# new to ZX's



## my86z (Jun 19, 2006)

Ok, first I'd like that thank you all for the opportunity to become a member of a forum such as this.

Second, I just purchased a 86 300ZX at what I believe is an awesome price. It's a non-turbo with automatic. However, I have some concern about the motor. When I checked out the car, it has an overheading problem. The upper radiator hose, to the thermostat housing, didn't get hot. I'm assuming that the thermostat is stuck. No big deal on this problem. The other issue, of major concern, is that when the motor is revved in park, it will stumble as the rpms get to about 3k and full throttle as if it wants to die out. Is this normal? Or do I have underlying issues with a sensor or fuel systems? Third issue I've noticed is that there's alot of crud on the inside of the oil fill cap. Is this just a sign of neglect or was it run too hot for too long?

Any assistance is greatly appreciated.

Wink


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## Spongerider (Nov 18, 2002)

my86z said:


> Ok, first I'd like that thank you all for the opportunity to become a member of a forum such as this.
> 
> Second, I just purchased a 86 300ZX at what I believe is an awesome price. It's a non-turbo with automatic. However, I have some concern about the motor. When I checked out the car, it has an overheading problem. The upper radiator hose, to the thermostat housing, didn't get hot. I'm assuming that the thermostat is stuck. No big deal on this problem. The other issue, of major concern, is that when the motor is revved in park, it will stumble as the rpms get to about 3k and full throttle as if it wants to die out. Is this normal? Or do I have underlying issues with a sensor or fuel systems? Third issue I've noticed is that there's alot of crud on the inside of the oil fill cap. Is this just a sign of neglect or was it run too hot for too long?
> 
> ...


1)HOw long did you let the motor run before you touched the upper rad hose? You should go for a good drive and then test the hose I bet it will be hot. BTW when a thermostat gets stuck you have over heating issues.

2. Check your spark plugs. If the plugs look fine then check and replace the fuel components.

3. Start running some 20w-50 synthetic oil to clean up your engine.


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## my86z (Jun 19, 2006)

The motor was run until the temp gauge started to read right before the needle got the the H on the gauge. I touched the upper radiator hose at that time, and it was cold to touch. Wich tells me the thermostat is not opening properly.

I'll look at the plugs when I pull them out ( I'm planning on a complete tune up this week on her). And if that clears up the stumble, I'll be very happy.

Thanks for the suggestion on the oil. I'll change it to the synth right away and see if that cleans it up fairly well.

Thanks,

Wink


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## depswha (Feb 8, 2006)

Hello everyone,
I just bought a 84 300zx and I have some questions. the car starts and runs but nothing works on the dash. not the digital display not the a/c unit, wipers, lights nothing. its like I am getting no power to the dash at all. at first I thought the power box was bad for the dash but it does not run everything. right now I have everything pulled out so I could look at the wiring harness and it seems to be good and intact. the fuss box is only getting power to about 4 fusses in the box. I will have a lot of questions on this car but I want to start with this. 
any help anyone can give I would like to thank.


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## my86z (Jun 19, 2006)

Ok, I got the t-stat replaced, and changed the oil to synth 20w-50. So, the overheating problem is fixed. But I have one more problem that seems to be eluding me. Engine idles fine. But when you press on the "go" pedal and hold it, it will go to about 2500 and die, then catch again and go to 2500 and die. Unfortunately I don't have a repair manual yet (will definately get one very soon). But in the mean time, anyone else ever come across this problem? Could this be a bad MAF?


edit: Ok, Ok. You don't have to flame me just yet. I did alittle research. So far I've come to the conclusion that it could be the MAF, TPS, or the ECU. I guess I need to get that maintainence manual in order to know how to check these darn codes.



Wink


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## Spongerider (Nov 18, 2002)

my86z said:


> Ok, I got the t-stat replaced, and changed the oil to synth 20w-50. So, the overheating problem is fixed. But I have one more problem that seems to be eluding me. Engine idles fine. But when you press on the "go" pedal and hold it, it will go to about 2500 and die, then catch again and go to 2500 and die. Unfortunately I don't have a repair manual yet (will definately get one very soon). But in the mean time, anyone else ever come across this problem? Could this be a bad MAF?
> 
> 
> edit: Ok, Ok. You don't have to flame me just yet. I did alittle research. So far I've come to the conclusion that it could be the MAF, TPS, or the ECU. I guess I need to get that maintainence manual in order to know how to check these darn codes.
> ...


Did you replace your spark plugs, fuel filter, fuel dampner, & fuel regulator? I don't think it's your MAF they rarely go bad.


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## Madmaxfl (Oct 22, 2005)

Spongerider said:


> Did you replace your spark plugs, fuel filter, fuel dampner, & fuel regulator? I don't think it's your MAF they rarely go bad.


You really need to run the codes from the ECU to see what is going on. It is not hard to do, just get a Haynes manual now you will need it with these cars. it does sound like a MAS but check the codes to be sure. The MAS can go bad from somethig being sucked in to the intake like a bug and also from excess oil on oiled filters like K&N's less is always better.

I have seen a MAS on a hardbody PU that had a roach burned on the sensor wire. When delicately cleaned off the truck ran like a champ.


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## my86z (Jun 19, 2006)

Well, my codes tell me that there are problems with the cylinder head temp sensor circuit, the Idle switch circuit, And I got a code 31.......

I don't like the look of that last code. It's basically telling me one of my load sensor circuits are inop, or the ecu is faulty. So, I guess I'm sourcing out for another ecu now.


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## Madmaxfl (Oct 22, 2005)

my86z said:


> Well, my codes tell me that there are problems with the cylinder head temp sensor circuit, the Idle switch circuit, And I got a code 31.......
> 
> I don't like the look of that last code. It's basically telling me one of my load sensor circuits are inop, or the ecu is faulty. So, I guess I'm sourcing out for another ecu now.



The Cyl head Temp Sensor can cause the others to come up also. Before going with a new ECU I would change the CHTS. Not all that easy a task. if you can find a cheap ECU that matches you could swap it and see if you run the same codes. I have been able to pick up ECU's for my 85 NA for $40 - $50


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## my86z (Jun 19, 2006)

Looks like the CHTS is a dealer only part. I don't see them listed in my local parts stores. Other than the dealer, where else can I locate one of these?


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## Madmaxfl (Oct 22, 2005)

my86z said:


> Looks like the CHTS is a dealer only part. I don't see them listed in my local parts stores. Other than the dealer, where else can I locate one of these?


When replacing sensors like the CHTS the dealer is the best place for a replacement. I do not know for sure but I would think there are cheaper aftermarket replacements. Just keep checking parts stores.


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## armedfrbattle (Jun 26, 2006)

how can i run the codes from my ECU i have the haynes mannual


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## Madmaxfl (Oct 22, 2005)

armedfrbattle said:


> how can i run the codes from my ECU i have the haynes mannual


Read the book. You have to pull the kick panel from the passenger side to reveal the ECU and then take out the two screws that hold it in place. There is a screw on top that you have to turn about 180 degrees, turn on the ignition and then count the red light flashes to get the codes. normally the codse numbers are on the ECU. This is a brief overview but you have to read the manual and it will give you a step by step.


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## my86z (Jun 19, 2006)

IT's ALIVE!!!!!!!!!!

Another Z owner loaned me a MAF and ECU to help me further troubleshoot my issues. Well, today I swapped out the MAF. It fired right up and maintained a "decent" idle. It idles a bit low, and wants to stall. But I'll have that fixed today when I adjust the ignition timing and idle adjustment. I'm just happy it's running again.

Thanks for all of your help.


Wink


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