Help with cold start surging
03-02-2005, 12:10 PM
#1
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Help with cold start surging Ok...Please bare with me here. I am new to this tuning thing. I have HP Tuners. Mods in sig. I am having a problem getting my car to not surge on cold startup. It idles fine but surges badly untill it is completely warmed up. It dies all the time while cold. Especially in reverse. I have done many searches and tried many things but I can't get it right. My main problem is that I have had so many people try and tune my car that it is all out of wack. The first people to tune it didn't have a clue what was going on. I do not have the stock tune either. Can someone walk me through this? What I need to log and watch out for? How to take my logged information and use it to correct my tune? What tables and parameters to change? I would greatly appreciate it. So many options and so much reading that my head hurts. Be easy on the tuning newbie.
03-02-2005, 04:48 PM
#2
I have seen a lot of posts on how to address this, and I've tried most of them with limited success. The only sure-fire solution I've found is to just sit there and pedal it until the PCM goes closed loop at about 100 *F. Even though not fully warmed up, it should be working a lot better.
03-03-2005, 06:45 AM
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Originally Posted by Blacker
The biggest help for my car was adjusting the base timing to 21* for 400-1200 rpm. I also changed the IAC Tables and that helped as well.
I have gotten it a little better but still nothing really "driveable" IMO.
Also, what and how am I to adjust in the IAC table.
Thanks a lot guys. I really appreciate all the help.
03-03-2005, 07:04 AM
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Originally Posted by Blacker
The biggest help for my car was adjusting the base timing to 21* for 400-1200 rpm. I also changed the IAC Tables and that helped as well.
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03-03-2005, 09:44 AM
#8
I have the Base Spark in Park and Drive set to 21*. This is for columns 400-1200 and rows 0.08-0.32gm/cyl.
Idle Park Position:
34.50 34.40 34.50 34.50 28.50 21 21 21 21 21
Idle Air:
22 22 22 22 18.00 15.00 10.95 9.45 9.45 9.45
22 22 22 22 16.50 15.00 12.00 9.60 9.60 9.75
High Octane Table:
-2* for 400-1000 rpm and 0.08-0.32gm/cyl
I also have the F/A Multilplier Table adjusted as well. I used jimmyblue's table. Here is the link:
https://ls1tech.com/forums/showthrea...ht=F%2FA+Table
I hope this helps
Idle Park Position:
34.50 34.40 34.50 34.50 28.50 21 21 21 21 21
Idle Air:
22 22 22 22 18.00 15.00 10.95 9.45 9.45 9.45
22 22 22 22 16.50 15.00 12.00 9.60 9.60 9.75
High Octane Table:
-2* for 400-1000 rpm and 0.08-0.32gm/cyl
I also have the F/A Multilplier Table adjusted as well. I used jimmyblue's table. Here is the link:
https://ls1tech.com/forums/showthrea...ht=F%2FA+Table
I hope this helps
03-03-2005, 11:40 AM
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OK...what you gave me helped a lot. When I fired it up it we straight to an idle. Hardly any surging at all. When I went to back out it surged but not as bad as it used to. The car was not fully warmed up. I would like to get rid of this sugring if possible. When I slowed down it surged as well. When it warmed up this surging went away. Any idea who to fix this? I am also getting a cruise control effect at about 1200 RMP while slowing down. The biggest thing I notice was that even fully warmed up, if I give it and gas and then let off abruptly the car surges down to about 500 RPM (almost dies) then climbes back up to about 1400 RPM. Then it hangs there and slowly comes back down to idle. Any ideas? Sorry for all the questions.
03-03-2005, 12:15 PM
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Will this help my dipping problem?
https://ls1tech.com/forums/pcm-diagnostics-tuning/177230-stop-drilling-those-tbs-fix-stalling-without-computer-tuning.html
https://ls1tech.com/forums/pcm-diagnostics-tuning/177230-stop-drilling-those-tbs-fix-stalling-without-computer-tuning.html
03-03-2005, 01:12 PM
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The main problem was with "you know who" tuning it. After I put it back to stock and made a few changes everything was cool. It was just too hard to start with a tune that was so messed up. I still have cruise and dipping though.
03-03-2005, 01:13 PM
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Originally Posted by Black02SS
Last time I checked, your IAC count was fine.
03-03-2005, 01:26 PM
#18
Originally Posted by dheck
I checked it today and it was around 180 and after warming up it was around 80. What is the easiest way to fix this?
Originally posted by Another_User
Stop drilling those TBs, fix stalling without computer tuning...
I was determined to fix my stalling without computer tuning or drilling, and after scouring many threads (too many) I pieced together a solution to idle problems after a cam install. This should probably NOT be used to raise your idle above the target idle speed. What I am posting below is what I have done on my 98 LS1 M6 with a Hotcam, other PCMs may (but probably won't) react differently.
The issue is that your vehicle becomes dependant on your IAC to maintain enough idle speed for your vehicle to run after you install a cam. Why? I have no idea...less vacuum at idle I guess. Since your IAC is working so hard to keep you idling, sometimes your idle will dip based on computer variables that are far too complicated for me to care about when my car won't idle right. Drilling the throttle body takes up some of the slack for the IAC and prevents the idle from dipping so much. Overdrilling causes excessive idle speed. But drilling is a sloppy way to adjust something that can be done with the set screw on the throttle body.
Instead of drilling use the set screw on your throttle body, and here is how:
1) Hookup Autotap or your diagnostic tool of choice. You will want to monitor your IAC, Idle Speed (and desired idle speed if you don't know it), and your Throttle Position.
2) With the key in the ON position, adjust your tb set screw until your Throttle Position is 2-3%. You can do this all at once, or gradually in 1% increments if you like. (I started with +3% and ended up adding another +1%).
3) Turn your key to the OFF position.
4) Unplug your Throttle Position sensor.
5) Turn your key to the ON position for a few seconds, and then OFF again.
6) Plug in the TPS (don't know why nobody caught me forgetting that step) and then turn your key to the ON position and restart Autotap. Your Throttle Position will now be reset to 0 degrees (or really close like 0.4%, the point is it is now reset).
7) Start your engine. Autotap is unable to pull IAC counts from my computer, but you can watch the Idle Air Control Airflow in grams/sec. A stock vehicle should show about 20 grams/sec, and that should probably be your target. I overdid it a little myself with the extra 1% to reduce the amount of control the IAC valve has over my idle. My grams/sec is between 5-10.
I wish I had measured the IAC airflow before the change, but I just wanted to get the thing to idle better. You will probably see much much more than 20 grams/sec if you Autotap it before the adjustment.
Basically the point is that you CAN adjust your throttle body with the set screw withough messing up your Throttle Position reading. WOT will still be between 99-100% (perfectly normal). And you will now have an idle that doesn't go too low. If any of you guys have anything to add to this, please do...or if I have made some error in doing this.
Stop drilling those TBs, fix stalling without computer tuning...
I was determined to fix my stalling without computer tuning or drilling, and after scouring many threads (too many) I pieced together a solution to idle problems after a cam install. This should probably NOT be used to raise your idle above the target idle speed. What I am posting below is what I have done on my 98 LS1 M6 with a Hotcam, other PCMs may (but probably won't) react differently.
The issue is that your vehicle becomes dependant on your IAC to maintain enough idle speed for your vehicle to run after you install a cam. Why? I have no idea...less vacuum at idle I guess. Since your IAC is working so hard to keep you idling, sometimes your idle will dip based on computer variables that are far too complicated for me to care about when my car won't idle right. Drilling the throttle body takes up some of the slack for the IAC and prevents the idle from dipping so much. Overdrilling causes excessive idle speed. But drilling is a sloppy way to adjust something that can be done with the set screw on the throttle body.
Instead of drilling use the set screw on your throttle body, and here is how:
1) Hookup Autotap or your diagnostic tool of choice. You will want to monitor your IAC, Idle Speed (and desired idle speed if you don't know it), and your Throttle Position.
2) With the key in the ON position, adjust your tb set screw until your Throttle Position is 2-3%. You can do this all at once, or gradually in 1% increments if you like. (I started with +3% and ended up adding another +1%).
3) Turn your key to the OFF position.
4) Unplug your Throttle Position sensor.
5) Turn your key to the ON position for a few seconds, and then OFF again.
6) Plug in the TPS (don't know why nobody caught me forgetting that step) and then turn your key to the ON position and restart Autotap. Your Throttle Position will now be reset to 0 degrees (or really close like 0.4%, the point is it is now reset).
7) Start your engine. Autotap is unable to pull IAC counts from my computer, but you can watch the Idle Air Control Airflow in grams/sec. A stock vehicle should show about 20 grams/sec, and that should probably be your target. I overdid it a little myself with the extra 1% to reduce the amount of control the IAC valve has over my idle. My grams/sec is between 5-10.
I wish I had measured the IAC airflow before the change, but I just wanted to get the thing to idle better. You will probably see much much more than 20 grams/sec if you Autotap it before the adjustment.
Basically the point is that you CAN adjust your throttle body with the set screw withough messing up your Throttle Position reading. WOT will still be between 99-100% (perfectly normal). And you will now have an idle that doesn't go too low. If any of you guys have anything to add to this, please do...or if I have made some error in doing this.