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Old 07-13-2012, 03:37 PM   #1
gallacmic
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Runs good in open loop, Bad in closed loop

I bought me a live data scanner and my Eclipse is modified (bored out, bigger valves,310cc injectors, 12:1 vortech FMU and 255 hp walbro, t-3 turbo etc)
While the car is in open loop (cold) it runs great. The long term fuel trim is -0.79% which I would say is not bad considering 0% is what is ideal. But once the coolant temp reading hits 150 degrees then the long term fuel trim drops to -18% and the car starts bogging and then revs itself back up to keep it from dying. The fuel pressure is at 30 psi. So the interpretation I understand is that the ecu thinks the car is running too rich and so it cuts the fuel trim by 18% and this is an overcompensation hence the car bogging down. The wideband says 15.4 when it bogs. I replaced the o2 sensor with a brand new bosch so thats taken care of but it still does it. I suspect my map sensor might be bad because during idle the data logger says 1inHG and the vaccum/boost gauge says 16inHG. The missing link may be clogged? Do map sensors have an open and closed loop? If the map sensor is bad wouldn't the car run crappy in closed and open loop? Need some advice from someone with experience in tuning here!
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Old 07-13-2012, 07:40 PM   #2
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Re: Runs good in open loop, Bad in closed loop

Sounds like you already have figured out your problem. The Map sensor should be reading much lower at idle. Approx 19in.HG. I would remove missing link and try it again, if that doesnt fix it then replace the map sensor. I would think the car would run bad all the time as well but if you know its bad go ahead and fix that issue first.
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gallacmic (07-14-2012)
Old 10-18-2012, 12:35 PM   #3
gallacmic
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Re: Runs good in open loop, Bad in closed loop

I finally fixed my idle problem!! Heres how I did it!!
http://www.youtube.com/watch?v=ze4_BKpGoc8
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