a lower rpm? just got this car, and checking everything out. it was tuned by chuck at hpe a couple years ago.
08-06-2009, 02:10 PM
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tach was found to be off, it was idling at 950 which is what chuck had set in the parameters. id like it to be in the 750-800 range so it didnt sound like a truck idling. oh well.
