Need Help with Surging Idle
10-20-2010, 08:42 AM
#21
If you wanted it to help itself with the tuning, leaving the maf in was probably your better option really. You have to watch out with setting the airflow tables too high, or it will hang for a little bit, and also it will idle higher, or erratic. The same thing with the friction and startup airflow.
A few of your problems may be related to the fueling you have. When it is in open loop at the beginning if your key cycle, it dumps more fuel in, leaving a cushion for it to run on. Then closed loop comes in and ruins the party. You will need to adjust your closed loop fueling now at idle. When you were SD/VE tuning....did not you do idle first? Alot of books/write ups assume either your idle is fine, or that you have already addressed it.
A few of your problems may be related to the fueling you have. When it is in open loop at the beginning if your key cycle, it dumps more fuel in, leaving a cushion for it to run on. Then closed loop comes in and ruins the party. You will need to adjust your closed loop fueling now at idle. When you were SD/VE tuning....did not you do idle first? Alot of books/write ups assume either your idle is fine, or that you have already addressed it.
10-20-2010, 10:18 AM
#22
If you wanted it to help itself with the tuning, leaving the maf in was probably your better option really. You have to watch out with setting the airflow tables too high, or it will hang for a little bit, and also it will idle higher, or erratic. The same thing with the friction and startup airflow.
A few of your problems may be related to the fueling you have. When it is in open loop at the beginning if your key cycle, it dumps more fuel in, leaving a cushion for it to run on. Then closed loop comes in and ruins the party. You will need to adjust your closed loop fueling now at idle. When you were SD/VE tuning....did not you do idle first? Alot of books/write ups assume either your idle is fine, or that you have already addressed it.
A few of your problems may be related to the fueling you have. When it is in open loop at the beginning if your key cycle, it dumps more fuel in, leaving a cushion for it to run on. Then closed loop comes in and ruins the party. You will need to adjust your closed loop fueling now at idle. When you were SD/VE tuning....did not you do idle first? Alot of books/write ups assume either your idle is fine, or that you have already addressed it.
10-20-2010, 10:39 AM
#23
your VE table takes care of all fueling in your case...Idle, Part throttle, and WOT
you were probably told to take care of fueling first, then idle...which means take care of VE first and then the Idle spark and airflow tables after that.
honestly its an all in one kind of thing...
you cant just focus on one part at first.. you have to do all 3 at once to get the car stable enough to actually tune on it.. after its stable you can break it down to the individual parts.
the MAF isnt always the best answer...but it definitely acts like a sponge and soaks up a lot of the errors involved in tuning.
its certainly easier to tune a car that is 100% MAF vs ones like our Fbody's that use a blend of VE and MAF normally.
being in SD its definitely easier than trying to get both VE and MAF to jive together correctly.
if the car starts up fine, then you really dont need to mess with frictional or startup airflow tables...and I'm not talking about idle swings 10 seconds after startup... I'm talking about the initial turn of the key to get the engine to fire up.
you were probably told to take care of fueling first, then idle...which means take care of VE first and then the Idle spark and airflow tables after that.
honestly its an all in one kind of thing...
you cant just focus on one part at first.. you have to do all 3 at once to get the car stable enough to actually tune on it.. after its stable you can break it down to the individual parts.
the MAF isnt always the best answer...but it definitely acts like a sponge and soaks up a lot of the errors involved in tuning.
its certainly easier to tune a car that is 100% MAF vs ones like our Fbody's that use a blend of VE and MAF normally.
being in SD its definitely easier than trying to get both VE and MAF to jive together correctly.
if the car starts up fine, then you really dont need to mess with frictional or startup airflow tables...and I'm not talking about idle swings 10 seconds after startup... I'm talking about the initial turn of the key to get the engine to fire up.
10-20-2010, 10:56 AM
#24
Well normally I would use the MAf table for some. But most of it should be in your VE table. In closed loop that is. In the open loop, it is still the OL table.
Use the same histogram that you used for the VE tuning, just let it idle and see what the cells show. Do not let it idle too much though without driving it some in between to let the O2s breathe some fresh air. Then go back at it.
To be honest, I would not have stepped away from the MAF.
Use the same histogram that you used for the VE tuning, just let it idle and see what the cells show. Do not let it idle too much though without driving it some in between to let the O2s breathe some fresh air. Then go back at it.
To be honest, I would not have stepped away from the MAF.
10-21-2010, 09:02 AM
#25
so i have been seeing a lil dipping of the rpm when i pull up to a light, i remember u saying that might be from the iac table. I was reading that some ppl copied the values and moved a spot to the right and pasted the values and replace the 1 with a 0. Is this correct?
10-21-2010, 09:10 AM
#26
Sometimes the dip in the rpm is the transition from one spark table to another. Sometimes it is airflow. Sometimes it is the throttle cracker table. Sometimes it is the base running idle airflow table. The best advice I can give is to take a look at the scans you have and see what it is doing then make small changes to one of the tables and see what happens. After you have done it for a while, you will realize what you need to change and where.
10-21-2010, 05:37 PM
#27
Its not the throttle Cracker...
Throttle Cracker is for airflow when the car is in "coast" mode... cruising down the road.. let of the gas.. clutch still engaged...
typically it decays to 0 when you push in the clutch.. in an automatic its usually responsible for any surging and bucking you get while coasting.. too much and it bucks..not enough and it dies...
but it can be spark, it can be fuel , and it can be IAC table...
you cant just blindly move over the IAC... your desired airflow and dynamic airflow should closely match during deceleration of rpm's... its not an eassy tassk to get them to line up...
if you had a stock throttle body, you wouldnt have to mess with that table much.. its pretty close... but with your 80mm BBK its gonna need some adjustment. I couldnt tell you how much...
Throttle Cracker is for airflow when the car is in "coast" mode... cruising down the road.. let of the gas.. clutch still engaged...
typically it decays to 0 when you push in the clutch.. in an automatic its usually responsible for any surging and bucking you get while coasting.. too much and it bucks..not enough and it dies...
but it can be spark, it can be fuel , and it can be IAC table...
you cant just blindly move over the IAC... your desired airflow and dynamic airflow should closely match during deceleration of rpm's... its not an eassy tassk to get them to line up...
if you had a stock throttle body, you wouldnt have to mess with that table much.. its pretty close... but with your 80mm BBK its gonna need some adjustment. I couldnt tell you how much...
