Closed loop on CFI
Thread Starter
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
I do know in one of my discussion with Gordon Killebrew....he mentioned that GM realized that when the O2 was so far from the engine that GM tried to keep the O2 hot by the stove shielding around the catalytic and insulation that they put around the O2. Which is why they moved the O2's up to the engine on the left bank in the later years....as I was told...if I remember correctly.
I have to agree......even though your heated O2 may show CLOSED LOOP.....IF you still ahve a high idle ....I would be more concerned IF the COOLANT TEMP SENSOR is correct. and what my voltage at the MAP sensor shows on the scanner.
Not knowing anything about the history of your throttle bodies and intake gaskets...and if for some ODD reason this high idle just started....I would have to consider throttle bodies being worn out.
I knwo I might be talking out my backside....but I deal with the Cross-Fire cars quite often and NOT that I am a leading authority on them...I just know what I have encountered and when I get them in with problems....and where I check 'things' immediately and stop when I usually find a problem that will inhibit me making any improvements until the problems I find right away are repaired.
DUB
I have to agree......even though your heated O2 may show CLOSED LOOP.....IF you still ahve a high idle ....I would be more concerned IF the COOLANT TEMP SENSOR is correct. and what my voltage at the MAP sensor shows on the scanner.
Not knowing anything about the history of your throttle bodies and intake gaskets...and if for some ODD reason this high idle just started....I would have to consider throttle bodies being worn out.
I knwo I might be talking out my backside....but I deal with the Cross-Fire cars quite often and NOT that I am a leading authority on them...I just know what I have encountered and when I get them in with problems....and where I check 'things' immediately and stop when I usually find a problem that will inhibit me making any improvements until the problems I find right away are repaired.
DUB
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
I would agree DUB, high idle isn't a simple cause of open loop vs closed loop. Something else is likely going on.
I'm surprised you guys fell for that 390* number considering the souce. The sensor element has to be much higher than that, like 600*F or more to work properly. He was close, just off by almost the use of *F vs *C.
You NEVER put a O2 sensor bung in the bottom of a pipe either.
I'm surprised you guys fell for that 390* number considering the souce. The sensor element has to be much higher than that, like 600*F or more to work properly. He was close, just off by almost the use of *F vs *C.
You NEVER put a O2 sensor bung in the bottom of a pipe either.
Last edited by lionelhutz; Dec 9, 2015 at 09:19 PM.
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
My first thought would be to check the IAC valve. It could be stuck letting excessive air into the throttle body. Also, if that doesn't work have a tuner look at your tune. There are several spark and fuel tables that add/subtract fuel/spark depending on the environment. There is also a table that controls the IAC valve. These need to be looked at when making engine/exhaust modifications.
Check the IAC motor to see what position it's in. Honestly, I don't know what it looks like on the CFI. But I relate everything to my LS motor, I know it quite abit better. I can just easily pull out the IAC motor out of the throttle body and measure the position that the valve is in, both when the coolant is cold and then after the engine warms up. If it doesn't change positions, there is your problem. It could be as simple as replacing the IAC motor.
Le Mans Master
Joined: Jul 2000
Posts: 6,663
Likes: 162
From: columbia city in
I would try this program to tell me if you are in closed not loop or not.http://winaldl.joby.se/ changing the o2 sensor to a heated one is what they did years ago.http://crossfireinjection.net/faqs.htm#ninth question check out no 9
Last edited by terry82; Dec 10, 2015 at 05:55 PM.
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
htown81vette - if you want an easy way to check the IAC then adjust the idle screw in and out when running. Alternatively, you could even use something like a feeler gauge to hold the throttle blades open just a bit more than normal. If the IAC doesn't re-adjust back to the same idle rpm then it's not working.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
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From: Las Vegas - Just stop perpetuating myths please.
If u have a scanner then look at the long term BLM and short term integrator values. For open loop u will see 128 as the default when the ECM runs on the fueling maps. If car is all warmed up and at idle and u see 128 on the fuel trim values your still in Open Loop.
I dont know the closed loop criteria for your car (and dont care to search for it) but usually there are several criteria than need to be met for closed loop operation to begin. And i dont think O2 sensor value is even one of them.
Hope this helps save u new O2 sensors. But then again something most owners dont realize is the O2 sensor is normal wear item and should be replaced 'bout the same time as the brakes or tires (unless u smoked them up
).
I dont know the closed loop criteria for your car (and dont care to search for it) but usually there are several criteria than need to be met for closed loop operation to begin. And i dont think O2 sensor value is even one of them.
Hope this helps save u new O2 sensors. But then again something most owners dont realize is the O2 sensor is normal wear item and should be replaced 'bout the same time as the brakes or tires (unless u smoked them up
).
