LT280z Posted March 9, 2007 Share Posted March 9, 2007 So heres the problem...the car is idling and everything appears to be working fine...All of the sudden it does the following at the same time Go's lean, voltage drops from 13.4 to 12.5, fuel pressure go's from 48 to 58....all at the same time and then the car dies....and IF it restarts it takes a while. Im thinking trash in the lines somewhere ? Car 77 280z megasquirt, 440cc inj, pallnet rail, aeromotive fpr, walbro pump, holset, etc Any ideas would be appreciated Quote Link to comment Share on other sites More sharing options...
vashonz Posted March 9, 2007 Share Posted March 9, 2007 obstruction/crimp between fuel pressure gage and fuel injector is my guess. less flow through injector ->lean more backpressure -> *indicated* fuel pressure goes up Unless the gage is mounted on the fuel rail. Then my guess is clogged injector. Quote Link to comment Share on other sites More sharing options...
LT280z Posted March 9, 2007 Author Share Posted March 9, 2007 pressure gauge is on the fuel rail as well as the regulator. I wasnt watching the gauge on the regulator only the one on the rail. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted March 10, 2007 Administrators Share Posted March 10, 2007 What method are you using to check your AFR's? Try disconnecting the vacuum source to the regulator, repeat and report. Quote Link to comment Share on other sites More sharing options...
LT280z Posted March 10, 2007 Author Share Posted March 10, 2007 What method are you using to check your AFR's? Try disconnecting the vacuum source to the regulator, repeat and report. LM1 I will go try this right now and report back with the results Quote Link to comment Share on other sites More sharing options...
LT280z Posted March 10, 2007 Author Share Posted March 10, 2007 Oh yeah, last night i checked the filter, removed the rail and injectors to check for debris and found nothing. Quote Link to comment Share on other sites More sharing options...
LT280z Posted March 10, 2007 Author Share Posted March 10, 2007 no changes while idling..same thing happens although the fuel pressure didnt rise. Quote Link to comment Share on other sites More sharing options...
Okimoto Posted March 10, 2007 Share Posted March 10, 2007 I'm going to be honest, I run SU's so all of this may or may not be relevant. Does the megasquirt use an injector resistor pack? Just a thought that could be totally wrong or off, but if there were those 'sand ballast' whatever type resistors that would short off on occasion, it could possibly cause that condition where you have less/no activity at the injectors? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted March 10, 2007 Administrators Share Posted March 10, 2007 Okie dokie.. That helps a bit. 1) The rise in fuel pressure… Your rise in fuel pressure previously was due to the fact the engine started to run like crap and as result, manifold pressure went way up, i.e. loss of vacuum, hence the fuel pressure regulator not getting a vacuum signal and allowing the fuel pressure to come up to full. 2) In reference to Okimotos question, are you using the stock OE injectors? If so, without the resistor pack, "maybe" there is a chance the high current draw of the stock Datsun injectors is to much for the MS drivers?!? (This is more Mobythevan and Z-ya Pete’s territory, maybe they’ll chime in on that one…) 3) You mentioned a voltage drop in the electrical system. MS does have an adjustment for voltage variations which is there to help keep the “actual†injector pulse width consistent with varying vehicle voltages. It could be that your voltage compensation is either over or under compensating when this voltage drop happens? Of course, the fact that the voltage drop is taking place in the first place needs to be address as well. After you confirm your injector situation, I’d work on fixing that voltage issue. Hope that helps… Quote Link to comment Share on other sites More sharing options...
LT280z Posted March 11, 2007 Author Share Posted March 11, 2007 Let me give a little background info on the situation. The car was running like a champ for several weeks. I took the front cover off to fix an oil leak last week, retimed the motor, reset the timing in the megasquirt, started the car and now i have this problem..so nothing has really changed since the car was running great except for resetting the timing (and the timing is correct on the motor and the ms&s. I go from having a great running car to a car that wont hardly start and is missing like crazy when it gets into boost and nothing has really changed. It idles smoothly and runs smoothly out of boost but if i stab the throttle and try to get into the boost it will backfire and start to die out. Supra 440's Yes i run a resistor pack voltage hasnt been an issue thus far and the car WAS running great for several weeks. after inspecting the fuel system im starting to think its electrical/ms&s related... Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 12, 2007 Share Posted March 12, 2007 I don't think this happens unless you are running MSII and the flyback but I and others get an occassional PW spike. It happens so fast sometimes it doesn't show on the log but when it does it is like 32ms, very noticable. Anyway, when it happens at idle it kills it. Quote Link to comment Share on other sites More sharing options...
LT280z Posted March 13, 2007 Author Share Posted March 13, 2007 latest developments http://forums.hybridz.org/showthread.php?p=747509#post747509 Quote Link to comment Share on other sites More sharing options...
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