Car tries to die at start up
11-19-2007, 11:56 PM
#1
TECH Fanatic
Thread Starter
iTrader: (23)
Join Date: Sep 2005
Location: Joplin,MO
Posts: 1,132
Likes: 0
Received 0 Likes
on
0 Posts
Car tries to die at start up I'm not sure if I picked the right area to post this in.
After I did the Cam install my car tries to die at start up. It tries to idle at 300-500 RPM then after a few seconds it goes up to 900 RPM like it's suppose to.
I haven't drilled out the air hole in the throttle body because I have heard that it can mess up the tune.
Any ideas?
Thanks.
After I did the Cam install my car tries to die at start up. It tries to idle at 300-500 RPM then after a few seconds it goes up to 900 RPM like it's suppose to.
I haven't drilled out the air hole in the throttle body because I have heard that it can mess up the tune.
Any ideas?
Thanks.
11-20-2007, 12:45 AM
#2
leave the key in the on position for a few seconds before you try to start it? usually (after a pcm flash) I let the fuel pump prime up first and it works fine but if I don't then it idles rough as **** and tries to die.
11-24-2007, 04:38 AM
#7
sure we can help you with your car... provided you have some tuning software. Yo DO have some software right, I mean you are asking for help here in the tuning forum for what is clearly a basic tuning issue... You can see how it would be hard to have your cold startups nailed on a tune on some dyno after all, how many cold start opportunities can you have on the dyno to test this? Yeah, none.
Assuming so (that you have some software), you need to increase the startup airflow @ whatever temp you are having weak starts. Also, turn the camshaft delay for decay to some higher number like 12-16 or something. You can use the friction air or startup air table, they both just add to one another anyway.
Assuming so (that you have some software), you need to increase the startup airflow @ whatever temp you are having weak starts. Also, turn the camshaft delay for decay to some higher number like 12-16 or something. You can use the friction air or startup air table, they both just add to one another anyway.
Trending Topics
11-26-2007, 10:53 PM
#12
9 Second Club
iTrader: (7)
Join Date: May 2005
Location: Cabot, AR
Posts: 3,126
Likes: 0
Received 0 Likes
on
0 Posts
Startup friction airflow is the table to remedy the start stumble and die syndrome. It adds airflow only on startup, and decays the air back out smoothly over a short period of time.
11-27-2007, 09:31 AM
#13
Ok, sooooo, you want ideas, but you dont want ideas? Theres only about a 1/2 dozen people on here that will even take a stab at it. My feeling is, and the guys on the HPT forum will tell you the same, if ya want help, ya gotta post your tune and preferably your tune and a run log.
11-27-2007, 03:07 PM
#15
TECH Fanatic
Thread Starter
iTrader: (23)
Join Date: Sep 2005
Location: Joplin,MO
Posts: 1,132
Likes: 0
Received 0 Likes
on
0 Posts
I'm just saying I've had enough problems and I don't want any more. If you guys know what your doing then hell yeah I need your help, but also there are a lot of people out there than just think they know what there doing but really don't. Just because you have the tuning program doesnt mean that you know what your doing, you know what I mean?
11-27-2007, 04:42 PM
#16
yeah it hit me the wrong way I guess, no harm 
don't take a file, copy the text of what I (and others) told you to change, get your buddy's setup and read your file. Change what you wrote down from here and see that it fixes it. If it's still weak, add more air, if it revs up too high, take some away. Do it yourself and see the effect. Also know that there is a delay and a decay for that airflow adder. The delay is how long it holds at the value you have placed in the table before the decay begins, which is it tapering off. A less aggressive decay will bring it down slower.
DIY and see it for yourself.
don't take a file, copy the text of what I (and others) told you to change, get your buddy's setup and read your file. Change what you wrote down from here and see that it fixes it. If it's still weak, add more air, if it revs up too high, take some away. Do it yourself and see the effect. Also know that there is a delay and a decay for that airflow adder. The delay is how long it holds at the value you have placed in the table before the decay begins, which is it tapering off. A less aggressive decay will bring it down slower.
DIY and see it for yourself.
11-27-2007, 06:48 PM
#17
TECH Fanatic
Thread Starter
iTrader: (23)
Join Date: Sep 2005
Location: Joplin,MO
Posts: 1,132
Likes: 0
Received 0 Likes
on
0 Posts
Thanks a lot!
also a inportant bit of info I forgot to add. The car runs really rich. It throws flames out when I shift and you can smell the extra gas in the exhaust.
I'll get one of my dyno sheets up on here also. I have a couple of start up and driving files that I will try and get from my friend so I can get them up on here so you can see for yourself what the car is doing.
also a inportant bit of info I forgot to add. The car runs really rich. It throws flames out when I shift and you can smell the extra gas in the exhaust.
I'll get one of my dyno sheets up on here also. I have a couple of start up and driving files that I will try and get from my friend so I can get them up on here so you can see for yourself what the car is doing.
11-27-2007, 09:41 PM
#19
TECH Fanatic
Join Date: Feb 2004
Location: Lexington, KY
Posts: 1,259
Likes: 0
Received 0 Likes
on
0 Posts
It needs idle/driveability tuning. Dyno tuning usually only addresses wot/pe mode for the most part. It can take some time and know how to get it dialed in for good street manners. Mine is the first one I've done and it took me a few months of nights and weekends to get it decent.