Need Help with Surging Idle
10-18-2010, 07:37 PM
#1
Need Help with Surging Idle So i am having trouble with this damn idle. when it starts the afr is between 16-17. the idle is surging like crazy. i have the ve table tuned pretty good. car has no maf and i am running 1 bar custom os. mods are: tr230/224, 111 lsa and prc 5.3 l stage 2 heads, and delphi 42 lb injectors. i have the idle rpm set at 900 rpms. car is currently in open loop. what should i be lookin at when tuning idle? i attached a tune and log.
10-18-2010, 07:49 PM
#2
Order of operations.....
start in open loop.
First get Fueling in line, part Throttle.. and Idle.. both stoic(14.7ish for gas..a little lower if you get a pump with up to 10% ethanol)
I would guess that your idle fueling is most of your problem... get it around stoic... lambda 1.0 / 14.7 / whatever you want to call it.
then get spark at idle up to par...probably 26*~28* @ Idle
also adjust Idle underspeed table to be exact opposite of the overspeed table...
should be at approximately +/- 16* by 400 rpm above or below 0
then get some Idle Airflow values for hot idle...add enough air to the RAF table to make it hang high(better than not enough and it dies)..
with engine at full temperature, fans commanded off, AC turned off... check IAC position..
should be in the 60~80 range
if its not.. get there somehow.. I prefer to drill a hole in the TB Blade until it falls in range..
others like to move the bump stop screw...but you cant go past .55 volts or you lose some idle tables(even if you are at 0% TPS)
then do a cold start and get Idle Airflow in line...add 0.50 grams per second to the whole table when thru.
once you get that... it should idle just fine
start in open loop.
First get Fueling in line, part Throttle.. and Idle.. both stoic(14.7ish for gas..a little lower if you get a pump with up to 10% ethanol)
I would guess that your idle fueling is most of your problem... get it around stoic... lambda 1.0 / 14.7 / whatever you want to call it.
then get spark at idle up to par...probably 26*~28* @ Idle
also adjust Idle underspeed table to be exact opposite of the overspeed table...
should be at approximately +/- 16* by 400 rpm above or below 0
then get some Idle Airflow values for hot idle...add enough air to the RAF table to make it hang high(better than not enough and it dies)..
with engine at full temperature, fans commanded off, AC turned off... check IAC position..
should be in the 60~80 range
if its not.. get there somehow.. I prefer to drill a hole in the TB Blade until it falls in range..
others like to move the bump stop screw...but you cant go past .55 volts or you lose some idle tables(even if you are at 0% TPS)
then do a cold start and get Idle Airflow in line...add 0.50 grams per second to the whole table when thru.
once you get that... it should idle just fine
10-19-2010, 12:44 PM
#7
So i am having trouble with this damn idle. when it starts the afr is between 16-17. the idle is surging like crazy. i have the ve table tuned pretty good. car has no maf and i am running 1 bar custom os. mods are: tr230/224, 111 lsa and prc 5.3 l stage 2 heads, and delphi 42 lb injectors. i have the idle rpm set at 900 rpms. car is currently in open loop. what should i be lookin at when tuning idle? i attached a tune and log.
There is no need to drill a hole in the TB at all for that cam. Even an MS4 cam will idle fine if the tuning is right without the hole, and its alot larger than that cam you have.
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10-19-2010, 01:10 PM
#8
Why are you running running with no maf on the 1 bar os? The idle surge can normally be taken over by changing the idle timing to a more static number. You should try this out with the RTT tool in the scanner. Just up the spark advance until the engine likes it. There is no need for that car to idle at 900 either. You could make it idle good at 800 or 850. Why do you have the car in open loop aslo? There are so many questions. Did you change the idle airflow? Throttle cracker? How about the OL EQ ratio? That will effect how much fuel is put in now since you turned closed loop off. The VE table will help some, but that is airflow. Your idle spark is all over the place. Change it to what you find is a happy medium and you will see it act better. But make sure to change more than that. You need to address the idle AFR def. But that OL table will do that.
There is no need to drill a hole in the TB at all for that cam. Even an MS4 cam will idle fine if the tuning is right without the hole, and its alot larger than that cam you have.
There is no need to drill a hole in the TB at all for that cam. Even an MS4 cam will idle fine if the tuning is right without the hole, and its alot larger than that cam you have.
RAF tables have been changed, not throttle cracker, I set ol eq ratio to 1, like the instructions stated. i remember changing the idle timing using RTT, but it did nothing for me. i will try it again.
10-19-2010, 02:34 PM
#9
Hmm. Well deleting the MAF due to that reason is really not worth it IMO. But just make sure that you have ALL the VE cells that you will be using correct. I would look again at the idle spark settings.
For a start, change the idle spark in P/N to about 25 from 400 all the way to 1200 and see how it likes that. Then flash. Then from there, use the RTT to change the idle spark more or less. That can help it some. The fueling and air are what you should have dialed in first. Normally if you put it back, it can help out as the fuel/air can now work on its own, but you wont know until you try.
For a start, change the idle spark in P/N to about 25 from 400 all the way to 1200 and see how it likes that. Then flash. Then from there, use the RTT to change the idle spark more or less. That can help it some. The fueling and air are what you should have dialed in first. Normally if you put it back, it can help out as the fuel/air can now work on its own, but you wont know until you try.
10-19-2010, 02:52 PM
#10
Hmm. Well deleting the MAF due to that reason is really not worth it IMO. But just make sure that you have ALL the VE cells that you will be using correct. I would look again at the idle spark settings.
For a start, change the idle spark in P/N to about 25 from 400 all the way to 1200 and see how it likes that. Then flash. Then from there, use the RTT to change the idle spark more or less. That can help it some. The fueling and air are what you should have dialed in first. Normally if you put it back, it can help out as the fuel/air can now work on its own, but you wont know until you try.
For a start, change the idle spark in P/N to about 25 from 400 all the way to 1200 and see how it likes that. Then flash. Then from there, use the RTT to change the idle spark more or less. That can help it some. The fueling and air are what you should have dialed in first. Normally if you put it back, it can help out as the fuel/air can now work on its own, but you wont know until you try.
10-19-2010, 02:59 PM
#11
No. We are talking about idle spark ONLY. NO other table. You have 2 tables for that. In Park and In Drive. Change both of the tables to about 25 or so and see how it turns out. All the way down and all the way to about 1200. Then turn the tables above that up some but keep them constant if you can. That is your spark advance from coastdown as well. As well as anything below like 3mph in gear. If that gives worse problems, leave them the way they were, but normally this helps out quite a bit.
10-19-2010, 08:32 PM
#12
No. We are talking about idle spark ONLY. NO other table. You have 2 tables for that. In Park and In Drive. Change both of the tables to about 25 or so and see how it turns out. All the way down and all the way to about 1200. Then turn the tables above that up some but keep them constant if you can. That is your spark advance from coastdown as well. As well as anything below like 3mph in gear. If that gives worse problems, leave them the way they were, but normally this helps out quite a bit.
10-19-2010, 08:38 PM
#13
I personally like to see all 4 tables having the same spark down low and at idle...keeps you from having any sudden changes in spark that would compromise the return from part throttle to idle.
if you have a stock TB, you shouldnt have to mess with the IAC effective area table.
I would also guess that putting the car back in closed loop, and allowing teh o2 sensors to deal with fueling, has gotten your A/F ratio back to stoic, which is a huge necessity at idle.
as I stated earlier, I thought that fueling was the primary problem for you at idle...and now the car has control of it instead of you.
10-19-2010, 09:34 PM
#14
you should change it in both the Idle spark tables and the High/Low Octane spark tables..
I personally like to see all 4 tables having the same spark down low and at idle...keeps you from having any sudden changes in spark that would compromise the return from part throttle to idle.
if you have a stock TB, you shouldnt have to mess with the IAC effective area table.
I would also guess that putting the car back in closed loop, and allowing teh o2 sensors to deal with fueling, has gotten your A/F ratio back to stoic, which is a huge necessity at idle.
as I stated earlier, I thought that fueling was the primary problem for you at idle...and now the car has control of it instead of you.
I personally like to see all 4 tables having the same spark down low and at idle...keeps you from having any sudden changes in spark that would compromise the return from part throttle to idle.
if you have a stock TB, you shouldnt have to mess with the IAC effective area table.
I would also guess that putting the car back in closed loop, and allowing teh o2 sensors to deal with fueling, has gotten your A/F ratio back to stoic, which is a huge necessity at idle.
as I stated earlier, I thought that fueling was the primary problem for you at idle...and now the car has control of it instead of you.
ok, so i did what yall suggested and changed all 4 spark tables. i attached my tune.
another question, i have been reading a lil about frictional airflow and startup airflow; should i play with those?
10-19-2010, 09:41 PM
#15
out of curiosity? is there a stock size hole in the BBK? because there should be...make one if it doesnt exist... you will be a lot more stable of an idle if you have it.
if it doesnt have a hole.. try throwing on a stock TB and see how much better idle is...
idle is all about proper airflow/fueling/and spark
you get one of them wrong and idle goes to hell
the IAC passageway on the BBK is a little different than a stock TB...you may need to play with the IAC effective area table some.. but its not going to cause your idle surging issues.. it usually is responsible more for return to idle from rolling part throttle when you come to a stop...if you have some dips when you come to a stop and you already have done a proper RAF table, then thats when you should start looking at the IAC table.
if you are having problems with startup, then you can look at Frictional and startup airflow tables...otherwise, not really a need to mess with them.
if it doesnt have a hole.. try throwing on a stock TB and see how much better idle is...
idle is all about proper airflow/fueling/and spark
you get one of them wrong and idle goes to hell
the IAC passageway on the BBK is a little different than a stock TB...you may need to play with the IAC effective area table some.. but its not going to cause your idle surging issues.. it usually is responsible more for return to idle from rolling part throttle when you come to a stop...if you have some dips when you come to a stop and you already have done a proper RAF table, then thats when you should start looking at the IAC table.
if you are having problems with startup, then you can look at Frictional and startup airflow tables...otherwise, not really a need to mess with them.
10-19-2010, 09:58 PM
#16
problem is i sold my tb, so i dont have a stock one. i am having a small dipping problem that u were talkin about, but i am not worried about that now. i will mess with that later. the car startups fine and stays good for like 10 secs and then starts surging. in this link, the op seems to be having the same problems i am. what do u suggest?
10-19-2010, 10:07 PM
#17
problem is i sold my tb, so i dont have a stock one. i am having a small dipping problem that u were talkin about, but i am not worried about that now. i will mess with that later. the car startups fine and stays good for like 10 secs and then starts surging. in this link, the op seems to be having the same problems i am. what do u suggest?
again.. to me.. it sounds like an idle airflow problem.. IAC cant keep up with the demands of the airflow needs at idle.
do you have a small hole in the BBK just like the stock TB has or is it a solid plate?
if it doesnt have a small hole, you need to add one, just like the stock TB..
stock hole is 5/32.. and I just verified it with my old TB sitting on a shelf here at home.
10-19-2010, 10:15 PM
#18
again.. to me.. it sounds like an idle airflow problem.. IAC cant keep up with the demands of the airflow needs at idle.
do you have a small hole in the BBK just like the stock TB has or is it a solid plate?
if it doesnt have a small hole, you need to add one, just like the stock TB..
stock hole is 5/32.. and I just verified it with my old TB sitting on a shelf here at home.
do you have a small hole in the BBK just like the stock TB has or is it a solid plate?
if it doesnt have a small hole, you need to add one, just like the stock TB..
stock hole is 5/32.. and I just verified it with my old TB sitting on a shelf here at home.
10-19-2010, 10:35 PM
#19
not really.. honestly, to put a stock hole in the TB blade.. should only be a 20 minute project at the most...
take off the Lid so you can get to it..a few simple tools to remove the TB...
drill a hole, put it all back together...
you can actually drill with it in the car if you put a damp rag into the TB to catch the shavings.. I do it that way all the time...
just go slow, and pull the rag out slow and steady.. be sure to wipe down well to get all the shavings out...
take off the Lid so you can get to it..a few simple tools to remove the TB...
drill a hole, put it all back together...
you can actually drill with it in the car if you put a damp rag into the TB to catch the shavings.. I do it that way all the time...
just go slow, and pull the rag out slow and steady.. be sure to wipe down well to get all the shavings out...
10-19-2010, 10:52 PM
#20
well i changed some of the injector settings that a member posted on here on an excel sheet for the 42 lb'ers. it helped. also set the iac table back to stock and then set the startup airflow delay to 70 revs. it surges for a little then settles down a lot quicker than before.