Car takes long to start in 16 degree weather

[FreddyZ78]

Ive got a 78 280z. What can I do to help my car start faster in cold weather? Right now its getting to about 15-20 degrees and it'll take almost 5 minutes of cranking to get it to start. Any suggestions on what I can do?

[miky360]

That's odd. We're at -1*C here in Toronto and I have no issues starting my car. I daily it actually lol

Any noises you're hearing?

[9rider]

I cranked about 3 times most when it hit 25F here in Bishop last couple weeks. Check your cold start valve ( injector) and cold start air by pass. 

[Pharaohabq]

Exactly, the Cold start and Thermotime can really make starting in the cold difficult. These are detailed in the 280Z EFI Addendum here: L28 EFI Addendum  Basically, the Cold start acts like a Choke, putting more fuel into the engine when cold, the Thermotime, depending on temperature will open the cold start injector of a short period then close it so keep the car from flooding. Now if it's not opening the Cold start injector, then it would make it difficult to start, just as it would if it was keeping that injector open too long and flooding the engine.  The Cold start injector only operates while the starter is cranking. I believe the Thermotime opens the injector at ~45^o and only keeps it open for about 12 seconds before it heats up and closes the ColdStart injector again. There are test procedures for the Thermotime, but if you have a Z junkyard, you could just swap it out. I'm not sure if it's still available from Nissan. Usually that Cold start injector doesn't go bad, it's almost always the Thermotime.  The Thermotime is mounted on the thermostat housing, see the manual.

 

Phar

[NewZed]

Any suggestions on what I can do?

Give it a tune-up.  But fix your vacuum leaks first, lean mixture plus cold = hard-starting.

 

http://forums.hybridz.org/topic/115703-idle-drop-and-popping-sounds-from-intake/?do=findComment&comment=1084488

[Pharaohabq]

I was reading a bit more about the Thermotime.  IT is just a switch that opens after heating for 15 seconds.  so conceivably you could pull loose the wires and ground the one going to the Cold Start then when you try to start the car the Cold start injector would run. BUT if you crank it longer than say 15 seconds, you could flood the engine.  But if it started right up, you'd know for sure it's your Thermotime. That's not the recommended test in the manual, but if you're out freezing and trying to start the thing then it might be worth trying.  If you have a meter the pin to ground is the line from the CS injector.  If you ground the wrong one it is possible you could burn something up. So use caution, and maybe a 10A fuse.  Injectors on the L28 open when grounded.  it looks like it's connector 46. the male spade from the CS injector.   Anyone ever try this?

 

[HowlerMonkey]

These engines won't start that cold without the cold start injector working.

 

I used to carry around a can of carb cleaner and would pull off a vacuum hose and give it just a little shot and the car would start right up while no amount of cranking would start it otherwise.....until warm.

 

Thermo time switch makes the cold start injector work for those few seconds you need it.

Edited November 21, 2013 by HowlerMonkey

[Tony D]

The cold start injector just blasts fuel into the plenum to get the engine to fire. 

After that, cold running is handled by a map in the ECU based on input from the coolant temp sensor. 

 

Cold Start Injector floods more engine than it starts, sometimes.... I swear!

 

Ether is a nice way to get it fired. Squirt a shot in the air cleaner, touch the throttle slightly and try a crank. Once they fire, then the rest is easy.

 

This could be some many other things as well... Excessive Cranking almost ALWAYS wet fouls the plugs in a Z from too much fuel from the Cold Start Valve. If your ignition is up to snuff, and the cold starter does what it should, and you have no vacuum leaks and a proper valve adjustment it will fire and run EVERY TIME with less than 10 seconds of cranking.

 

If it doesn't, you have work to do.

[Chris Duncan]

I was reading a bit more about the Thermotime.  IT is just a switch that opens after heating for 15 seconds.

 

Actually it's a bi-metal switch that is controlled by two different things. First the temp of the coolant, 2nd the heating element.

 

So 15 seconds is the longest it can stay open. Depending on engine temp it can be open before you even start the engine.

Edited November 30, 2013 by Chris Duncan

[9rider]

You can check your MAF. My car acting weird couple days ago. It idles fine, rev up fine, but as soon as I release gas pedal to shift to another gear ( mainly 1 - 2 nd) it would stalled and stop. 

I checked it today and it appear to be MAF. Key on , I tried to move the flap inside the MAF, I can see my FP gauge jumped up and down. However, after couple moves, it didn't send any signal at all to the pump, hence the FPG stay the same. I lightly tapped the MAF and it worked for a couple times and stop and work. 

I will take the MAF out to check out tomorrow.

Hope this is some information for guys have same issue.

Have a good weekend Holiday guys and gals. Be safe.

[FreddyZ78]

I fixed the vacuum leaks car starts up right away now. Going to be getting a valve adjustment tomorrow morning. Thanks for the help guys!