Cam Surge / Stutter / Miss
Thread Starter
On The Tree
Joined: Dec 2004
Posts: 119
Likes: 0
From: Brighton, TN
Cam Surge / Stutter / Miss Here not too long ago I installed a CC503 cam and it cranked fine and runs fine in the upper rpms but down low I have a surge issue almost like a miss. When I described the problem in a earlier thread someone mentioned cam surge. So I started looking up cam surges and that sounds just like my issue. But the more I drive it the more I fill that this little cam can’t be this bad. I started to look up stuttering and so a lot of folks mentioned O2 sensors. Well I know I haven’t replaced mine in 8 years so tonight I unplugged them and drove the car and I didn’t have any more stuttering at all it was all smooth. My question is when disconnecting the O2 sensors what all does that do? Do you think my O2's are shot? Here is a link to the post that i started about the surge when i installed the cam. http://www.camaroz28.com/forums/showthread.php?t=631681
Thanks in advance and sorry for the long post
Thanks in advance and sorry for the long post
When you unplug your cars o2's the car switches back to open loop. Which means the cars fueling is running off of default settings programmed into the pcm. Also known as speed density. Try replacing the o2's first, but most likely you have a header gasket leakin. Or you might have a leak at the collector(s). Also vacuum leaks will cause this. I have been battling this same issue. When you hold the throttle steady while cruisin the car bucks a lil. Step in the gas a bit, pulls steady! I bet if you scan your car's fuel trims they are way out from 0 at cruise/idle.
my little hotcam has cam surge. with the stock a4 trans it would surge bad if i went from park to "Drive" and kept the car sitting still. once i started rolling it would go away. when the converter would lock up at 47mph it would buck a little. since the rpms are so low like 1500rpms. it wasnt alot but i noticed it. my mail order tune was crap!
might be the tune or its normal? does the surge go away if you cruise at a higher rpm?
might be the tune or its normal? does the surge go away if you cruise at a higher rpm?
Last edited by Badazz 97 TA; Sep 21, 2008 at 11:20 AM.
Basically by unplugging the o2's, your pcm switches back to open loop. The pcm in open loop commands more fuel at low rpms/idle. This is why you have no surge in open loop. When the pcm switches to closed loop, it uses the o2 sensors to maintain stoich 14.7:1 afr. This is sometimes to lean for some cams and causes surge. It also can be a exhaust leak lettin air enter the exhaust, which hinders the o2's readings, which will cause surge. A hands on tune might eliminate most of the surge, being there are no exhaust leaks.
Thread Starter
On The Tree
Joined: Dec 2004
Posts: 119
Likes: 0
From: Brighton, TN
That makes since but I can’t believe that cam surge would be this bad with this cam. When I have the 02s unplugged I can feel very very little surge something I would call normal. Anyone in the memphis area that can ride with me and tell me if this is normal?
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Thread Starter
On The Tree
Joined: Dec 2004
Posts: 119
Likes: 0
From: Brighton, TN
Can someone take a look at my datamaster log file for me?
http://gh94z28.diinoweb.com/files/
It is the 092208.csv Thanks in advance
http://gh94z28.diinoweb.com/files/
It is the 092208.csv Thanks in advance
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On The Tree
Joined: Dec 2004
Posts: 119
Likes: 0
From: Brighton, TN
Update This seems to be a throttle position issue to me now. It doesn’t seem to be anything with a certain rpm. This happens when the throttle is at a certain throttle position which is very light acceleration in any rpm or speed. Does anyone have any suggestion? Thanks
When I first got my car back it had some cam surge, but that went away after driving a bit. Also you could get the tune touched up wich should help alot as long as there is not another problem causing the same symtoms.
Launching!
Joined: Oct 2006
Posts: 271
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From: Sweden
I had surge with my old 224/224 cam on a tight lsa, but only at that light throttle position you are describing, after a few weeks of driving I learned to not have the throttle at that position and had no problems with it.
My **** does the same thing, with the CC306. It will do it under a real light acceleration, or if I try and hold a steady RPM like 4000 while driving. As soon as you get in it, it goes away. I do have a minor header gasket leak at the moment, but it has always done it since the cam was put in, and I didn't have an exhaust leak then. I also put new o2 sensors in immediately after the cam. And I still have it. The only thing I haven't tried is unhooking the o2's. I would really like to get rid of this if it is possible. If it is cam surge so be it...otherwise, I want it gone.
D
D
Launching!
Joined: Oct 2006
Posts: 271
Likes: 0
From: Sweden