Low idle when cold?
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
Low idle when cold?
Hi guys, 1985 Corvette, quite a few modifications.
Mini ram, longtube headers, flat tappet zz409 cam, all free mods, k&n air filter, msd 8.5mm ignition wires, 58mm throttle body, stock heads.
Anyways, when I first turn it on, it is kind of weird. It idles at around 500-600 RPMs. After it warms up and goes into closed loop it idles at 700-750 ish.
The car has a tune and the AFR guage reads rich around 12-13:1 when it is cold, as it warms up and the idle increases, it reads around 14.7:1.
Has anybody ever experienced a problem like this? If I remember correctly, the idle while cold used to be around 700-750.
Thanks.
Mini ram, longtube headers, flat tappet zz409 cam, all free mods, k&n air filter, msd 8.5mm ignition wires, 58mm throttle body, stock heads.
Anyways, when I first turn it on, it is kind of weird. It idles at around 500-600 RPMs. After it warms up and goes into closed loop it idles at 700-750 ish.
The car has a tune and the AFR guage reads rich around 12-13:1 when it is cold, as it warms up and the idle increases, it reads around 14.7:1.
Has anybody ever experienced a problem like this? If I remember correctly, the idle while cold used to be around 700-750.
Thanks.
Racer
Joined: Aug 2013
Posts: 301
Likes: 0
Hi guys, 1985 Corvette, quite a few modifications.
Mini ram, longtube headers, flat tappet zz409 cam, all free mods, k&n air filter, msd 8.5mm ignition wires, 58mm throttle body, stock heads.
Anyways, when I first turn it on, it is kind of weird. It idles at around 500-600 RPMs. After it warms up and goes into closed loop it idles at 700-750 ish.
The car has a tune and the AFR guage reads rich around 12-13:1 when it is cold, as it warms up and the idle increases, it reads around 14.7:1.
Has anybody ever experienced a problem like this? If I remember correctly, the idle while cold used to be around 700-750.
Thanks.
Mini ram, longtube headers, flat tappet zz409 cam, all free mods, k&n air filter, msd 8.5mm ignition wires, 58mm throttle body, stock heads.
Anyways, when I first turn it on, it is kind of weird. It idles at around 500-600 RPMs. After it warms up and goes into closed loop it idles at 700-750 ish.
The car has a tune and the AFR guage reads rich around 12-13:1 when it is cold, as it warms up and the idle increases, it reads around 14.7:1.
Has anybody ever experienced a problem like this? If I remember correctly, the idle while cold used to be around 700-750.
Thanks.
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
It should be. Or at least it was working, I was getting different step counts. But I did notice at one point when I was recording step counts, I had unplugged the IAC and it was still reading different step counts.
I guess that its possible that it could just be what the computer wants it to do but, it may not be functioning?
I'm going to investigate it a little more when I get home.
I guess that its possible that it could just be what the computer wants it to do but, it may not be functioning?
I'm going to investigate it a little more when I get home.
Racer
Joined: Aug 2013
Posts: 301
Likes: 0
It should be. Or at least it was working, I was getting different step counts. But I did notice at one point when I was recording step counts, I had unplugged the IAC and it was still reading different step counts.
I guess that its possible that it could just be what the computer wants it to do but, it may not be functioning?
I'm going to investigate it a little more when I get home.
I guess that its possible that it could just be what the computer wants it to do but, it may not be functioning?
I'm going to investigate it a little more when I get home.
Last edited by nobodycls; Dec 21, 2013 at 12:55 PM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I think your CTS (Coolant Temperature Sensor) has a problem. Either the sensor itself, the connector pins could be corroded or the wiring could have a problem.
This is the CTS on the front of the intake manifold under the throttle body.
If the ECM thinks the coolant is cold it will raise the idle. If it thinks the coolant is hot (which appears to be your case) it will lower the idle. The best way to find out is with a scanner, either standalone or laptop software.
This is the CTS on the front of the intake manifold under the throttle body.
If the ECM thinks the coolant is cold it will raise the idle. If it thinks the coolant is hot (which appears to be your case) it will lower the idle. The best way to find out is with a scanner, either standalone or laptop software.
