Derek Posted August 27, 2011 Share Posted August 27, 2011 (edited) Ok Maybe it's not that dramatic. I've had this problem since I first set up my megasquirt. My car is a little touchy rolling off of idle. If I release the clutch a little to aggressively the car starts to die and then goes into a full lean condition. Pressing the throttle makes no difference. the only recovery is to restart if it died or shut it down and restart. It has only happened 4 or 5 times but it could be really a problem if I jump out a little to quickly into traffic and the car dies. It seems like it jumps into flood clear mode. Unfortunately it never happens when I'm logging. Has anyone got any ideas on this? Thanks Derek Edited August 27, 2011 by Derek Quote Link to comment Share on other sites More sharing options...
Tennesseejed Posted August 27, 2011 Share Posted August 27, 2011 MSQ would help. 60mm TB? I'm warming up to the notion that a 60mm TB is too large for smooth off idle transition on a NA build. What ignition? Edis? MSD? Other? Quote Link to comment Share on other sites More sharing options...
Leon Posted August 27, 2011 Share Posted August 27, 2011 (edited) I'm guessing Derek's using his custom ITBs and EDIS? Derek, are you running TPS or MAP based fueling? Also, do you have your ignition map set up with idle timing slightly retarded and the cells around idle advanced? This makes for a more stable idle. Edited August 27, 2011 by Leon Quote Link to comment Share on other sites More sharing options...
Tennesseejed Posted August 27, 2011 Share Posted August 27, 2011 I'm guessing Derek's using his custom ITBs . . Ah yes, I should have recognized that. Alpha-N is something I haven't sucessfully fiddled with. *Bows out and wishes best of luck* Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 27, 2011 Share Posted August 27, 2011 Alternating, 2-squirts? Quote Link to comment Share on other sites More sharing options...
Derek Posted August 27, 2011 Author Share Posted August 27, 2011 Alternating, 2-squirts? Simultaneous 2 squirt. Derek, are you running TPS or MAP based fueling? Also, do you have your ignition map set up with idle timing slightly retarded and the cells around idle advanced? This makes for a more stable idle. Map based fuel. TPS based acceleration. I think I'll start data logging and then go out in the parking lot and keep trying to make it happen. I was kind of hoping that someone would be like "yep had the same thing happen to me try XXX" Hey a guy can dream right! I'll post the log when I get something worth looking at. Derek Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 27, 2011 Share Posted August 27, 2011 (edited) FWIW, I get better throttle tip-in with Alternating. I also get the best results from 80% Map and 20% TPS AE. Edited August 27, 2011 by cygnusx1 Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 29, 2011 Share Posted August 29, 2011 Two things to look at: 1) Check that Cranking RPM is around 300 rpm and not higher. If the engine stumbles as you start and the rpm temporarily drops below this threshold, the ASE cycle starts again and depending on how rich it's set, it can cause the engine to stumble or even stall. Before I realized the consequences of this, I had it set higher ~500 rpm and symptoms were similar to what you describe. 2) Check that the VE table in the upper left corner is properly tuned. Again, if the revs drop as you start up, this is the part of the MAP that will be active and it may be too lean (or too rich). Other than that, perhaps post your MSQ file if you can't capture this logging. Quote Link to comment Share on other sites More sharing options...
Derek Posted August 29, 2011 Author Share Posted August 29, 2011 Thanks for the info guys. I'll check it out tomorrow and post back. Derek Quote Link to comment Share on other sites More sharing options...
Derek Posted August 29, 2011 Author Share Posted August 29, 2011 2) Check that the VE table in the upper left corner is properly tuned. Again, if the revs drop as you start up, this is the part of the MAP that will be active and it may be too lean (or too rich). And that fixed it. Thanks Daniel you may have saved my life I guess I should get off of my but and do a proper tune. Thanks again everyone for the help Derek Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 29, 2011 Share Posted August 29, 2011 (edited) I guess I should get off of my but and do a proper tune. If you haven't checked it out, the recent versions of TunerStudio have an automatic tuning function he calls VE Analyze that works fabulously. You just start it up and drive. You do need to give it the delay settings for the O2 sensor and the defaults are too short based on my experience, especially if you've got the sensor mounted after the collector on an L6 header. Also, I've found that it doesn't do a good job tuning for idle, but you can lock those cells out. So manually tune idle, and let VEA do the rest. Daniel Edited August 29, 2011 by Zmanco Quote Link to comment Share on other sites More sharing options...
FricFrac Posted September 1, 2011 Share Posted September 1, 2011 Just wondering if you're running the MAP with runners from each individual throttle body tied together to give you a more stable MAP sensor reading at idle? Quote Link to comment Share on other sites More sharing options...
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