Car surges at slight throttle
Thread Starter
Instructor
Joined: Nov 2010
Posts: 106
Likes: 0
From: Cibolo TX
Car surges at slight throttle
Looking for some ideas, My car surges under very light throttle at crusing speed in all gears. Only mods are headers, exhaust and CAI and a tune. Under med to full throttle car runs great, idle great just when i am going at cruse speed where very little throttle is needed i get a bad surge or lurching. Wondering if the throttle position sensor has anything to do with it or if the tuner can smooth this out, is really getting on my nerves now. Thx for any advise
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Thread Starter
Instructor
Joined: Nov 2010
Posts: 106
Likes: 0
From: Cibolo TX
No codes, happened after i put the car back to stock after having a SC removed and new motor installed after No 7 piston let lose. I checked the air bridge and all conections are tight, installed a vararam and headers and did a tune. Never had the problems before but alot of things were changed in the car. Can a tune smooth this out? Does the old trick of spraying carb cleaner work with these new cars, that is how i found vac leaks on my old muscle cars. Im am new to these computer controlled cars.
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
My LS1 has been massaged and tuned so it's not a direct comparison but it surges below about 1700 RPM. If I'm cruising in 6th below about 1800 RPM and attempt to accelerate, INST MPG drops and some surging occurs. Solution? Shift to 5th and climb the torque curve above 2200 RPM= more power, better mileage and no surging.
Instructor
Joined: Oct 2006
Posts: 122
Likes: 0
From: Georgia
Your tune is not calibrated properly. This is the result not adjusting the throttle cracker tables, or at least not calibrating them correctly. Ive always been able to get rid of at least 90% of surging with even the most radical cams. If you had a vacuum leak bad enough to cause surging, you would hear a sucking sound and it would idle very weak.
Thread Starter
Instructor
Joined: Nov 2010
Posts: 106
Likes: 0
From: Cibolo TX
all vacumme lines are hooked up and cant hear any sucking sound and car idles great. I am taking it back up to the shop that installed the motor and did the tune and i am sure he will be able to adjust the cracker tables ( not sure what that is). WHat is the best way to clean the Mass Air sensor?
Le Mans Master
Joined: Nov 2005
Posts: 6,993
Likes: 25
all vacumme lines are hooked up and cant hear any sucking sound and car idles great. I am taking it back up to the shop that installed the motor and did the tune and i am sure he will be able to adjust the cracker tables ( not sure what that is). WHat is the best way to clean the Mass Air sensor?
Le Mans Master
Joined: Dec 2008
Posts: 5,414
Likes: 25
From: Texas
mine did this with headers vararam and tune... light surge cruising around 1700 rpm or so...
i installed a vararam power duct and moved the MAF closer to the throttlebody. after this the surge has been gone for over a year..
might be different on your car, but this worked for me.
i installed a vararam power duct and moved the MAF closer to the throttlebody. after this the surge has been gone for over a year..
might be different on your car, but this worked for me.
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
Yeah, it can probably be fixed with a retune.
But, if you want to try a couple home remedies: you can clean the MAF sensor by pulling it out and spraying electronic cleaner on the 3 little coated resistors that hang in the middle. You can use a q-tip, but be VERY careful not to bend them around too much. While you have it out, clean the throttle body blades with spray cleaner. Then check carefully for air leaks around the Vararram. Then, you can jam a rag/tape or something in one side of the Vararram and see if that makes a difference. At least then you will know it's lean/airflow related.
DG
But, if you want to try a couple home remedies: you can clean the MAF sensor by pulling it out and spraying electronic cleaner on the 3 little coated resistors that hang in the middle. You can use a q-tip, but be VERY careful not to bend them around too much. While you have it out, clean the throttle body blades with spray cleaner. Then check carefully for air leaks around the Vararram. Then, you can jam a rag/tape or something in one side of the Vararram and see if that makes a difference. At least then you will know it's lean/airflow related.
DG
Thread Starter
Instructor
Joined: Nov 2010
Posts: 106
Likes: 0
From: Cibolo TX
I thought you could clean the MAF sensor with carb cleaner, guess i will go to walmart and find some electronic cleaner and try that. As for the power duct, i am using the stock air bridge, i will see if a power duct does anything, good reason to get rid of the stock duct anyway! Thanks for the help guys.
Tech Contributor
Joined: Jan 2007
Posts: 19,449
Likes: 1,155
From: Dyer, IN
I thought you could clean the MAF sensor with carb cleaner, guess i will go to walmart and find some electronic cleaner and try that. As for the power duct, i am using the stock air bridge, i will see if a power duct does anything, good reason to get rid of the stock duct anyway! Thanks for the help guys.
Thread Starter
Instructor
Joined: Nov 2010
Posts: 106
Likes: 0
From: Cibolo TX
Cleaned the MAF with MAF sensor cleaner and still the same thing. No leaks with the vararam checked that also. Hopefully the tuner can work it out tomorrow. ALso ordered a vararam power tube.