[Z06] Surging on cruise
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From: Oyen Alberta
Surging on cruise
my 03 Z runs perfect until you get on a slight down grade on cruise. A big hill and it is fine. It holds its speed perfect , it feels like the computer is on and off the gas. Does anyone else have this problem? I wonder if is the combination of a light car, power full engine and a standard trans.
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From: Newberry FL
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St. Jude Donor '07
my 03 Z runs perfect until you get on a slight down grade on cruise. A big hill and it is fine. It holds its speed perfect , it feels like the computer is on and off the gas. Does anyone else have this problem? I wonder if is the combination of a light car, power full engine and a standard trans.
My jerks a bit in low RPMs, I add a little load to it and it is fine.
I know that when I initially installed my VR, things were a bit jerky and the car was not fun until I was at highway speeds. Took some driving to work itself out, but I am not 100% sure what it was doing.
Micah
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From: Oyen Alberta
I just bought the car last fall. drove it about 800 miles this spring. It has a VR, long tube headers and a tune. Some days it runs perfect others it acts up. must be a temperature thing. My car is the same , add a little load and it is fine.
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From: Newberry FL
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St. Jude Donor '07
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From: Oyen Alberta
Does your car have the HALLTECH HONEYCOMB in the MAF? Sometimes turbulent air causes the MAF to have confused readings. It is what it is. More than often, if you have have heavy gusts of wind tunneling into the VR tunnels, it can make your car act strange. It is what it is.
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same problem hre man.. where i live it gets horrible wind and mine was doing it at low rpms all the time as well, 2 things helped the Haltech honey comb took alot of the jerk out then it still did it a little so i figured in theory the air filter should have been cutting alot of that turbulance from the incoming air out so i took the box apart and added my own seal using 1/2" thick weather stripping and it cut WAY more of the jerk out from the wind. i dont think the skimpy little seal they give that thing out of the box works for crap i know i felt literally no tension when i buckled the clips on mine
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From: Newberry FL
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St. Jude Donor '07
same problem hre man.. where i live it gets horrible wind and mine was doing it at low rpms all the time as well, 2 things helped the Haltech honey comb took alot of the jerk out then it still did it a little so i figured in theory the air filter should have been cutting alot of that turbulance from the incoming air out so i took the box apart and added my own seal using 1/2" thick weather stripping and it cut WAY more of the jerk out from the wind. i dont think the skimpy little seal they give that thing out of the box works for crap i know i felt literally no tension when i buckled the clips on mine
My MAF is stock and what blades wrote above is pretty common to what my situation is. The HALLTECH honeycomb helped out a lot, but it still gets jerky/bucky at times with good head winds. Good luck and the honeycomb is only $40.
Micah
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From: Wylie TX --> Less is More, except under the hood !
I had something similar to what your experiencing... At low RPM's cruising around (1500-2000).... I could feel a slight hesitation (like I lifted off the gas periodically).
I found out that the Chevron gas station I ALWAYS went to had bad gas.
Once I filled at another station the hesitation disappeared.
I also noticed recently that when I ran the AC it would take a while for my idle to go under 1000 rpm. Seemed to hang at 1700-2000 rpm for 5 or so seconds at a light. Seems the bad gas was causing that too because I drove this weekend and the idle came right down quickly at a stop light.
Try going close to empty and filling with a different gas station.
Toque
I found out that the Chevron gas station I ALWAYS went to had bad gas.
Once I filled at another station the hesitation disappeared.
I also noticed recently that when I ran the AC it would take a while for my idle to go under 1000 rpm. Seemed to hang at 1700-2000 rpm for 5 or so seconds at a light. Seems the bad gas was causing that too because I drove this weekend and the idle came right down quickly at a stop light.
Try going close to empty and filling with a different gas station.
Toque
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Joined: Sep 2002
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From: Oyen Alberta
I had something similar to what your experiencing... At low RPM's cruising around (1500-2000).... I could feel a slight hesitation (like I lifted off the gas periodically).
I found out that the Chevron gas station I ALWAYS went to had bad gas.
Once I filled at another station the hesitation disappeared.
I also noticed recently that when I ran the AC it would take a while for my idle to go under 1000 rpm. Seemed to hang at 1700-2000 rpm for 5 or so seconds at a light. Seems the bad gas was causing that too because I drove this weekend and the idle came right down quickly at a stop light.
Try going close to empty and filling with a different gas station.
Toque
I found out that the Chevron gas station I ALWAYS went to had bad gas.
Once I filled at another station the hesitation disappeared.
I also noticed recently that when I ran the AC it would take a while for my idle to go under 1000 rpm. Seemed to hang at 1700-2000 rpm for 5 or so seconds at a light. Seems the bad gas was causing that too because I drove this weekend and the idle came right down quickly at a stop light.
Try going close to empty and filling with a different gas station.
Toque
Le Mans Master
Joined: Aug 2005
Posts: 5,375
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From: CA.
St. Jude Donor '13-'14-'15
I assume you are in 6th gear---Which at low speeds on any car with a 3.42 rear end will be jerky--easiest fix would be to downshift to 5th and get the RPM's up--but I realize you are going downhill so not really a good remendy--
The combination of the Varrram and the LT's also add to the issue-- Varrarams change the MAF signal and require special tuning to get your fuel trims at "0" or slightly negative-The LT's change how your 02's work--because the 02 bungs are further aft than the stock manifolds ---you get erroneous 02 readings--Your closed loop (PT) fueling becomes richer--more like 14.2 instead of 14.68--again correctable with tuning
Check to see if when they1st tuned your car if they messed with the "DFCO" settings---deceleration fuel cut-off--Someimes on a hd /cam install tuners will to eliminate dieing wen coming to a stop
Stock setting should not enable it OVER 25 MPH
ALSO you can make an adjustmnet to your "throttle follower " table--
This table either speeds up or slows down the speed of the throttle when closing it--slowing it down would make it HANG ON longer when lifting off the gas going downhill--maybe just enough to overcome the jerking
The combination of the Varrram and the LT's also add to the issue-- Varrarams change the MAF signal and require special tuning to get your fuel trims at "0" or slightly negative-The LT's change how your 02's work--because the 02 bungs are further aft than the stock manifolds ---you get erroneous 02 readings--Your closed loop (PT) fueling becomes richer--more like 14.2 instead of 14.68--again correctable with tuning
Check to see if when they1st tuned your car if they messed with the "DFCO" settings---deceleration fuel cut-off--Someimes on a hd /cam install tuners will to eliminate dieing wen coming to a stop
Stock setting should not enable it OVER 25 MPH
ALSO you can make an adjustmnet to your "throttle follower " table--
This table either speeds up or slows down the speed of the throttle when closing it--slowing it down would make it HANG ON longer when lifting off the gas going downhill--maybe just enough to overcome the jerking
Last edited by tblu92; May 28, 2011 at 03:26 PM.
Burning Brakes
Joined: Apr 2005
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From: Appleton Wisconsin
I had the same problem after I installed VR intake. I bought halltech honeycomb maf screen and i would say 95% of the surge went away. Every once in a great while I will get a slight surge, which can greatly depened on the temperature and humidity of the air.
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From: Newberry FL
Cruise-In VIII Veteran
St. Jude Donor '07
I assume you are in 6th gear---Which at low speeds on any car with a 3.42 rear end will be jerky--easiest fix would be to downshift to 5th and get the RPM's up--but I realize you are going downhill so not really a good remendy--
The combination of the Varrram and the LT's also add to the issue-- Varrarams change the MAF signal and require special tuning to get your fuel trims at "0" or slightly negative-The LT's change how your 02's work--because the 02 bungs are further aft than the stock manifolds ---you get erroneous 02 readings--Your closed loop (PT) fueling becomes richer--more like 14.2 instead of 14.68--again correctable with tuning
Check to see if when they1st tuned your car if they messed with the "DFCO" settings---deceleration fuel cut-off--Someimes on a hd /cam install tuners will to eliminate dieing wen coming to a stop
Stock setting should not enable it OVER 25 MPH
ALSO you can make an adjustmnet to your "throttle follower " table--
This table either speeds up or slows down the speed of the throttle when closing it--slowing it down would make it on longer when lifting off the gas going downhill--maybe just enough to overcome the jerking
The combination of the Varrram and the LT's also add to the issue-- Varrarams change the MAF signal and require special tuning to get your fuel trims at "0" or slightly negative-The LT's change how your 02's work--because the 02 bungs are further aft than the stock manifolds ---you get erroneous 02 readings--Your closed loop (PT) fueling becomes richer--more like 14.2 instead of 14.68--again correctable with tuning
Check to see if when they1st tuned your car if they messed with the "DFCO" settings---deceleration fuel cut-off--Someimes on a hd /cam install tuners will to eliminate dieing wen coming to a stop
Stock setting should not enable it OVER 25 MPH
ALSO you can make an adjustmnet to your "throttle follower " table--
This table either speeds up or slows down the speed of the throttle when closing it--slowing it down would make it on longer when lifting off the gas going downhill--maybe just enough to overcome the jerking
Thread Starter
Advanced
Joined: Sep 2002
Posts: 91
Likes: 0
From: Oyen Alberta
I assume you are in 6th gear---Which at low speeds on any car with a 3.42 rear end will be jerky--easiest fix would be to downshift to 5th and get the RPM's up--but I realize you are going downhill so not really a good remendy--
The combination of the Varrram and the LT's also add to the issue-- Varrarams change the MAF signal and require special tuning to get your fuel trims at "0" or slightly negative-The LT's change how your 02's work--because the 02 bungs are further aft than the stock manifolds ---you get erroneous 02 readings--Your closed loop (PT) fueling becomes richer--more like 14.2 instead of 14.68--again correctable with tuning
Check to see if when they1st tuned your car if they messed with the "DFCO" settings---deceleration fuel cut-off--Someimes on a hd /cam install tuners will to eliminate dieing wen coming to a stop
Stock setting should not enable it OVER 25 MPH
ALSO you can make an adjustmnet to your "throttle follower " table--
This table either speeds up or slows down the speed of the throttle when closing it--slowing it down would make it on longer when lifting off the gas going downhill--maybe just enough to overcome the jerking
The combination of the Varrram and the LT's also add to the issue-- Varrarams change the MAF signal and require special tuning to get your fuel trims at "0" or slightly negative-The LT's change how your 02's work--because the 02 bungs are further aft than the stock manifolds ---you get erroneous 02 readings--Your closed loop (PT) fueling becomes richer--more like 14.2 instead of 14.68--again correctable with tuning
Check to see if when they1st tuned your car if they messed with the "DFCO" settings---deceleration fuel cut-off--Someimes on a hd /cam install tuners will to eliminate dieing wen coming to a stop
Stock setting should not enable it OVER 25 MPH
ALSO you can make an adjustmnet to your "throttle follower " table--
This table either speeds up or slows down the speed of the throttle when closing it--slowing it down would make it on longer when lifting off the gas going downhill--maybe just enough to overcome the jerking
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
YES the throttle follower table can only be found using HP or EFILIVE as far as I know----Another table that helps this same situation is called the "desired aiflow " table--both for in gear and P/N--it's called this in EFILVE but HP calls it something else but similar andis the same table---it is ECT based---ADDING a % will make it hang on longer as well--subtracting would make it idle down faster or try to die--
