New to z31 need help with strange hesitation - Page 2 - Nissan : Datsun ZCar forum :Nissan Z Forum: 240Z to 370Z
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post #11 of 46 (permalink) Old 09-17-2014, 06:06 PM
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codes are useless. change the chts. speed sensor doesn't affect anything. throttle switch either except gas mileage because it leans out the engine when sitting at a light.

86T, 350 Nismo 08 (#1415) gone but fondly remembered 81T, 83T, 83, 85T, 86T, 96TT
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post #12 of 46 (permalink) Old 09-17-2014, 06:26 PM
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Even if you want to ignore the codes and any sort of problem-solving method, you should still measure the CHTS resistance at the ECU. Then you'll know if you're wasting your time and money on somebody else's wild guess.

Easy to throw out guesses like it's a game. Kind of fun too. Entertainment.
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post #13 of 46 (permalink) Old 09-17-2014, 08:37 PM Thread Starter
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Well I don't know all this stuff .... And after the ecu goesed to closed loop it stops throwing that.code and just throws 13. And 24 makes no sense my care is a manual . So give up?
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post #14 of 46 (permalink) Old 09-17-2014, 09:18 PM
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Originally Posted by drdamm21 View Post
hrowing codes when key on 23 and 31 when car is running it shows 23,14.
Well now, it looks we've gone in a big circle, and ended up where rogerz might be both right and wrong at the same time, and you have a problem with numbers, either remembering them or typing them on to a page. You never mentioned 13, which is the CHTS code. rogerz might be right about the CHTS. But if he is right, then he's wrong about the worth of the code.

And manual transmissions do have a "neutral", which could be the code 24.

Anyway, good luck with it. You can either change the CHTS and hope, or fiddle with the plug on the CHTS and hope, or learn how to use a meter. Looks like you're closer than you were.
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post #15 of 46 (permalink) Old 09-17-2014, 10:37 PM Thread Starter
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Well now, it looks we've gone in a big circle, and ended up where rogerz might be both right and wrong at the same time, and you have a problem with numbers, either remembering them or typing them on to a page. You never mentioned 13, which is the CHTS code. rogerz might be right about the CHTS. But if he is right, then he's wrong about the worth of the code.

And manual transmissions do have a "neutral", which could be the code 24.

Anyway, good luck with it. You can either change the CHTS and hope, or fiddle with the plug on the CHTS and hope, or learn how to use a meter. Looks like you're closer than you were.
I have a meter but makes no sense to check or change the chts if it's not throwing a code? This sucks ask qs on what I remember being a great site and now 10 years later and get a puzzle.
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post #16 of 46 (permalink) Old 09-17-2014, 10:49 PM
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Well I don't know all this stuff .... And after the ecu goesed to closed loop it stops throwing that.code and just throws 13. And 24 makes no sense my care is a manual . So give up?
Seems like you're just not putting 2 and 2 together. 13 is the CHTS code. It's shown in the EFEC chapter of the 1985 FSM. So what's the puzzle? The code, designed to show you where a problem is, is showing a problem with the CHTS. This is the same thing that rogerz is certain is the problem.

The FSM says that if you see code 13 to go to page EFEC-56. Page EFEC-56 shows you what pins to put the meter probes on to measure resistance. It also shows you resistance numbers that will tell you if the CHTS is in-spec.

I'm not seeing a puzzle. Do you have a copy of the 1985 FSM?

http://www.nicoclub.com/FSM/

If it's too hard, any shop can read the codes, do the tests, replace the CHTS and fix other problems, and charge you a couple hundred dollars. Or you can go buy a CHTS and swap it in. Maybe you'll get lucky.

I'm just offering a path to knowing what's wrong before buying parts. Doesn't have to be followed.
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post #17 of 46 (permalink) Old 09-17-2014, 10:51 PM
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well I have had three z31 plus an s130. all improved their driveability when I put in a new chts. Do what you like. codes are pretty well useless with a 20 plus year car that has had god only knows what done to it. If you really want to spend the time testing a $30 part then you need to do a complete resistance curve by throwing it in an oil bath with an ohmeter attached and a thermometer. Heat the oil and note the ohms resistance change vs temp increases. cold resistance only tells you what is happening at that temp. but the chts is a dynamic unit. by the way what sort of vom do you have. An autoranging Fluke will cause you more heartache than a $20 analog from Harbor Freight unless you have a good deal of experience using one. See Tony''s rant on that subject. You don't seem to have much experience with electrical circuits from your posts. Depending on throwing a code is the road to remorse with a z31. as pdx said you are getting a chts code.

86T, 350 Nismo 08 (#1415) gone but fondly remembered 81T, 83T, 83, 85T, 86T, 96TT

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post #18 of 46 (permalink) Old 09-17-2014, 11:14 PM
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Ya gotta pick one side rogerz. You can't use the code to suggest changing the CHTS but also say codes are worthless.

Anyway, if you don't know how to use a meter, the FSM is kind of worthless. So go ahead and swap that CHTS.

For the record though, you only need a couple of points to check the CHTS. If they're on the curve the rest will be too. Chart on EFEC-57.
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post #19 of 46 (permalink) Old 09-18-2014, 10:31 AM
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The throttle valve switch, from what I remember, just kicks the throttle up a bit to warm the car up, and drops it down once it's warm. Unless its really cold out, I doubt that switch would make a difference. You could probably unplug it and not notice a difference. You unplug it to adjust base idle.

My car has a similar issue, where it hesitates and bogs a bit under acceleration but only for the first few blocks of my drive, and goes away even before the car warms up to normal operating temp. My best guess is it's a slight leak in the intake manifold or somewhere that expands and seals after a few seconds of heat. I've learned to ignore it.

1984 300ZX N/A Automatic
130,000 Miles
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post #20 of 46 (permalink) Old 09-18-2014, 10:33 AM
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For the record I replaced my CHTS and had little to no effect on that issue. It did however help my extended cranking to start the car when cold.

1984 300ZX N/A Automatic
130,000 Miles
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