Slightly rough idle ... Normal?
Thread Starter
Race Director
Joined: Apr 2001
Posts: 19,329
Likes: 16
From: Saint Augustine, FL
Mid-TN Events Coordinator
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
Slightly rough idle ... Normal?
I'm not even 100% I have a problem, but when my car is idling, it's a little rough. It's not bad by any means, and I have always seemed to have had it since I bought it (with 17K miles). The only reason I brought it up is the other day when scanning at cold idle (open loop) the car is pretty darn smooth. The moment it goes into closed loop it gets rough. The O2 sensors look to be both working, the plugs and plug wires are new, I use good gas, etc.
I really am just looking for a "this is normal" reply. I really want to make sure everything is 100% before I get my headers and LS6 intake put on.
Thoughts?
I really am just looking for a "this is normal" reply. I really want to make sure everything is 100% before I get my headers and LS6 intake put on.
Thoughts?
Melting Slicks
Joined: Nov 2003
Posts: 2,898
Likes: 5
From: Plainfield, IL
Try this if you can reach the 02 plugs. Totally disconnect your front 02 sensors and drive around for a bit. When I had my old 97 Z28 I noticed the car run MUCH smoother in open loop all the time and like you said as soon as closed loop kicked on and it read from the 02's the idle became more rough. You will get a engine light on but that doesnt matter.
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Intermediate
Joined: Oct 2005
Posts: 47
Likes: 0
I noticed that too! Woo Hoo!!
As a former hot rod drag racer and builder, I can tell you that it is what used to be known as "lope". It comes from the cam lobes having a wide overlap. The more overlap, the worse it is. Also, the worse it is, usually the more powerful the car is. This allows for more efficient VE at high RPMs. The LS1 was designed to make it's power upstairs, so a lopey cam makes sense.
I love it!
As a former hot rod drag racer and builder, I can tell you that it is what used to be known as "lope". It comes from the cam lobes having a wide overlap. The more overlap, the worse it is. Also, the worse it is, usually the more powerful the car is. This allows for more efficient VE at high RPMs. The LS1 was designed to make it's power upstairs, so a lopey cam makes sense.
I love it!
