uranus

1983 280zx, When the car warms us it starts to idle rough, and eventually will shut down. When the engine cools back down again it will run like a top.

I did a little reading and read somewhere that this is commonly caused by the Cylinder Head Temp Sensor, does this sound right? I ordered a new one from Nissan and want to make sure that replacing this will take care of the problem before i go and pay for it.

Someone else said to check the mass air flow, but i find it hard to believe it would be cause by this due to the temp. issue.

Anyone else have this problem?

NismoPick

Welcome to ZDriver!

When it shuts down warm, will it start back up? Hard start? Easy start?

A motor needs 3 things to start:
-proper air
-proper fuel
-proper spark

If it won't start, check for spark and fuel (no fuel or flooded).

uranus

It starts again when warm, Its easy enough i have to give minimal gas.

Took the AFM apart to make sure that nothing was blocking and working properly, it has a clear airway.

I know it is getting plenty of fuel at least at the filter. I opened the out line on the filter and the gas was under pressure so it sprayed all over, a little upset about that. Now i am not sure on pressure or blockage after the filter. But i can rev as high as i would like while the engine is cold and it runs fine.

I have spark at each cylinder, Took rotor apart cleaned it, not too much wear on it.

After it shut down when it got hot i took 2 of the plugs out to see if i could smell gas on it, Plugs had hardly no gas on them or the smell.

Does the CHTS help control the air to fuel mixture?

NismoPick

Indeed. The CHTS, AFM, and O2 sensor are all related to a/f mix.

Have you tried unplugging the CHTS to see if that makes a difference? And you might want to check your local parts store prices before buying from Nissan. IIRC, Nissan's price is almost double parts store prices.

uranus

Well, i already replaced the replaced the o2 sensor.

Does the AFM work? Is air forced in it from driving?

Yeah i tried all the local stores for the chts, nobody can help me out. The 5 places I went to kept trying to sell me a coolant temp sensor.

IF I unplug the chts before starting the engine it sounds like the timing is off, it sputters, and i get a black smoke from exhaust. Same result if i unplug while running.

Also, there is a sensor light lit on my gauge cluster, Know what thats about?

NismoPick

Yeah, many parts stores still list it as coolant temp sensor because pre-79 FI Z's didn't have a CHTS, it was a coolant sensor in the thermostat housing... it's the exact same sensor: http://www.autozone.com/autozone/par...er=125559_0_0_

The sensor light on the dash is the 30K mile O2 sensor advisory. You unplug a wire on the right bottom of the dash (read up about it in the Haynes / FSM).

uranus

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uranus

Attached is a link of what is going on. May be helpful maybe not.

http://www.youtube.com/watch?v=h6BRWKO3jPg

sorry, i didn't realize i couldn't embed anything on that last post.

uranus

Okay, so i just put in a new CHTS, and same issue. When it gets up to operating temp it starts to idle rough and then eventually sputers out and stalls. I have replaced the o2, the chts. I dont want to have to look into a AFM, or the ECU but i think i an running out of options. Did notice that the water light came on on the dash. Does this have something to do with it? The engine runs perfect when it isnt hot. Any Ideas?

ls1angela

how long does it take , time wise , before problem starts ? noticed it idles hi before problem occurs . rec. you check your idle mixture screw and vac. leak around the intake .

uranus

The idle mixture screw on the AFM? I cant hear any vacuum leak anywhere. But i will check.

ls1angela

no . screw use to set idle . you can either use a smoke machine to check for vac. leak or carb spray .

skittle

Even propane will work for a leak. How is your thermostat, it the car is overheating that would make it shut off.

uranus

YEah i was thinking about the thermostat, My water lite is on in the dash. So i will check that.

uranus

So I changed out the thermostat. The water lite turned off on the dash. However, i am still having the same problem. When it gets hot it sputters and eventually stalled. At this time i have replaced the Thermostat, CHTS, and the o2 Sensor. It still feels like a fuel issue, running too lean when its hot. I'm kind of lost at this point. I don't know what steps to take next.

uranus

So my water warning lite is back on. What does this mean?

BlueKitsune

it says. Fill your coolant overflow.

as for your other issues. corroded connectors can get worse as they get hotter sometimes, I'd run back thought and make sure ALL your connects are clean (give them a 3-5 min bath in Tarnex to clean the inside of the connectors easily) after that I'd run and ohm/volt test to make sure everything is working fine and is connected properly. And if everything is fine after that its either you have a bad ECU, or your head is warped and lifting from the block when it gets hot. Are you loosing coolant or oil? Or is either of the two milky?

uranus

IM not loosing any coolant, or oil. They both look the way they are supposed to. Filling the overflow did make the water indicator go away. When you say connections you mean on the sensors, and ecu?

FricFrac

I've heard the S13 SR20 rads work.... and from eyeballing it it looks promising with the lower rad hose inset so it doesn't hit the cross member like the S30 rad does....

This might do the trick..... may as well get the fans too - cheap!

http://cgi.ebay.com/ebaymotors/Radia...Q5fAccessories

uranus

Okay, So i waited until it got to the point where it started sputtering. A friend of mine suggested checking fuel pressure after checking my filter. Checked the filter, it was good. While the car was idiling i had good pressure when the car started to sputter i had low pressure, makes sense. So i then just squeezed the fuel hose from the filter to the line and found that when i gave the engine artificial pressure by squeezing the hose it ran the way it was supposed to. So by just squeezing the hose off and on i could get the engine to fluctuate. It ran better when i had the hose squeezed until it of course ran out of gas then i would let go of the line to fill the hose again. Then it would start to sputter, i would then squeeze the hose and it would run fine until out of gas. Any ideas? Fuel pump, Pressure regulator, or something a little more complex, AFM, Ecu?

BlueKitsune

FPR is broken I bet they just randomly go bad sometimes. My old one was actually leaking fuel into the intake from the vac line

ls1angela

you need to squeeze the return line to see if fuel press. comes back up . i had the same problem with my 79 and 83 turbo . both had clogged filter at fuel pump inlet , a small cone shaped filter , you can remove and clean it . noticed you haved changed a lot of parts already . sometimes it is cheaper to take the car to a qualify repair shop for diag. , cost usually about one hour up front . i've work in this bussiness for over 15 years and see people try to fix car themselves by throwing parts at it . finally they give up and bring the cars to my shop , sometimes i found a broken ground wire that caused all kind of problems . what i'm saying is that it's cheaper to have a shop look at rather spend money and time try to do it yourself . good luck , let me know about your fuel press.

modrod

I have a 1983zx and I am experiencing the same problem. Tends it only happen when I am in stop and go traffiic and the car is idling. It eventually choke itself out like it is out of gas.
Uranus, did you ever find the solution to the problem. Any advice would be appreciated.
thanks

uranus

Took the car to a mechanic, Found out the fuel pump was not delivering enough pressure to the engine, So i replaced the fuel pump, now i have a bad relay somewhere. the fuel pump only turns on when you turn the key on. When you try to start the car it isn't getting any power. Any idea which relay is bad.

Looks like all my issues are fuel issues.

ls1angela

dont think you have a relay problem because you stated that it has power with key on . ecm controls fuel pump relay . check ignition switch , make sure it has power when in start position . does it have power to the rest of the systems like ignition ?