s!lvias30 Posted November 27, 2009 Author Share Posted November 27, 2009 Thanks for the links , very helpful Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted November 30, 2009 Author Share Posted November 30, 2009 Well got the on just one weird issue , I think my car is running on my cold start valve only I think because while the car stayed on I unplugged all the injector clips and the car still stayed on and nothing happened but when I unplugged the cold start valve the car shut off , what can be the issue ? Why is my car still running on with only the cold start valve , it revs up to 3200 only I just don't know now because I checked my injectors if the click when I connect them to a 9volt battery and yes they still click , unless they are stuck open , could that be the issue ? How can I check if I'm getting power to my injector Clips and also how do I know if the injector resistors are working ok Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted December 1, 2009 Administrators Share Posted December 1, 2009 Revs to 3200 RPM and no more, like a violent rev limiter? Shuts off at 3200 RPM and comes back on at say approx. 2800 RPM? Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 1, 2009 Author Share Posted December 1, 2009 Something like that , it just weird because I unplugged all the injector connectors and I rev it and it does the same thing so my car is running of the cold start valve only, unless the injectors are stuck open Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 1, 2009 Author Share Posted December 1, 2009 Ok I know I'm not getting power because I turn on the car with just the cold start valve connected and then unplugged it and quickly plugged a injector connector on and nothing no power Quote Link to comment Share on other sites More sharing options...
JSM Posted December 1, 2009 Share Posted December 1, 2009 Paul, he's not getting power to the injectors for some reason. We can run the entire car off the cold start injector alone. We unplugged each injector one by one and the car still idled great. Remove the cold start injector plug and she dies. I was under the impression the CS valve was only supposed to squirt for the first 12 seconds and then no more? I left as we were running out of light. Quote Link to comment Share on other sites More sharing options...
JSM Posted December 1, 2009 Share Posted December 1, 2009 Sammy, check grounds again. Look at page 6 and 7. Test each resistor with an Ohm meter. I'm thinking you should check ground from the negative side of the injectors to the chassis, as well as to the ECU, If I'm reading this correctly? If you plug everything back in and look at page 20, there is a schematic. You should be able to test the entire system from the plug going into the ECU. It gives you the pin #'s and everything on Page 20. Also scope out page 33. Do the check on the power relay. Actually print the whole darn book out and do all the checks in the book from top to bottom! Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 1, 2009 Author Share Posted December 1, 2009 ok i will do that , that is the only thing i can think of that is wrong Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 3, 2009 Author Share Posted December 3, 2009 bump Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 3, 2009 Author Share Posted December 3, 2009 Ok now I kind of know what is going on , cold start valve stays on. It on shut off to tell my injectors to turn on , what can I do to fit this issue ? Could I run switches? Or what ??? Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 3, 2009 Author Share Posted December 3, 2009 So one please help me , I tookit a michanic and they don't know either , what is a easy fix to make my cold start to shut off to tell the computer to turn on the injectors Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted December 3, 2009 Administrators Share Posted December 3, 2009 Paul, he's not getting power to the injectors for some reason. We can run the entire car off the cold start injector alone. We unplugged each injector one by one and the car still idled great. Remove the cold start injector plug and she dies. I was under the impression the CS valve was only supposed to squirt for the first 12 seconds and then no more? I left as we were running out of light. Roger that. It was starting to sound like TPS short out like when we wash the engine bay.. Ok now I kind of know what is going on , cold start valve stays on. It on shut off to tell my injectors to turn on , what can I do to fit this issue ? Could I run switches? Or what ??? Delete the cold start system all together, especially living in Florida! Cold start is just that, it is for cold starts. I mean really cold starts, like in the fridgid white north, and at that, it is debatable if it is truly needed. Even up here in Oregon where we will see temps below freezing in the morning when we go out to start our cars, on all the 280-Z’s that I have deleted the cold start injector, my cars, customer cars, friends cars, several cars, all of those cars still start just fine, even on the really cold mornings. Cold start injector circuit is not needed. When well below freezing, the cold start injector may help the engine to fire off a couple of crankshaft revolutions earlier vs. not having it, but if your battery is good, those couple extra revolutions are not an issue. In Florida, you shouldn’t notice its function anyhow. Remove the cold start injector and put a plate over the hole, (using some gasket material to seal it). In a pinch, just cut the fuel line going to the cold start injector, plug it on the fuel rail side or install a plug in the fuel line itself so visually it looks OE. Electrically, you can just leave it plugged in or just unplug it, wont hurt the ECU or anything else. Hope that helps. Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 3, 2009 Author Share Posted December 3, 2009 Ok but doesn't the computer read if the cold start is on and then tells the ecu that the car is on , then the injectures fire up and the cold start shuts off, the problem is that the injectors won't fire still Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted December 3, 2009 Administrators Share Posted December 3, 2009 Ok but doesn't the computer read if the cold start is on and then tells the ecu that the car is on , then the injectures fire up and the cold start shuts off… These early ECU's are not thinking ECU's. I.e. not like modern OBD-II cars. This EFI is very simple, just like most basic electrical circuits in the car. again, not a thinking ECU. The Z car ECU does NOT read from the cold start system. I have been tinkering, monkeying with and researching this EFI system since the late '80's have learned TONS about it in that monkeying, such as how and when it fuels, what sensors do what and why, etc. Successfully got a 2800 lb 280-Z with stock EFI and stock cam to run 14.4 @ 97 MPH, (0-60 MPH in 5.7 seconds), while delivering 28-30 MPG on the freeway! Played with mechanical actuation of the AFM in and effort to remov it from the air stream, various TPS switches with WOT clocked at different positions, micro switches added the throttle linkage that were tied into resistors that altered the water temp signal at various throttle positions for specific fueling under various conditions, etc. What I learned was the stock EFI is very robust, is limited in how far you can tune it, is quite easy to diagnose and the cold start system is all but entirely useless. I have successfully removed the cold start system in varying degrees of "deletion" on at more than 100+ Z cars. In short, just delete the cold start system. It is doing you and your car no good and possibly only adding undue confusion to your situation! Trust me! …the problem is that the injectors won't fire still Ok, lets gone on to the problem at hand. a) You have fuel pressure. b) You have ignition as the engine will run a supplement fueling source. 1) You mentioned spare ECU's. Being as ’78, it is its own regarding ECU pin out and harness. You can not mix a 78 ECU or harness with any other year ECU or harness. 2) Do you still have the dropping resistors near the clutch master cylinder plugged in? 3) Do the injectors “click-click-click†while cranking on the starter? Using a mechanics stethoscope, listen to the injectors! 4) With key ON, check for battery voltage at the injectors themselves. You should have voltage, (approx 10 volts or so) at both terminals of each injector connectors. I know, that sounds weird that both are hot, but that’s the way it is. If you do have power, need to find out why they are not getting the pulse signal. If no power then start tracing the power wire from the battery, fuel inj. relay, fusible link in the EFI power harness near the battery? etc. 5) If you have power to the injectors, adequate fuel pressure, but no clicking injectors, (it runs on supplement fuel so we know the ignition system is working), verify the ECU is getting the engine RPM signal. 6) Does the tach move while cranking the engine over? If no, more than likely your ECU isn’t getting the RPM signal, as well as the tach, (ECU and tach get their signal from the same wire). Under the dash, driver side follow the ECU harness from the ECU to a small run of wires that come out of it to a 6 connector plug. Only 5 of those connectors are being used. One will be the RPM signal. 7) Just for giggles, unplug the little spade connector from the starter and turn the key to "start"! Do you hear the fuel pump come with the key in the start position? I’ll stop there for now. Go check this stuff, report back with your findings and we’ll move on from there. I may not reply right away, maybe even a day or so between replies, but I will try to help as I can. Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 3, 2009 Author Share Posted December 3, 2009 Plus when I unplugg the cold start the car dies . How do I eliminate the cold start and have the injectors to work , none of my injectors are working and I think it is because the computer is reading that the cold start is still on and the motor is not on so the injectors won't fire up , because All my relays are new and my wiring harness is new also all the grounds are on and new sensor , the last thing in my mind is that the FSM said the cold start valve turns on with the ignition switch andthen turns off when the switch goes back to on and he car is on so in theory I think my switch is bad but i don't know really . Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 3, 2009 Author Share Posted December 3, 2009 Ok give me a second and I will do all of those steps Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 3, 2009 Author Share Posted December 3, 2009 How can I identify a 1978 ecu? I have two 1977 ecu and one 1978 Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 3, 2009 Author Share Posted December 3, 2009 1) You mentioned spare ECU's. Being as ’78, it is its own regarding ECU pin out and harness. You can not mix a 78 ECU or harness with any other year ECU or harness. 2) Do you still have the dropping resistors near the clutch master cylinder plugged in? 3) Do the injectors “click-click-click†while cranking on the starter? Using a mechanics stethoscope, listen to the injectors! 4) With key ON, check for battery voltage at the injectors themselves. You should have voltage, (approx 10 volts or so) at both terminals of each injector connectors. I know, that sounds weird that both are hot, but that’s the way it is. If you do have power, need to find out why they are not getting the pulse signal. If no power then start tracing the power wire from the battery, fuel inj. relay, fusible link in the EFI power harness near the battery? etc. 5) If you have power to the injectors, adequate fuel pressure, but no clicking injectors, (it runs on supplement fuel so we know the ignition system is working), verify the ECU is getting the engine RPM signal. 6) Does the tach move while cranking the engine over? If no, more than likely your ECU isn’t getting the RPM signal, as well as the tach, (ECU and tach get their signal from the same wire). Under the dash, driver side follow the ECU harness from the ECU to a small run of wires that come out of it to a 6 connector plug. Only 5 of those connectors are being used. One will be the RPM signal. 7) Just for giggles, unplug the little spade connector from the starter and turn the key to "start"! Do you hear the fuel pump come with the key in the start position? Ok yes I put the 1978 computer , next deleted the cold start, the resistor plugs are in and all good, third the injectors don't click when firing, fourth the injectors are all getting exactly 12 volts each pin so there is power , then yes the tac moves like 1/4 of a inch when crankking the motor on . Finally the car is ran by a switch staight to the battery Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 3, 2009 Author Share Posted December 3, 2009 Now what? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted December 4, 2009 Administrators Share Posted December 4, 2009 First we need to verify a few things, just in case. You are using a ’78 ECU and a ’78 harness correct? You mentioned rewiring the ’78 harness using a manual. What manual did you exactly use for that? If the OE Nissan service manual which year? … and I think it is because the computer is reading that the cold start is still on and the motor is not on so the injectors won't fire up …. I'll cover this again. The ECU does not read or sense the cold start anything! The ECU doesn’t know or let alone care if the cold start injector is open, closed, or even installed on the engine! It does not use anything from the cold start to base or control the other injectors! Yes it may very well be opening up allowing fuel into the intake which your engine is running on until the cold start injector closes. For the intent of this discussion and your current EFI issues, the cold start system does not pulse nor is in any way affiliated with the 6 main injectors. It just opens for a few seconds and that’s it! It appears to be operating by your description, but again, it has absolutely, positively, 100% NOTHING to do with the rest of your injectors operating or not operating, unless you accidentally wired it to. They are supposed to be two completely different and separate systems! In this link given earlier; http://atlanticz.ca/zclub/techtips/efisystem/280zfuelinjectionbook.pdf Page 16 and page 17 covers the cold start system, (Thermo time switch controls the cold start injector). How can I identify a 1978 ecu? I have two 1977 ecu and one 1978 I don’t recall part numbers, but you will notice the pin out of the ’78 is totally different from the ’77. Your harness is ’78 correct? You mentioned your rewired back to ’78 specs per the service manual? The ’78 Nissan service manual? If you went by the Haynes manual, it doesn’t cover the ’78, only the ’75-’77. Ok yes I put the 1978 computer , next deleted the cold start, the resistor plugs are in and all good, third the injectors don't click when firing, fourth the injectors are all getting exactly 12 volts each pin so there is power , then yes the tac moves like 1/4 of a inch when crankking the motor on . Finally the car is ran by a switch staight to the battery 1) Power to the injectors, good! 2) Fuel pressure, good! 3) Engine actually runs on supplemental fuel, good! 4) Tach is moving/bouncing while cranking, good! 5) Injectors are not clicking while cranking. Now we have a more definitive focus for troubleshooting. Need to find out why the ECU is not pulsing the injectors. Verify the ECU itself is getting power. (Just because the injectors have power does not mean the ECU is getting power). Just as JSM covered previously, unplug the ECU and using the correct wiring diagram, verify that you have 12v to all the pins that are supposed to be hot. You may have to turn the key to on. Quote Link to comment Share on other sites More sharing options...
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