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Car only goes into closed loop when I give it any kind of throttle?

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Old Oct 28, 2013 | 04:12 AM
  #1  
IROCThe5.7L's Avatar
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Car: 1988 IROC-Z
Engine: 427 SBC
Transmission: ProBuilt 700R4
Axle/Gears: Moser 12 Bolt / 3.73 TrueTrac
Car only goes into closed loop when I give it any kind of throttle?

Hey guys,

Just finished working out all the bugs with my new setup. I was going to start tuning it (I'm using $32b). But it wouldn't go into closed loop. I figured this was do to a non heated O2 and long tubes. So I got a heated O2. I installed the ground on the firewall (where the tan wire goes from the firewall to passenger head). Then I found a wire behind my CD player that only got voltage with the ignition on.

So I datalog the car. Get it to about 155-160 and it idles in open loop. If I blip the throttle lightly it goes into closed loop. Then idles in closed loop for about 10 seconds then goes back to open loop. If I slowly raise the rpms it will go into closed loop at 1500rpms then go back to open loop when it goes back to idle. I took it for a drive. It stood in closed loop the whole time. I catch a red light. After about 10 seconds of idling it went into open loop. As soon as a left the light it went back into closed loop.

Any ideas?
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Old Oct 28, 2013 | 08:10 AM
  #2  
Dominic Sorresso's Avatar
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Re: Car only goes into closed loop when I give it any kind of throttle?

Headers? Coated?
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Old Oct 28, 2013 | 08:17 AM
  #3  
DeathStarr89's Avatar
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From: Davenport, Iowa
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Re: Car only goes into closed loop when I give it any kind of throttle?

Not familiar with your code mask but others like $A1 appear to be in open loop at idle. They don't use the o2 at ldle, but calculate engine airflow and base the BPW off of that.

Unchecking the "Idle BPW as a function of airflow" flag in that mask fixes it. Not sure if yours is the same though.
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Old Oct 28, 2013 | 11:42 AM
  #4  
IROCThe5.7L's Avatar
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From: Buffalo, NY
Car: 1988 IROC-Z
Engine: 427 SBC
Transmission: ProBuilt 700R4
Axle/Gears: Moser 12 Bolt / 3.73 TrueTrac
Re: Car only goes into closed loop when I give it any kind of throttle?

Originally Posted by Dominic Sorresso
Headers? Coated?
Yes. Jet hot coated Hooker 2210's.

Originally Posted by DeathStarr89
Not familiar with your code mask but others like $A1 appear to be in open loop at idle. They don't use the o2 at ldle, but calculate engine airflow and base the BPW off of that.

Unchecking the "Idle BPW as a function of airflow" flag in that mask fixes it. Not sure if yours is the same though.
Thanks for the reply. I'll look for that. I'm running the tune I had with my h/c/i L98 and that idled in closed loop. I just burned a new chip to raise the idle to get it running. And switched to $32b extended so I could turn off the added spark advance when data logging. I doubt switching to $32b extended would cause this but I will look for what you suggested. Thanks again for the reply.
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Old Oct 28, 2013 | 08:39 PM
  #5  
1991sleeper's Avatar
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I'd take the O2 out and ign ON and make sure the o2 heater is working properly thermometer or IR heat gun should b around 5-600 degrees I think before it is active ... I had this same EXACT problem with the stock 1 wire and put in a heated o2 and voila perfukto
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Old Oct 28, 2013 | 11:43 PM
  #6  
IROCThe5.7L's Avatar
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From: Buffalo, NY
Car: 1988 IROC-Z
Engine: 427 SBC
Transmission: ProBuilt 700R4
Axle/Gears: Moser 12 Bolt / 3.73 TrueTrac
Re: Car only goes into closed loop when I give it any kind of throttle?

Hmm. Maybe I can find someone with a heat gun. I was thinking maybe a voltage issue with the O2. But when the car comes to an idle the lights don't dim and they don't get brighter when I hit the gas.
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Old Nov 15, 2013 | 10:34 PM
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anesthes's Avatar
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Re: Car only goes into closed loop when I give it any kind of throttle?

Oddly enough, the FSM says the exact same thing will happen when running the car at idle. It speaks of revving the engine to heat up the o2 sensor.

Somewhat surprised that a heated o2 is having the same problem. The closed loop constants for $32 are what, min CLT and o2 crossing/sec right?

-- Joe
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Old Nov 17, 2013 | 08:35 PM
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Re: Car only goes into closed loop when I give it any kind of throttle?

Ground the O2 heater to the engine block, not the firewall.
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