280Z Difficulty starting

[Zed Head]

The CSV action is determined by the thermotime switch.  Nothing to do with the coolant temperature sensor.  The thermotime switch has a temperature actuated relay inside, and its own heater (actually a pretty sophisticated device considering what it looks like).  It can also be tested.

[Marios280Z]

The CSV action is determined by the thermotime switch.  Nothing to do with the coolant temperature sensor.  The thermotime switch has a temperature actuated relay inside, and its own heater (actually a pretty sophisticated device considering what it looks like).  It can also be tested.

Yes...Had to read about it again to get it straight in my head. It completes the circuit between the ignition SATRT signal, the CSV and ground when the engine is cold. When warm, thermotime switch is not pulled to ground and therefore CSV power circuit is open.  So short of installing resistor on it as H-m indicated in post #69, there is not much I could do to test it's operation (unless it will get cold soon). I have tested its resistance per FSM and it was good.

 

I will also test with CSV disconnected all together as mentioned in earlier posts.

[Marios280Z]

Kind of funny - I misinterpreted the chart again.  It actually shows CSV enrichment as separate from Start enrichment.  So Start enrichment is probably always there hot or cold, maybe to varying levels depending on temperature.  Since the system is designed to be started with the throttle closed, idle switch actuated, I wouldn't be surprised if your idle switch is dirty or maladjusted and part of the problem.  Also wouldn't be surprised if ti was fine and not your problem.

I'm assuming that idle switch is inside the Throttle Position Sensor, correct?

[rcb280z]

A little late reading this post but my 77 starts the same way as far as the 2 to 3 times cranking goes. Used to hear a loud click sound when the CSV was working but have not lately. So I removed the thermo time switch and stuck it in the freezer for about ten minutes, put it back in the housing and my Z started right away. No 2 to 3 attempts at it. Also could hear that loud click letting me know it was working. I think you should test your thermo time system. 

I haven't had time to troubleshoot mine yet. Just did that quick freezer test. It's the only time I have issues with starting my Z, when it's cold as in sitting for several hours over night.

Once started it runs fine right? It's what mine does. When it started this 3 months ago I thought I was having fuel pressure issues but was not. Worth looking at. Just my 2 cents.

 

Just looked at the videos again and its almost identical to mine. Doesn't mean it has the same problem as mine but again I think its worth looking at.

[Marios280Z]

rcb280z, thanks for sharing your experience. It does sound exactly like your issue...Did you have to drain coolant before you pulled out thermtime switch?

 

I have mixed feeling about this cold start system. A lot of people say that they just remove it all together and don't have problems starting. I also have tested it at the ECU as well as at the sensor itself. The results were showing no issue, but perhaps I was making wrong measurements.  I will revisit the whole system once more.

[rcb280z]

Just stuff a few rags under it and be fast about it. You will loose a little coolant. Leave your rad cap in place, it will help. The less air the system intakes the less coolant you'll loose. There is a brass washer so be careful not to drop it.

 

There is nothing better than the cold start system when it is functioning properly. Trouble shoot and fix the problem and you'll be happy. Still keep in mind that just because we have similar issues it doesn't mean this is your problem. Check everything. There are very knowledgeable members so take what they recommend seriously. 

[Captain Obvious]

I'm one of the people who has disabled their cold start system. I removed the connectors to both my CSV and my thermotime switch a couple years ago and don't really miss it.

 

In the cooler months, I do notice a slightly longer crank time the first crank of the day, but it's not like yours. And in the warmer months, I don't notice any change at all which makes sense based on the temp at which the thermotime is supposed to open. At your current ambient temps, your thermotime should be open 24-7 as well.

 

I mean, I completely understand why rcb280z is suggesting the cold start system stuff... It sure looks and sounds like it wants more fuel. But if it's 85 ambient, you shouldn't be expecting the CSV to actuate anyway. My engine doesn't need any additional fuel at 85 ambient and it doesn't take me 2-3 tries to get mine to start.

 

You've got something else going on...

 

Have you checked for vacuum leaks? Search here at the site for "yogurt cup". Have you put a vacuum gauge on it when it's running? Here's some common areas of concern:

 

Hole in your rubber PCV tube?
Leaking intake manifold?

Poor seal around your dip stick or oil fill cap?
Cracks in your AFM boots?

Malfunctioning CARB can valve?
 

[rcb280z]

Agreed, if its that warm the cold start doesn't actuate. Forgot its that warm there. 

[Captain Obvious]

Yeah, in theory it should be too warm for the CSV, but you're right, it certainly seems like it wants more fuel.

[Marios280Z]

Had no time to do much testing yesterday, but this morning I disconnected CSV all together as it was suggested to me few posts back, just to verify that the CSV wasn't actually flooding the engine. It did not help. Took me 4 times cranking before the engine fully engaged (same procedures for starting: primed the fuel pressure couple of times, car was in the garage over night).  

[Captain Obvious]

Good. One less thing to worry about. If I were you, I would just leave it disconnected for now. If it still started the exact same way with it disconnected, it's not like it's doing anything good for you anyway.

 

Think about the vacuum leaks... Maybe you split a brittle boot or hose while you were doing all the other work to the car. For all you know, when you were in there wrestling your old stuck distributor cap off, you pushed the wrong way on one of your AFM boots and open up a crevice. You have a vacuum gauge?

 

And as another shotgun... All of this started after you did a bunch of ignition work, right? I know it's a long shot, but did you keep the old ignition parts? If all else fails, you could toss the old stuff back on just to see what happens.

 

[Marios280Z]

Good. One less thing to worry about. If I were you, I would just leave it disconnected for now. If it still started the exact same way with it disconnected, it's not like it's doing anything good for you anyway.

 

Think about the vacuum leaks... Maybe you split a brittle boot or hose while you were doing all the other work to the car. For all you know, when you were in there wrestling your old stuck distributor cap off, you pushed the wrong way on one of your AFM boots and open up a crevice. You have a vacuum gauge?

 

And as another shotgun... All of this started after you did a bunch of ignition work, right? I know it's a long shot, but did you keep the old ignition parts? If all else fails, you could toss the old stuff back on just to see what happens.

So, as far as I can recall  the ONLY think I did under the hood before the starting issue showed up was fuel filter replacement. I did change engine, tranny, and rear diff oils first before I started to work in the engine bay, but that shouldn't have any effect on my starting issue. I changed the ignition coil and distributor cap and rotor AFTER I already have been experiencing starting difficulties.

 

I have been thinking about the vacuum leaks. I don't have a vacuum gauge. One method I have heard about is to use carb cleaner or starting fluid and spray small amounts around hose fittings and suspected areas. Of course be careful and do it when the engine is cold to avoid possible fire. If the engine suddenly revs up it means it sucked in the fluid and that is where the leak is. Is that acceptable procedure?

Edited August 12, 2015 by Marios280Z