Hi

ok so the 1983 280zx...seems to be losing power. Almost like running on 5 cylinders..but I checked and cleaned the plugs. Also it may be electrical...it seems that when I give it the gas the lights on the dash for the brakes...door open..go on and go off when it idles down Also the gas low light goes on and I have a half tank...The volts light goes on as well. new battery charges at 14.5....

Tried dry gas and fuel injection cleaner...maybe its volts or something I dont know...I will have to have someone look at it any suggestions?
thanks

Barry in Fairfield

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1983 280ZX 5 speed T-Top Gun metal gray

non turbo? Idle goes too low and dash lights come on....right? Sounds like normal ZX behavior. Do make sure battery connections are good first....no corrosion, and tight. Alternator putting out more than 13.6 volts....basically 14v. 12.v = no charge. If all checks out there.... turn up the idle.......left side engine center of manifold close to fender....big screw. (inset)

Paul thanks,
it is not that idle goes lower and lights come on..it is the opposite, give it gas and lights go on......

Battery is 3 months old clean terminals...

volts reading at 14.5 is that no good?

needs more thought on my part and dare I say it a better mecahnic than I


all the best

Barry

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1983 280ZX 5 speed T-Top Gun metal gray

["...it seems that when I give it the gas the lights on the dash..go on and go off when it idles down..."]
Hi Barry ~ are we completely sure those lights aren't on all the time? I mean, is there a chance that they are simply too dim at an idle to be seen in the daylight? Have you let it idle at night with the headlamps and parking lamps off, to see if you can see faint dash warning lights?

It seems it might be easier to solve if that's what was happening; then we would know that by running the rpm up, your alternator is supplying enough juice to light them all up, but the battery wasn't able to.

And is it always the same warning lights, or do they sort of alternate?

Just a thought.

Frank

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1970 240Z

Thanks Frank I will try it tonight but I suspect they are really going on when I increase the rpms....I am wondering about voltage regulators? sometimes the oil pressure gauge is funky...will try tonight after dark thanks

Barry

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1983 280ZX 5 speed T-Top Gun metal gray

sounds to me like a bad voltage regulator, and on your year car the regulator is vuilt into the alternator. Take the car to Autozone, they will plug it into their big ole diagnostic machine and test the alternator, regulator, battery, etc for free.

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71 on a rotisserie, two more in pieces in my shed...and a 69 1600 waiting for me to get to it

ok thanks I will try that

Barry

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1983 280ZX 5 speed T-Top Gun metal gray

If it's a non turbo, what does your gauge say when it is running.......they are accurate on the ZX. If it's a Turbo, and you are not charging, the clock will fade on one side.

Hi thanks for your response .... it is a non turbo The volt gauge says 14.5 temp seems to be normal. oil pressure seems a little erratic at times.....but mostly the same

a backyard mechanic friend says it is almost like the symptoms show that there was a problem with a cat converter except this car has no cat converter....all pollution control stuff seems to have been removed by prior owner...It has nice headers coming off the manifolds to a nice straight pipe...

He said maybe it is a problem with the on board computer and he knows nothing about these z cars.. He did eliminate normal stuff like alternator, plugs, wires distributor cap coil all tested fine....

I might have to take it to the Nissan dealership in Fairfield if I cannot find a knowledgeable person to look at it....any suggestions on mechanics?

thanks again

Barry

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1983 280ZX 5 speed T-Top Gun metal gray

Weird.
Very hard to diagnose a stray electrical voltage by long-distance, which is what this sounds like. I can't picture how exhaust or even injectors could factor into this equation. I would have suspected a bad voltage regulator, but you say your voltmeter shows full 14.5v charge, which leaves me pretty baffled. Maybe that 14.5v is leaving the alternator but not reaching the battery...?..that could be tested across the battery top with a Multi Meter but not over the website. Trying to picture why the voltage would go someplace else (someplace wrong) when the rpms increase but not at idle....
Sounds like a possible short somewhere. Not enough voltage to push current across the gap at 12v, but as soon as you exceed 12v (rev the engine) the increased voltage jumps the gap? I dunno. Also weird that you're getting odd warning lamps like brake light and such. Makes me suspect an under-dash short, or a computer problem like your friend suggested.
You could run your hands over your entire wiring loom inch by inch, searching for any place where the insulation has worn-thru and a spark might jump to ground. You could also turn all the lights out in the garage and watch your engine bay in total darkness for sparks while someone runs your rpm up (DANGER ~ CO asphyxiation threat! Don't do this for long!).

Beyond my capability over the website, that's for sure! Sorry.
Anybody else?

Frank T

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1970 240Z

Frank

Thanks for your response. I like hearing from you guys even when it is hard to explain what my problem is.....

I will try the dark garage ....


Also you make me remember something I did last march.....


So when the car was away for the winter I did not trickle it and I did not run it....so the battery went bad... Bought a new one and everything was fine except I noticed this little red light next to the ash tray.. Some alarm type light I guess....but it stayed on all the time and it made me think that is why I killed the battery....so.......I cut the wire and the light went out.......I forgot about it until your response here today.......


this might be an issue although the car ran great in April may and June till it was down for 6 weeks with my new tire search.......


I wonder if tonight I should just reconnect that wire and see what happens..... doesn't sound like it is the problem...but that's what I get for doing my own backyard home mechanic fix without really knowing enough........


thanks again

Barry

p.s. wife is starting to suggest I sell the car that I cannot drive when it is broken and cannot drive in the winter etc...... I would only consider this if I can replace it with a used 350z or 370z

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1983 280ZX 5 speed T-Top Gun metal gray

Red light might be a rear hatch glass defroster "on" warning. Others might know.

Tell your wife the best time to sell a Z is springtime (just like motorcycles).

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1970 240Z

I don't think that's the issue, but of course hard to really say if I ain't there looking at it. You also said like running on 5 cylinders.....keep in mind could be 2 completely different issues, or could be linked. I also see the lights go on when you rev it up, sorry I misinterpreted that, usually they can go on if idle is to low. Check the wires on back of the Alternator, and check all harness connections under the hood to all the sensors and injectors. You just might have to pull them and check for corrosion, and start cleaning with very tiny file. Shinier the better. Also, check computer harness connector. Right by your left foot. A car this old, even if kept clean and impeccable all these years, It is still not resistant to corrosion. Especially where it is humid, then add salt. All you need for this job is a dental pick, very tiny file, Philips screw driver and some beer and patients.