zdrifter280 Posted March 24, 2007 Share Posted March 24, 2007 So a couple of days ago my 83 zxt started running like s**t ! When its cold and i start it it has to warm up before i can even touch the gas or it boggs and pops threw the intake and even after it warms up it still does it up till like 3k rpm but its driveable, and it done this once before like a month ago but it fixed itself and has been fine since . I have done the Z31 ECU converstion and am running an SAFC-2 and 240sx tps and it has been running perfect for the past several months with that setup . I have tested and checked everthing i can think of the fuel pressure is @ 35 at idle and 40 when i open the throttle the CHTS is giving the correct ohm readings the dist. timing is at 20* btdc the cam timing is on compression is good i have never been running the cold start stuff there are no boost leaks ive checked all the wiring several times idk what else to do does anybody have any other ideas ?! Quote Link to comment Share on other sites More sharing options...
rdsk8ter Posted March 24, 2007 Share Posted March 24, 2007 So a couple of days ago my 83 zxt started running like s**t ! When its cold and i start it it has to warm up before i can even touch the gas or it boggs and pops threw the intake and even after it warms up it still does it up till like 3k rpm but its driveable, and it done this once before like a month ago but it fixed itself and has been fine since . I have done the Z31 ECU converstion and am running an SAFC-2 and 240sx tps and it has been running perfect for the past several months with that setup . I have tested and checked everthing i can think of the fuel pressure is @ 35 at idle and 40 when i open the throttle the CHTS is giving the correct ohm readings the dist. timing is at 20* btdc the cam timing is on compression is good i have never been running the cold start stuff there are no boost leaks ive checked all the wiring several times idk what else to do does anybody have any other ideas ?! ok check the fuel volume. you can do this by hooking up a fuel pressure gauge and have the car running. the fuel volume is diffrent then the pressure hit the dump on the fuel pressure tester the fuel pump should instantly have re pressurized and the engine should run without a flaw. if it stumbles you could have a bad fuel pump. another way to test the fuel pump is to put an amp probe on it and watch it if its all over the place he pump is bad. another thing i dont know if this car has it but the crankshaft sensor and camshaft sensor need to be sycronious(sorry i cant spell) see if there is a way to reset it through the computer. if either sensor is bad it will cause the injector to fire at the wrong time like when the exhaust port is opening witch is bad. finally ohm out your wires the correct way to see if a wire is good is 1 find both ends of the wire and dissconnect it 2 come off the positive side of the batt and hook a 10ohm resistor to a volt meter what this will show you is if the wire is good under load (it might ohm out all day long but with the load might fubar) 3 out your tester in parrell with the wire and ground the other end (i know your saying direct short right dont forget you have a 10 ohm resistor in there). 4 the volt reading should be very close to the batt voltage i.e. 12.5 batt 12.0-12.5 on the wire if you drop more then 1/2 volt your wire has to much resistance and should be replaced. have you checked all the vaccume lines and intake gasket? a good way to do this is take a mapp gas torch and have the car running trigger the gas release but do not light the torch follow all the vaccume lines and go around the intake if there is a leak you will hear the engine rev up this is a great way to find the leaks. finally do you have a means for checking your gas useage ie short term long term it would help further the diagnosis Quote Link to comment Share on other sites More sharing options...
zdrifter280 Posted March 24, 2007 Author Share Posted March 24, 2007 what do you mean gas usage ? if you mean mpg it is s**t like close to 10mpg . I havent gotten a chance to test the fuel pump and circuit but it is getting fuel up top in the rpm band it really only boggs under 3k rpm . Quote Link to comment Share on other sites More sharing options...
rdsk8ter Posted March 24, 2007 Share Posted March 24, 2007 what i mean by that is do you access to a scanner that can get into your ecu this will tell you what your fuel is doing short term should very no more then .5-.5 and long term could be drastically diffrent. this will tell you how the engine is running Quote Link to comment Share on other sites More sharing options...
zdrifter280 Posted March 25, 2007 Author Share Posted March 25, 2007 No i dont have access to one of those . But i've found that when i start it cold if i add like 20% fuel with the AFC that it will somewhat fix it though and i dont have to wait for it to warm up to drive it ! Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted March 25, 2007 Share Posted March 25, 2007 Sound like your running lean. Could be a vaccumme leak. or lots of other things. You need to watch your FP under load. Check vaccumme lines , injector seals , manifold gasket etc... Quote Link to comment Share on other sites More sharing options...
rdsk8ter Posted March 25, 2007 Share Posted March 25, 2007 sounds like a vacume leak for sure try the tortch thing Quote Link to comment Share on other sites More sharing options...
zdrifter280 Posted March 25, 2007 Author Share Posted March 25, 2007 I havent done the torch thing but i have hooked a air hose up to the compressor inlet of the turbo and ran like 30psi threw the whole system and dont hear any leaks ! Quote Link to comment Share on other sites More sharing options...
rdsk8ter Posted March 26, 2007 Share Posted March 26, 2007 you might not hear a leak thats wht im getting at a pin hole could jack the entirs system up Quote Link to comment Share on other sites More sharing options...
rdsk8ter Posted March 31, 2007 Share Posted March 31, 2007 anything figured out yet i might still be able to help just needed those anwsers Quote Link to comment Share on other sites More sharing options...
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