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Old 10-31-2015, 10:53 PM
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Default Rich Running Engine

I have a bone stock '06 GTO LS2 in a 69 Camaro. The exhaust always smells rich, either idling or going down the road. Is this strictly a tuning issue or should I look elsewhere?

I believe the tune is factory other than turning off the various sensors that aren't being used. No cats installed. O2, MAF, crank and cam sensors are new.

I have a scanner, but have very little knowledge on how to read it. Is it the fuel trim I am looking for? What would be the correct readings?

Is there any other info I should provide to help?
Old 11-01-2015, 06:20 AM
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No cats will always make a car smell. Fuel trims should be under +/-5% combined between the long and short trims.
Old 11-02-2015, 07:57 AM
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Without a Wideband installed you really have no way of telling. Smell is not the best indicator when your running w/o cats.
Old 11-03-2015, 01:53 PM
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Also if you have longtubes on the car, it will throw your trims off as well, unless you tune your switchpoints. You need a wideband to tell for sure.
Old 11-03-2015, 05:08 PM
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So what you guys are telling me is that there isn't a way to lean out the mixture, if that's my problem, without wideband o2 sensors installed?

Fuel trim doesn't really tell me the mixture, just what the computer is telling the injectors what to do?
Old 11-03-2015, 06:36 PM
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Are you running in closed loop?
Old 11-03-2015, 06:40 PM
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The O2 voltage graphs fluctuate about 1/second. I would assume that's the way to tell...?
Old 11-03-2015, 07:48 PM
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Should be bouncing from 150 to 900 back and forth. If it is the pcm is targeting stoichmetric AFR. If the voltage stays high your lean, low your rich



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