Surging with high overlap cams any solution?
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From: Port Tobacco, MD
Surging with high overlap cams any solution? Has anyone figured out why cams with alot of overlap(10 degrees +) tend to surge @ low RPM and low throttle position? I'd love to find a solution.
Phil
Phil
Mine only surges for a couple of seconds on initial cold start (40 degrees or less). Otherwise it's good. I have no problems in gear while driving. I assume you've tried all of the usual adjustments?
The know it all's know it all
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Originally Posted by Phil99vette
Has anyone figured out why cams with alot of overlap(10 degrees +) tend to surge @ low RPM and low throttle position? I'd love to find a solution.
Phil
Phil
Originally Posted by SSpdDmon
That is usually corrected with a little more (steady) timing than stock, the right fueling, and some tweaking to the cracker/follower tables.
Is this car running in open loop...I assume so....
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From: Sunny London, UK
Open loop speed density
Also take a look at something like efilive os5 with alpha-n fueling. So MAP and MAF dont mess you around.
Loads of guys have had excellent results with that. You can use it say under 1200 RPM and return to MAP SD mode over 1200rpm etc.
Also take a look at something like efilive os5 with alpha-n fueling. So MAP and MAF dont mess you around.
Loads of guys have had excellent results with that. You can use it say under 1200 RPM and return to MAP SD mode over 1200rpm etc.
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From: Port Tobacco, MD
Its running closed loop, I wonder if the O2s are causing it to surge.
When I say surge....
Drive along in 4th gear @ 1200-1600 Rpm with little or no gas the car will buck or pulse. Every car does it, big overlap seems to do it more.
Phil
When I say surge....
Drive along in 4th gear @ 1200-1600 Rpm with little or no gas the car will buck or pulse. Every car does it, big overlap seems to do it more.
Phil
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Verdad Gallardo The know it all's know it all
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Originally Posted by Phil99vette
Its running closed loop, I wonder if the O2s are causing it to surge.
When I say surge....
Drive along in 4th gear @ 1200-1600 Rpm with little or no gas the car will buck or pulse. Every car does it, big overlap seems to do it more.
Phil
When I say surge....
Drive along in 4th gear @ 1200-1600 Rpm with little or no gas the car will buck or pulse. Every car does it, big overlap seems to do it more.
Phil
The know it all's know it all
Joined: Oct 2006
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Originally Posted by ringram
Open loop speed density
Also take a look at something like efilive os5 with alpha-n fueling. So MAP and MAF dont mess you around.
Loads of guys have had excellent results with that. You can use it say under 1200 RPM and return to MAP SD mode over 1200rpm etc.
Also take a look at something like efilive os5 with alpha-n fueling. So MAP and MAF dont mess you around.
Loads of guys have had excellent results with that. You can use it say under 1200 RPM and return to MAP SD mode over 1200rpm etc.
So you are saying that your cracker being too low causes you to have this problem? Could you post the values that you are running in the cracker. I have my cracker completely zeroed out. I have the problem before I zeroed the cracker but I never really played with the values. I am most interested in this. I wouldn't mind looking at your folower table also if possible. I have HPTUNERS but if youare using something else, just e-mail me an excel or word doc or post the raw data here. Thanks in advance. bellos98@yahoo.com
Originally Posted by Sean Collins
The problem is not the MAf. The problem is that most tunners have zero clue as to what they are actually doing.
You must remeber that 02 sensors only measure oxygen content. to really figure out the Af ratoi you must figure fuel flow and have an actual measure of airflow. SD fixs nothing.
by now i should be able to map airflow calculated from SD mode onto the MAF table, but back that i didn't know how to do such tricks. more traditional MAF tuning tricks just wouldn't get it even just in the ballpark. i'm guessing that was reversion saying hello--rare but it does happen
If any of you guys are interested, please check out this thread with the problem that I am having pertaining to this subject. What really kills me is that the cam that I am running is not that big (for a 402) compared to some others that I have seen that claim to have no issues with surging. Any input would be greatly appreciated. This vehicle needs to become my daily driver sooner than later as I am turning in a lease. It is very painful to try and slip a race clutch (Spec 5) in order to smooth the bucking in the problem areas. Thanks in advance.
http://www.hptuners.com/forum/showth...6386#post66386
http://www.hptuners.com/forum/showth...6386#post66386
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
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From: BFE
Curious find by Jimmyblue who noticed the spikes and lows in stock cracker table.
Left is stock and right is smoothed out.
It helped me tremendeously.
https://ls1tech.com/forums/pcm-diagnostics-tuning/456413-weirdness-throttle-cracker-stalling-fix.html
Left is stock and right is smoothed out.
It helped me tremendeously.
https://ls1tech.com/forums/pcm-diagnostics-tuning/456413-weirdness-throttle-cracker-stalling-fix.html
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From: Bergen County, NJ
Originally Posted by SSpdDmon
That is usually corrected with a little more (steady) timing than stock, the right fueling, and some tweaking to the cracker/follower tables.