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1983 280zxt runs awful till fully warmed up


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#1 k204drek

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Posted 10 December 2012 - 05:23 PM

OK as the title says my 1983 280zx turbo runs awful until it is fully warmed up.. It also will not idle it just dies and then you crank it back up and it runs for like a second then dies but when you finally get it idle When you try and give it any gas it backfires through the intake and studders. When it gets warmed up it runs alright it still studders a little and backfires sometime but runs good enough to be driven. Also if the rpms go anything above 1k my fuel, door, charge, and another light stay on and my heater fan will come on sometimes but then it cuts off. With it idling and the heat on it idles at like 1.5k with the fan on and the selector in the air position (although i dont have an air belt) it will idle up to like 2k. I have had this thing for about 5 months and fiddled with it here and there and nothing i do makes a difference.



#2 evildky

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Posted 11 December 2012 - 01:21 PM

Sounds like you have a couple of issues goign on. Not wanting to start up is usually the CHTS, when the car is cold try unplugging the chts and see if it starts better, if so you have a bad chts. Once the car is runnign right the idle issues will hopefully follow. The lights ont he dash are likely a bad circuit inside your alternator which requires the alternator be replaced.


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#3 k204drek

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Posted 11 December 2012 - 06:53 PM

I have tried unplugging the CHTS and the car wont even crank. Ive been researching and is it possible that it could be the Air Regulator? Ill replace the alternator.



#4 stravi757

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Posted 12 December 2012 - 10:57 AM

It is unlikely that you will ever get the engine to start cold with the chts unplugged. A bad chts Sensor could very easily be bad causing problems for starting and drivability, not uncommon. A new sensor is only about $30, I would start by replacing that. Have you checked for vacuum leaks? Tested your alternator? No point in replacing it if its in good working order. Its tough to say what the problem is with the info you gave us. It could be alot of things. A bad air regulator may cause you stuttering startup if its pretty cold outside, but problem should reside after 30 seconds or so by holding the throttle down slightly. doesn't sound like this is your problem. Please download the FSM and start reading through there. Its simpler that you think and it will more than likely answer some of your questions and help you understand how the efi works.



#5 k204drek

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Posted 12 December 2012 - 01:39 PM

No vaccuum leaks i fixed all those when i got the car. ill try and get to the parts store and get a chts. Iv downloaded the FSM been threw the fuel injection part a few times and researched countless hours tryieng to figure out whats wrong with it. Its my only car right now.



#6 k204drek

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Posted 12 December 2012 - 06:46 PM

Well i unplugged the chts and it fired right up it runs perfect with it unplugged but when i plug it back up it goes back to running like crap i drove it about 30 miles with it unplugged it has plenty of power and runs like a scalded dog. i went to oreilleys and the sold me what they said was a chts for 15 bucks so we will find out tommorow if its right. I really appreciate all the help.



#7 k204drek

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Posted 13 December 2012 - 09:20 AM

I replaced the chts and it runs like crap still but runs perfect with it unplugged.

#8 evildky

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Posted 13 December 2012 - 12:22 PM

If the car runs well with the chts unplugged and it's nto really cold out, you have a problem. With the CHTS unplugged the ecu should be dumping mass amounts of fuel, could be a bad ecu. Possibley a weak fuel pump or bad fpr.


"if I had all the money I ever spent on cars...I'd spend it all on cars"
12.610 @113.52 mph, 299.3whp 305 lbft TQ
Warning! if you take this or any post too seriously, your head will explode, your dog will run away and your car will break!
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#9 k204drek

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Posted 13 December 2012 - 04:47 PM

its about 30 degrees out when i first crank it then it sits at school for 8 hours and i crank it with it unplugged. But if i stop somewhere for less than 2 hours it wont crank with it unplugged. It doesnt run rich or anything. But while it was running i tried jumping the chts plug and it started running like crap so im thinking the auto store just gave what they had they called it a coolant temperature sensor and it looks different than the CHTS pictures ive seen but the CHTS i pulled out looked just like the one i put in. With the new CHTS plugged in it will crank and idle cold but if you try and rev it before it warms up it dies and wont crank without it being unplugged it also stutters and pops and coughs. WHen i going down my long driveway this morning it died and wouldnt crank back because the fuel pump would not come on but after about 10 minutes it cranked it and i drove 20 minutes without any trouble. It runs perfect with it unplugged. COuld my 02 sensor be bad as well?



#10 NewZed

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Posted 13 December 2012 - 05:05 PM

Testing the CHTS is super simple, it's not even hard to reach like on the thermostat housing mounting position the 280Z use.  It's right there.  There's a chart of resistance versus temperature in the FSM. There's a lot of other info in there too.  At least you'll know if you have the right one.

Attached Files


Edited by NewZed, 13 December 2012 - 05:05 PM.


#11 k204drek

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Posted 13 December 2012 - 06:15 PM

Ok at 76 degrees F i have 1.8k ohms on the old sensor havent tested the new one yet.


Edited by k204drek, 13 December 2012 - 06:37 PM.


#12 NewZed

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Posted 13 December 2012 - 06:32 PM

The two metal prongs that you see when you unplug it.  Doesn't matter which probe is on which side.



#13 k204drek

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Posted 13 December 2012 - 07:01 PM

Is it possible to replace the CHTS with a potentiometer? 

This is the sensor i have http://nissan.autopa...ure/1293742.jpg

 

Ok at 76 degrees F i have 1.8k ohms on the old sensor havent tested the new one yet.



#14 motomanmike

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Posted 14 December 2012 - 08:26 AM

That value seems pretty close with the chart. How is it running now? I know you aren't running MS but on the DIY autotune site they have an FAQ on explaining how to test the values of a sensor such as that one, fill a bowl with icy water with ice cubes, let the sensor sit in it and test, then room temperature water, then almost boiling water, noting the values. That sensor might be off at a high or low range. Its cheap enough to test it :)

Edited by motomanmike, 14 December 2012 - 08:39 AM.

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#15 k204drek

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Posted 14 December 2012 - 08:48 AM

It runs perfect right now with the CHTS unplugged. I have to get out open the hood plug the CHTS up then cranl it unplug it and go if its warmed up if its cold it cranks right up unplugged.




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