S30Grit

280Z Requires Starting Fluid for Cold Starts

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    One more possibility - bad or disconnected ground on EFI circuit.  It's been known to happen.  It's the wire at the negative terminal of the battery with the plastic connector.

    Confirm power to the injectors.  While starting.

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    25 minutes ago, Zed Head said:

    One more possibility - bad or disconnected ground on EFI circuit.  It's been known to happen.  It's the wire at the negative terminal of the battery with the plastic connector.

    Confirm power to the injectors.  While starting.

    Interesting... The negative side of my battery only had one thick wire to it, nothing else.  It went straight to the big engine/transmission ground bolt (cleaned it up).  Maybe that plastic connector/wire is "grounded" somewhere else, or maybe it's just dangling back there somewhere.  Any ideas where that EFI ground comes from or where I should look?

    Next time I'm with it, I'll definitely check power to the injectors during starting.

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    It's supposed to be attached to the firewall near the battery.  It looks like the one that goes to the positive terminal.  They sit close to each other and sometimes get switched by accident.

    You don't show the ground test in your list.  Testing grounds is probably the most commonly overlooked test for automotive electrical problems.

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    5 minutes ago, Zed Head said:

    It's supposed to be attached to the firewall near the battery.  It looks like the one that goes to the positive terminal.  They sit close to each other and sometimes get switched by accident.

    You don't show the ground test in your list.  Testing grounds is probably the most commonly overlooked test for automotive electrical problems.

    Ahh, ok.  There was a random wire that was grounded to the firewall near the battery.  Had no idea what it was for, but cleaned it up anyway.

    Can you elaborate on the ground test? Test 1-8 in the FSM passed and seemed to relate to the grounds to the ECU wiring harness.  But I'd love to have a more thorough test of the overall grounding.  Is there a detailed test in the FSM?

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    Ah yeah, I did those.  It just didn't fit in my screenshot.  All of 1-8 tests passed with basically no resistance.

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    We're in the very common troubleshooting loop of "I already did that".  You're about at the point where you just have to understand how the system works.  The first few pages of the engine fuel chapter tell you what is supposed to happen.  The injectors open when the power is grounded, they stay open for a length of time that is determined by things like temperature and how far open the AFM vane is, etc.

    Once you start thinking that way you'll have new ideas.  Seems like you've done a bunch already that you haven't described, and haven't done some of the things that have been suggested, like confirming power to the injectors during starting.  Good luck.

     

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    27 minutes ago, S30Grit said:

    Thanks siteunseen.  Hard to tell if there are multiple wires going to that firewall ground, I know I only had the one black wire.  

    I'm sure it's just one and I've seen many that have melted the insulation off that wire.

    Sand the firewall too under there.

    Edited by siteunseen

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    Good deal, when I took it off the firewall, it actually looked like the area had gotten some attention recently, but hit it with a wire brush anyway.

    And yes, it is a troubleshooting loop at times, but the forums have been very helpful to bounce ideas off of.  With all the bad connections/grounds I've encountered already.  It seems like I could be down this path for a while.

    The car has a dead-man switch installed in the cabin and wired to nothing in the engine bay right now.  I'm tempted to wire this up to the CSV so I can manually trigger it instead of using starting fluid lol...

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    It's a little late to be doing this, but I'd like to drop back a little... We've all been treating your cold start difficulties as a lack of fuel situation, and I would like to investigate that a little more.

    You've mentioned a couple times that the injectors don't seem to be firing when you're trying to start the cold car. Can you provide some more details as to how are you coming to that conclusion?

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    I got money on the IGN switch, I know its new, but was it checked before installing.

    let me summarize what I think is the situtation

    Runs fine if started with starting fluid. So all systems needed for operation work fine BUT for START

    functions of START

    FUEL pump ON

    IGN relay ON (ECU power and pump)

    CSV ON (if cold, but its not cold so OFF in this case)

    SPARK ON.

    Starter ON

    All of these are controlled by that START selection on the key switch. My guess is one of those is not happening hence the need to monitor them all while someone cranks it to isolate. monitor fuel pressure, monitor spark, monitor injectors (clicking).

     

     

     

     

    Edited by Dave WM

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    2 hours ago, Captain Obvious said:

    It's a little late to be doing this, but I'd like to drop back a little... We've all been treating your cold start difficulties as a lack of fuel situation, and I would like to investigate that a little more.

    You've mentioned a couple times that the injectors don't seem to be firing when you're trying to start the cold car. Can you provide some more details as to how are you coming to that conclusion?

    Yeah, I noticed people were trending that way too.  It could be related to fuel, but as far as I can tell fuel is completely fine as described earlier.

    The mechanic used an in-line noid light (allows injector to still be connected up while testing) for the injectors and there was no signal when trying to start the car.  Similarly, I myself have connected an LED to the injector harness (not in-line) and found similar results, by unplugging the injector harness and plugging an LED to both terminals.  No pulse while cranking.  While rotating the key through the ignition, I can get a SUPER short flicker of the LED, but definitely way too short to be consider a "pulse" IMO (hint hint what Dave WM said has a good chance I think).  During cranking, I'm expecting a short and consistent pulse of the LED, but there is simply nothing.  As @Zed Head suggested, it is valuable to know if the injectors are receiving the constant +12v during starting.  If no constant +12v during cranking, then the issue could maybe be on the power-side of the injector (maybe drop resistors).  If there is constant +12v to ground at the harness during cranking, then the issue is likely on the grounding side of the EFI circuit or ECU... I'll be testing that next time I have time.

    My thoughts are that at this point, the most common suspects are: Ignition related, drop resistors, or some other EFI wiring/ground problem.  Also, I need to run tests 3-1 through 3-3 according to FSM.  Some ignition and EFI tests should find the culprit, hopefully this weekend.  Thoughts on easiest test to run with most useful results?  I figure thoroughly testing the ignition system AND it's wiring may be a pain.

    image.png

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    2 hours ago, Dave WM said:

    I got money on the IGN switch, I know its new, but was it checked before installing.

     

    I'm right there with ya Dave WM!  The guy I bought it from installed the new Ignition Assembly, but I think it's likely either not wired up perfectly, or a ground to the IGN or something isn't strong.  Working alone makes it somewhat of a pain to test the stuff... but hopefully I can confirm some basic ignition wiring and the switch itself soon.

    Edited by S30Grit

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    I'm wondering if the ECU isn't getting a good "the engine is turning now - you can start firing the injectors" signal when it's cold. Does your Tach show RPM while cranking? Also, have you checked the ECU plug and socket connections for oxidation. (Going back to the "90% of the problems I've found in these old EFI systems have to do with wiring and connectors"...)

    Edited by cgsheen1

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    18 minutes ago, cgsheen1 said:

    I'm wondering if the ECU isn't getting a good "the engine is turning now - you can start firing the injectors" signal when it's cold. Does your Tach show RPM while cranking?

    That's a good point, I'm not sure off the top of my head what the tach is doing, I'll have to get back to you. I think this is supposed to come into the ECU as the "Ignition trigger coil signal"

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    You could always try to hot wire the car to eliminate the switch as a problem

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    17 hours ago, Patcon said:

    You could always try to hot wire the car to eliminate the switch as a problem

    I did look at the ignition wiring last night, might give it a go

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    S30 Grit, 

    I'm with Dave WM. I had the same problem your having and it turned out to be the ign switch. Perform the testing , out of the car, as Dave's   

    video mentioned earlier and pay close attention to the resistance in the start position. Mine was OK on several tries in the start position,

    but not consistent. 

     

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    9 minutes ago, zclocks said:

    I'm with Dave WM. I had the same problem your having and it turned out to be the ign switch. Perform the testing , out of the car, as Dave's   

    video mentioned earlier and pay close attention to the resistance in the start position. Mine was OK on several tries in the start position,

    but not consistent. 

    Good thinking.  The guy i bought it from left the old ignition switch in the car and I tested it last night.  It had similar behavior to what's shown in @Dave WM's video.  There seemed to be a sweet spot when turning through the "start" range where everything behaved as it should, but outside of that sweet spot, resistance was either infinite or variable.

    Has anyone confirmed that test with a new/working ignition switch?  Mostly curious if I should expect the entire range/area when turning past "On" and through "Start" to have no resistance for the marked pins in the FSM? Or is it normal for there to be a slightly more narrow "sweet spot"?

    Either way, my old ignition switch has a pretty big and consistent "sweet spot" which seems like it should have been usable...  I haven't checked the new unit that installed in the car now, but I will hopefully this weekend..

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    S30 Grit 

    Yep, I tested my new switch and it was a solid connection through the complete range of the "Start" portion of the switch. No sweet spot just continunity.

    Ron

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    40 minutes ago, zclocks said:

    Yep, I tested my new switch and it was a solid connection through the complete range of the "Start" portion of the switch. No sweet spot just continunity.

     

    Awesome, thank you Ron

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    Pop for the NISSAN OE switch, about 40$ shipped IIRC, not the aftermarket one, they go for about 25$ shipped, not worth the savings.

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    welp ran through a few more things today.  I did mess around with the ignition switch, but I'm not sure it's the cause of my problems for two reasons.  The starter pin is is not continuous across the whole of the rotation through "Start", but it's consistently continuous towards the end of rotation, like the last 20% .  The ignition pin is working as expected, through "On" and all of rotation through "Start".

    Either way, technically this should still work if I understand things correctly.  Even if I have to turn the key to the final 20% on Start, both Ignition and Starter lines are receiving battery power (as they consistently did in several repeated tests), the dang thing should start, right?  The only other variable is that testing the switch wasn't done under load.

    ^^ So that's the first reason I think it may not be the main cause.  The 2nd reason is that while trying to chase down a short in my Hazards circuit (ughhh), I came across a beautiful connector shown in the image, look at those colors (passenger side footwell under carpet). The one wire just fell right out of the connector... I haven't looked up what that specific harness is even for yet, but I'm expecting this and some other wiring fun to be related to the starting issue.  Most of the other harnesses I've inspected are no where near this bad thankfully.  But this isn't even mentioning some other wiring nightmares from what appears to be a 12 year old getting lose in this car hopped up on mountain dew and holding a pair of wire snips..

    I may start another thread on some wiring questions, but I'm shocked the car even runs on starting fluid right now.  I found wires intentionally cut (1 major power wire it looks like), a couple harnesses not plugged in, and not to mention there's probably more corrosion lurking, even though I've been tackling it head on.. Rewiring the cut wires worries me the most, because I have no idea where they originally went or WHY they were cut 🤦‍♂️

    IMG_20191026_144913.jpg

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