§∂enz Posted July 27, 2010 Share Posted July 27, 2010 I have a fi 77 280z and i just recently got it. it has a newer head and injectors. under 3500rpm it seams to pull strong and sounds healthy but between 3500 and 4800 it sounds kind of sick, then at 4800 its like im hitting rev limiter and the car cuts out and won't rev any higher. I thought maybe my tach was wrong and it WAS rev limiter but i checked my manuel and saw i should be able to go 60 in second and i can only go about 48/50 so something is definetely up. could it be the coil? i can tell its the original from 1977 but would a coil run strong then cut out as load increases? i'm really not sure here any help is great, thanks guys, -kyle Quote Link to comment Share on other sites More sharing options...
240zBoy Posted July 27, 2010 Share Posted July 27, 2010 It might be sending to much fuel to the motor and causing it to bog down. I doubt the coil would cause such an extreme loss of power like that. Quote Link to comment Share on other sites More sharing options...
Daphur280 Posted July 27, 2010 Share Posted July 27, 2010 I'm going through a similar issue, I'm running a L28et in my 73 240z, and when first installed I had the stock turbo FPR feeding into a JSK fuel rail, running stock turbo injectors, and the fuel pressure gauge on my fuel rail was reading 24psi at idle and 30psi whil revving (dont have tach so i dont know at what rpm's). I was told this is too low of a setting, so I bought an adjustable FPR and set it to 35-40psi and it cuts out at what sounds like 4500-5000rpms... should I return the setting to 20psi??? Quote Link to comment Share on other sites More sharing options...
§∂enz Posted July 27, 2010 Author Share Posted July 27, 2010 so you think its fuel delivery then? could it be a clogging fuel filter? Quote Link to comment Share on other sites More sharing options...
Daphur280 Posted July 27, 2010 Share Posted July 27, 2010 So far this is the only way I can visually see something (aside from the audible noise) of whats occuring: Quote Link to comment Share on other sites More sharing options...
Daphur280 Posted July 27, 2010 Share Posted July 27, 2010 (edited) so you think its fuel delivery then? could it be a clogging fuel filter? quite possibly, do you have a pressure gauge to check the fuel pressure? Edited July 27, 2010 by Daphur280 Quote Link to comment Share on other sites More sharing options...
§∂enz Posted July 27, 2010 Author Share Posted July 27, 2010 (edited) the weird thing is now that i think about it the car acts like it runs rich...uhg i don't know... and no, i don't have a presure gauge. i could try taking away the fuel filter just for a bit and see if it works. its not like 10 minutes without one will hurt anything...i hope haha Edited July 27, 2010 by §∂enz Quote Link to comment Share on other sites More sharing options...
§∂enz Posted July 27, 2010 Author Share Posted July 27, 2010 okay update, I checked the fuel filter and its fine. In regards to the first post; what could cause the car to run rich enough at high rpm to make it cut out like that? Quote Link to comment Share on other sites More sharing options...
Daphur280 Posted July 27, 2010 Share Posted July 27, 2010 okay update, I checked the fuel filter and its fine. In regards to the first post; what could cause the car to run rich enough at high rpm to make it cut out like that? afm out of adjustment Quote Link to comment Share on other sites More sharing options...
palauoriginal Posted July 28, 2010 Share Posted July 28, 2010 i have been having a similar problem usually under higher loads like spirited driving or going up a hill i am also suspecting an afm/fuel related problem. would be awesome to find anything more on this Quote Link to comment Share on other sites More sharing options...
240zBoy Posted July 28, 2010 Share Posted July 28, 2010 Another thing I forgot to mention... check the fuel line for any kinks it might have or un neccesary routes of the line. Most likely not it as that would cause fuel pump issues but I guess the best thing to do first is to check what type of pressure your getting. FYI things normally go wrong in places where we tinkered with so checkout those injectors and rail and make sure it's properly installed. Quote Link to comment Share on other sites More sharing options...
§∂enz Posted July 28, 2010 Author Share Posted July 28, 2010 okay how do i adjust the afm? Quote Link to comment Share on other sites More sharing options...
jbehuniak Posted July 28, 2010 Share Posted July 28, 2010 okay how do i adjust the afm? http://atlanticz.ca/zclub/techtips/EFI&fuel.htm read afm adjustment and spring calibration.... its alot easier then it seems though. Quote Link to comment Share on other sites More sharing options...
§∂enz Posted July 28, 2010 Author Share Posted July 28, 2010 okay thanks a lot. I will be doing that today, and also getting a new coil (i know thats not it but they're cheap, and my 33 year old one can't be working as good as it should...) I'll report here when done. wish me luck haha. Quote Link to comment Share on other sites More sharing options...
§∂enz Posted July 29, 2010 Author Share Posted July 29, 2010 okay, so with a new coil and plugs it will now rev to redline however there is NO power up there, like none. i don't think it could push itself up to rev limiter but it deosn't cut out anymore...so i thought "okay it must be running way rich and since it now has a better spark it can burn off more of the fuel." so i then leaned out the afm and it runs no different...:/ i can make it leaner or richer and it still won't have power in the high rpms. these cars should pull well into redline right?! i saw max power is supposed to be at 5200rpm-ish and i KNOW i make almost no power there right now... thoughts? i'm stumped right now... thanks, kyle Quote Link to comment Share on other sites More sharing options...
jbehuniak Posted July 29, 2010 Share Posted July 29, 2010 what else have you done to diagnose it. Did you gap the plugs correctly? Is your vacuum line connected to your distributor? have you checked the diaphragm to see if it holds vacuum at your distributor? What timing are you running on your car? Quote Link to comment Share on other sites More sharing options...
Daphur280 Posted July 29, 2010 Share Posted July 29, 2010 http://atlanticz.ca/zclub/techtips/EFI&fuel.htm read afm adjustment and spring calibration.... its alot easier then it seems though. Where can I find one of these for the turbo AFM? Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 29, 2010 Share Posted July 29, 2010 The AFM is out of the photo altogether by 3500 rpms, the 'tuning' of it generally makes that number higher or lower by tighter or looser. After it's wide open (3500 stock) the ECU is on a purely programmed fuel curve of RPM and wether or not the WOT switch is closed or not. Red Herring there. This is purely electrical. Clean your connections on the EFI system completely and include the ones on the ECU and ECU plug. Quote Link to comment Share on other sites More sharing options...
§∂enz Posted July 29, 2010 Author Share Posted July 29, 2010 where even is the ecu on these cars? and could it be the cold start injector being on when it's not suposed to? Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 30, 2010 Share Posted July 30, 2010 The FSM, which is avaialbe for free download is available in the FAQ via links. This will answer your question on everything regarding this issue. Quote Link to comment Share on other sites More sharing options...
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