Won't pass smog

Tiny
PCMENTOR29
  • MEMBER
  • 1985 TOYOTA PICKUP
  • 75,000 MILES
Uneven idle, not missing, HC jumps to 500 must be below 150 at idle.
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Friday, April 19th, 2013 AT 6:46 PM

7 Replies

Tiny
ASEMASTER6371
  • EXPERT
Give me all the readings.

Roy
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Friday, April 19th, 2013 AT 6:52 PM
Tiny
PCMENTOR29
  • MEMBER
Here's the readings at idle, I am going again to test Monday. I will post Thanks Roy. Pete
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Sunday, April 21st, 2013 AT 5:57 PM
Tiny
PCMENTOR29
  • MEMBER
It passed smog this morning. It still has some issue affecting closed loop operation that maybe you can help me with. Here's what we did to make it pass. Run at 2500 rpm for a few minutes until the engine sound changed. Ie went into closed loop. Then as fast as we could, run the test because the closed loop at idle was correct readings for about 45 seconds. Then after, the idle HC's went high like 500 and CO like 2.10.

Here's what I hope you can help me with: learning how to identify closed loop operation and to ultimately solve open loop from happening at idle. Thanks for your help. Pete
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Monday, April 22nd, 2013 AT 9:15 PM
Tiny
PCMENTOR29
  • MEMBER
Here's some of the troubleshooting I have done on this.
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Monday, April 22nd, 2013 AT 9:30 PM
Tiny
PCMENTOR29
  • MEMBER
I am reading some pdf in autoshop101. Com. You don't need to worry about explaining closed loop right now thanks
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Monday, April 22nd, 2013 AT 10:04 PM
Tiny
PCMENTOR29
  • MEMBER
Hi Roy, LC Engineering maker of my headers said to try a heated O2 sensor to get closed loop at idle. I got a 4 wire sensor Bosch 15703 to try. I am hoping most upstream sensors are the same. I will post my results. Pete
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Saturday, April 27th, 2013 AT 2:41 AM
Tiny
PCMENTOR29
  • MEMBER
I ended up installing a Chevy S-10 4 wire O2 sensor. I used a relay for the heater. Testing for volts it starts giving normal.2-.8 fluctuations almost immediately. Can you help me with the uneven idle problem as it has not gone away. Thanks
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Wednesday, July 10th, 2013 AT 9:22 PM

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