Still cant figure out idle tuning
07-14-2005, 08:51 AM
#1
Still cant figure out idle tuning Hi all, Im still having all sorts of idle tuning issues...
On a cold start (~75º), the motor bogs down for a few seconds until it finds idle. The desired idle airflow goes up around 5 LB/min, while dynamic airflow is only around 2 LB/min. The IAC counts max out at 310, and STIT goes to like +3 LB/min. After the car starts to warm up, everything comes back down. After driving for a while, the IAC count at idle goes to ~35, and my LTIT is between 0 and -.10. My desired airflow then goes down to about .80 LB/min while dynamic at idle is still ~1.30 Lb/min. Ive tried to follow the guides, even WS6FirebirdTA00's new idle howto, but it dosnt seem to be helping. Im obviously not doing something right.
My tables look like this:
RAF:
22 22 22 22 20 19 17 15 12.5 11 9 8.75 8.75 8.75 8.75 8.75
IAC effective area:
0 0 0 0 0 0 0 0 0 0 1 8 12 18 25 32 39 46 54 61 68 76 86 95 101 107 114 121 125 131 137 143 147 154 157 165 169 172 176 179 183 185 191 194 198 203 209 214 219 224 231 236 242 249 256 264 276 289 300 305 310
IAC Park vs IAT:
42 40 38 35 32 28 25 25 25 25
Idle speed:
1150 1150 1150 1150 1100 1100 1050 1000 950 900 850 850 850 850 850 850
Where am I waaaaaaaaay off?
Thanks,
-Tony
On a cold start (~75º), the motor bogs down for a few seconds until it finds idle. The desired idle airflow goes up around 5 LB/min, while dynamic airflow is only around 2 LB/min. The IAC counts max out at 310, and STIT goes to like +3 LB/min. After the car starts to warm up, everything comes back down. After driving for a while, the IAC count at idle goes to ~35, and my LTIT is between 0 and -.10. My desired airflow then goes down to about .80 LB/min while dynamic at idle is still ~1.30 Lb/min. Ive tried to follow the guides, even WS6FirebirdTA00's new idle howto, but it dosnt seem to be helping. Im obviously not doing something right.
My tables look like this:
RAF:
22 22 22 22 20 19 17 15 12.5 11 9 8.75 8.75 8.75 8.75 8.75
IAC effective area:
0 0 0 0 0 0 0 0 0 0 1 8 12 18 25 32 39 46 54 61 68 76 86 95 101 107 114 121 125 131 137 143 147 154 157 165 169 172 176 179 183 185 191 194 198 203 209 214 219 224 231 236 242 249 256 264 276 289 300 305 310
IAC Park vs IAT:
42 40 38 35 32 28 25 25 25 25
Idle speed:
1150 1150 1150 1150 1100 1100 1050 1000 950 900 850 850 850 850 850 850
Where am I waaaaaaaaay off?
Thanks,
-Tony
07-14-2005, 07:53 PM
#2
send me your logs and tune for that log and ill do the stuff for you and explain what i did, redhardsupra is gonna host the new one i have that will explain everything a lot better. ive got my car to start now without bogging. send me a full list of specs and ill send it to you and also post up here for eveyone else to see what i did, and you can let us know what works, may take a few times but im almost positive i can work it out for you 
07-14-2005, 08:52 PM
#4
Actually, Ill have to wait till the morning, but I think I may have fixed my problem. The IAC hole in my throttle body epoxy was on ~1/4 inch, which was limiting the airflow. I drilled it out to about a half inch. Warm starts have sounded nice and healthy, and hopefully tomorrow morning's startup will be the same. Ill try following your instructions once again now that my IAC counts shouldnt max out. Thanks for the help!
07-14-2005, 09:04 PM
#5
if they are there is an easy fix, go to your friction airflow, under the idle airflow tab and lower all values from 20*c and up to 3.5 g/sec. you can also go to the start up spark correction multiplier table and put all those values to 0.55 that are at 1.0. but you were on the right track anyway. waht happens is on start up the iac hole is too tiny to flow the demanded air through it causing the rpms to fluctuate, which is why you want the iac set up right so they wont fluctuate when giving the car gas or letting out and so on and so forth. get a log though of start up tomorrow and send that and the tune to me and ill give you anythig else you need in it. i dont have the second half of the write up posted yet but it covers all this stuff. i was determined to get this all set up right without taking the epoxy out and it seems to be working, *knocking on wood*.
how much did you drill the hole out. im thinking in winter i might be at or above my airflow limit and may have to do this if the coolant temps get around or below freezing, we will see
how much did you drill the hole out. im thinking in winter i might be at or above my airflow limit and may have to do this if the coolant temps get around or below freezing, we will see
07-14-2005, 09:32 PM
#7
ive got my car to have 15-17* of timing on cold start and that seems to be a good point, humpinss are you talking about 18* at cold start or warm idle?
guits boy, i did a lot from cold start, shut her down and restarted 5* later, start up was a lot better becasue the airflow demand started to go down and the car could recover itself by the time the rpms came down from initial start. so to me it seems with a bigger hole your cold start problem shouldnt be there as bad, may need to adjust a little bit of the airflwo though still
guits boy, i did a lot from cold start, shut her down and restarted 5* later, start up was a lot better becasue the airflow demand started to go down and the car could recover itself by the time the rpms came down from initial start. so to me it seems with a bigger hole your cold start problem shouldnt be there as bad, may need to adjust a little bit of the airflwo though still
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07-15-2005, 08:05 AM
#10
Problems are gone! Its was simply the hole choking the IAC. With all the tables put back to stock except RAF, she fired right up with authority. After I get my MAF table back inline (should be done soon) Ill dial in the RAF, but right now its running so well I dont even want to change it. Thanks for all the help!
07-15-2005, 09:48 AM
#12
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Originally Posted by GuitsBoy
Problems are gone! Its was simply the hole choking the IAC. With all the tables put back to stock except RAF, she fired right up with authority. After I get my MAF table back inline (should be done soon) Ill dial in the RAF, but right now its running so well I dont even want to change it. Thanks for all the help!
07-15-2005, 10:51 AM
#15
I have a stock 1/8 hole in the throttlebody blade. As for the IAC hole, I enlarged it to about 3/8" and then did some blending with the dremel. Its no longer a regular shaped hole, but it probably has about the same volume as a 1/2" hole would. This is probably overkill. Enlarging to 3/8" was probably plenty, but i figured since the IAC plunger bore itself seems to be about 1/2 - 5/8, I might as well go as big as I could. So far so good.
07-15-2005, 11:05 AM
#17
ive got the copper in mine and didnt wanna screw it up, hence finding a way around it. thats why i wanted to knwo if it was copper so i could find an easy way to take care of it lol. thanks for the info, makes me feel better knowing it really is the hole size and not so much the tune lol
07-15-2005, 01:35 PM
#19
Is there a field to change base (IAT closed) area? While my TB hole has not been enlarged, I do have some blowby assumingly from the TB blade seal, even though i was careful there. I dont think theres a base, so maybe I should just subtract from the whole IAC pos vs. effective area table?
07-15-2005, 01:48 PM
#20
i dont know if i get what you are saying really. but what it sounds like is with the iac closed all the way the airflow that you get, that is where the effective area table is zeroed out. that write up i have covers that, i dont know how good i explained myself so if u cant get it to work email me the stuff and ill show you lol
