PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Big PCM problems after header install....

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Old Feb 22, 2005 | 01:11 PM
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Default Big PCM problems after header install....

https://ls1tech.com/forums/generation-iii-external-engine/280063-help-hooker-lt-post-install-bad-missfiring-02-codes-no-power-running-pig-rich.html

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Old Feb 22, 2005 | 01:27 PM
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Well I know leaks will cause the O2s to read lean and dump lotsa fuel in, unnecessarily at that. square up your leaks first, as far as the codes go, you're still on stock cam? I dunno why the 0300 code threw, but the other O2 codes are common after header installs. If you have access to any scanning/logging tools, check out your O2 signals and fuel trims. If you have a shot O2 or two, that would make your car run like crap too. When you removed the EGR did you have your PCM settings changed to support it as well? Just a few places to start...
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Old Feb 22, 2005 | 02:11 PM
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check the engine sensor fuse

Sounds like a wire for one of your front O2s melted and is hitting the header... this will cause the engine sensor fuse to blow and cause you to run speed density (which will cause it to run for **** if it's not tuned that way)

If there's an exhaust leak at the gasket that can cause problems too ... it can suck in oxygen and cause incorrect O2 readings making the car think you're running lean so it'll add tons of fuel
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Old Feb 22, 2005 | 03:15 PM
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Thanks guys, I'll take a look at those things.
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Old Feb 22, 2005 | 03:54 PM
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Originally Posted by horist
check the engine sensor fuse

Sounds like a wire for one of your front O2s melted and is hitting the header... this will cause the engine sensor fuse to blow and cause you to run speed density (which will cause it to run for **** if it's not tuned that way)

If there's an exhaust leak at the gasket that can cause problems too ... it can suck in oxygen and cause incorrect O2 readings making the car think you're running lean so it'll add tons of fuel
This happened to me a while back.. I only dynoed 300 and was like wtf...I had no idea what happened to cause it. I finally found the fuse blown. I remember having to tape up where the o2 sensor burnt thinking that was the proble at first. Glad to know what caused that....
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