Subject	almost sounds like an open loop vs closed loop issue
Posted by	aliaZ on April 25, 2012 at 6:04 AM
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In Reply To	Stumble at low rpm, kinda stumped. posted by Woody75 (Denver) on April 24, 2012 at 10:43 PM
Message	being that it smooths out as the ecu crosses over into the open loop part of the map. is the severity of the stumble dependent on engine temperature? Have you checked to see what temp the ecu is reading through your laptop? Can you check A/F to see if it is fuel or ignition related? Have you checked for intake valve deposits? A bunch of carbon buildup on the back side of the valves can cause what you're describing. Any exhaust leaks upstream of the O2 sensors? Look for anything that may fool the O2 sensors into reading a false condition. How is the exhaust cam drive pin for the CAS?
Follow Ups	Stumble at low rpm, kinda stumped. - Woody75 (Denver) 22:43:52 04/24/12 Still have EGR? - Joe@ZSpeedperformance 23:25:02 04/24/12 Tried it, no change. (n/m) - Woody75 (Denver) 22:26:42 04/25/12 Have you tried a different ECU? - toykoz32 01:19:49 04/25/12 Yep, it in my list I posted. (n/m) - Woody75 (Denver) 09:06:48 04/25/12 almost sounds like an open loop vs closed loop issue - aliaZ 06:04:21 04/25/12 Answers. - Woody75 (Denver) 09:11:08 04/25/12 Same.... - 300ZMang 09:03:34 04/25/12 suspect dying injector or bad coil or injector connection - Dane (Houston) 09:59:33 04/25/12 Coils have been proved out. - Woody75 (Denver) 10:32:01 04/25/12 I have seen injectors cause this, even Nismo's that ohmed - marklar182 10:08:56 04/25/12 As have I. - Woody75 (Denver) 10:32:53 04/25/12 if you have an injector that is underflowing - aliaZ 11:23:26 04/25/12 I'm leaning towards this post, and the AR post below. - CoHPhasor 21:43:46 04/25/12 FPC has been swapped out already (orginal post) - Woody75 (Denver) 22:22:51 04/25/12 Right, but how's the voltage? - CoHPhasor 01:53:29 04/26/12 Had this issue for the last 2 months and fixed it 2 days - HK'S Z 12:02:32 04/25/12 Checked it, its good. - Woody75 (Denver) 22:24:45 04/25/12 Suspect VTC gear or oil pressure to VTC (n/m) - OverZealous (CT) 22:55:11 04/26/12 Re: Stumble at low rpm, kinda stumped. - AsaHerring 12:39:31 04/25/12 Was the cas/pin rusted when you pulled it out? - Joe@ZSpeedperformance 08:39:06 04/26/12 Aliaz already asked this. - Woody75 (Denver) 09:09:27 04/26/12 vacuum leak? - TriniTT 10:28:55 04/26/12 What about the TPS sensor? - DVDBURN (MD) 20:43:45 04/26/12 It reads fine. - Woody75 (Denver) 09:26:54 04/27/12 You didn't say anything about the TPS in your OP. (n/m) - DVDBURN (MD) 10:08:06 04/27/12 Oh damn, sorry. Just saw that. (n/m) - Woody75 (Denver) 10:15:38 04/27/12 Sounds like sensor or fuel delivery. - DVDBURN (MD) 10:54:55 04/27/12 Few updates - Woody75 (Denver) 22:32:41 04/27/12 I had a PTU go bad before where it caused - KongZTT GT28RS MD 22:52:58 04/27/12 "Swapped out PTU" (from original post) - Woody75 (Denver) 11:45:49 04/28/12 sorry.. didnt read it thoroughly :) - KongZTT GT28RS MD 12:54:59 04/28/12 Couple thoughts for you - 300ZMang 08:38:17 04/30/12
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