Cam idle problems
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Joined: Apr 2004
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Cam idle problems So, i have a new 233/239 which ran great from lubbock down to houston. Here is what is different with my car, i have no front 02s on the drive, so i went under and put some 02s in. The car was fine in open loop, but once hit closed loop, idle drops down to 400-500 range not wanting to run. The race has been dyno tuned and only started this after the 02 install. I have reset the pcm and everything, so what could this be? It runs fine once moving around 1500rpms, so the first thing i can put this on is the computer.
Originally Posted by Z-286speed
So, i have a new 233/239 which ran great from lubbock down to houston. Here is what is different with my car, i have no front 02s on the drive, so i went under and put some 02s in. The car was fine in open loop, but once hit closed loop, idle drops down to 400-500 range not wanting to run. The race has been dyno tuned and only started this after the 02 install. I have reset the pcm and everything, so what could this be? It runs fine once moving around 1500rpms, so the first thing i can put this on is the computer.
If it was tuned for open loop (assuming MAF is fairly stock) it should run fine with everything hooked back up if it's an 01-02. If it's not 01-02, then the tuner is a jackass for not copying over the secondary stuff to the primary. 
Thread Starter
TECH Enthusiast
Joined: Apr 2004
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The MAF is stock. The car ran just fine from lubbock down to houston, 600 miles, went to 900 idle speed when the clutch was put in. But now its not doing that, its drops almost to 0 then bumps up to 400 or so. This was not happening before without the front 02s, then i tried putting in the front 02s and all hell broke lose, i took them out, pulled the PCM fuse and restarted, and ideas?
Unplug the sensors and make sure it's the 02s that are throwing it off. Borrow a scan tool and get some logs with the 02s installed and not installed (unplugged). Even in SD mode, your car will make fueling adjustments based upon 02 sensor feedback. These cars aren't made to run w/o them (if you are using the OEM PCM).
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