83 280ZXT running issue

A forum for owners of S30 and S130 Datsun Z's... 240Z, 260Z, 280Z and 280ZX!
FrenchPople
Posts: 81
Joined: Thu Jan 22, 2015 9:34 pm
Car: 1983 Datsun 280ZXT 2+2
2016 Nissan Frontier Crew Cab Desert Runner 2WD

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Hello im having some trouble with my 280zx. when i first start it up in the morning i have to let it warm up for about 5-10 minutes be for i can drive i(might be normal but not sure), after its has warmed up its ok for the most part. while its idling it sound smooth but yet it sounds like you can hear a slight miss every now and then and does it while im driving down the road as well with the slight miss when cruising at 60mph. if its warmed up and i decide to turn it off then start it up about 5 minutes later or so she barely want to idle(like around 500) and almost die. also when i do to turn the lights on at an idle the do dim and go bright when i bring the rpms up. and if anyone asks no the battery light doesnt come on while its running. has anyone ran into this kind of problem befor? if so please help in any way you can thanks.

one one other note to add i did check the voltage at idle without and accessories running and it was at 13.8


NismoPick
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81 Datsun 280ZXT
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Welcome!

The rough cold idle is likely a stuck air regulator. Pinch off the hose between the throttle body and air regulator and see if the idle drops when cold. If it doesn't, you know the air regulator is stuck closed.

Also, when was the last tune up? A tune up and complete check over will do wonders for a tired engine. And check all the EFI connectors for corrosion. I actually sell a quick connect EFI kit to replace all the brittle and corroded stock connectors:
https://www.facebook.com/photo.php?fbid ... =1&theater

FrenchPople
Posts: 81
Joined: Thu Jan 22, 2015 9:34 pm
Car: 1983 Datsun 280ZXT 2+2
2016 Nissan Frontier Crew Cab Desert Runner 2WD

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The car itself has about 95k original miles on it. I'm the 5th owner and I think he last tune up was about 10 years ago but only 20 miles were put on it befor I got the carin November. Befor he last owner was in the process of restoring the car and rebuilt the distributer because the cam/crank angle sensor was bad. And when is cold in the morning the idle starts at about 1500 and gradually drops down over time. Since I have had the car I have put about 400-500 miles on her.

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evildky
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How are the plugs and wires? Perhaps your "miss" is an actual misfire. Old plugs and wires and cheap and easy to swap, another common cause of misfires in the L28's is the injector clips, especially on the turbo, the injector clips and pigtails get heated and dried out so much they become brittle and can break and loose connectivity, give each of them a wiggle and see if the engine sounds any different, replacement pigtails are cheap and just a matter of soldering or crimping them on, the difficult part is sometimes you have to cut back into the harness a bit to find good wire.

A real common issue for these cars is the CHTS. basically if it or it's connection goes (same pigtail as the injectors) the ecu faults to cold which causes a rich condition. This rich condition is what you want for a cold stat, but once warm can cause the engine to flood, the )2 works has the same effect but to a lesser degree. You can try unplugging each fo them one at a time for a warm restart and see if it changes, if the unplugged sensors have no effect on a warm restart they aren't working.

FrenchPople
Posts: 81
Joined: Thu Jan 22, 2015 9:34 pm
Car: 1983 Datsun 280ZXT 2+2
2016 Nissan Frontier Crew Cab Desert Runner 2WD

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When I first went to the car I had to take Ike with the injectors because she didn't want to run well at all first thing when I got to her. So I have cleaned the injectors and had to replace at least 1 of the connectors bust most were ok after the cleaning she ran a whole lot better. Also I went ahead and changed the plugs as a just in case and will check them again today same with the wires. I will also give the chts to see if it is having problems or not. Thanks for the help I will Che k some things out if anyone els has any Ida's please let me know. Thanks

Also yes I did make sure I put the NGK plugs in there

FrenchPople
Posts: 81
Joined: Thu Jan 22, 2015 9:34 pm
Car: 1983 Datsun 280ZXT 2+2
2016 Nissan Frontier Crew Cab Desert Runner 2WD

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Ok so I did some checking on the car yesterday and here is what I came up with. Th Chts checked out ok, no connectors were corroded, no wires were chewed up or missing. I went ahead and changed the spark plug wires and it helped considerably, I took my dads fluke meter and checked the batt voltage while it was running. At idle no loads running at 13.98 and 14.2 at around 2500 rpm. With all the lights on it idled at 13.6 and when I brought it up to 2500 Roma it was lucky to get to 13.7. Also I wa looking the injectors and I have 3 different colors. 4 that are blue and a white and a black. If there is a problem with that tha anyone here may believe please let me know it would reay be appreciated. Thanks

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sakurachuck
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Joined: Fri Feb 24, 2012 5:19 pm
Car: 1974 Datsun 260Z
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FrenchPople wrote: Also I wa looking the injectors and I have 3 different colors. 4 that are blue and a white and a black. If there is a problem with that tha anyone here may believe please let me know it would reay be appreciated. Thanks
Well, the color of the stock L28ET injectors was Brown... The color won't necessarily tell you anything though if you're not sure where the injectors actually came from. You'd need to check the flow rate (have someone check the flow rate) to see if they are matched and have the proper flow for the L28ET.

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evildky
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Mix and match injectors are a red flag. Who knows what flow rate those are, even if they are equal to one another if they aren't the correct flow rate you'll be rich or lean depending on the flow rate of the injectors. The ecu is tuned for the stock injector (265 cc IIRC) anything larger causes the already rich tune to run richer, anything smaller and you risk leaning out. I'd definitely start by locating a set of stock injectors.

FrenchPople
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Joined: Thu Jan 22, 2015 9:34 pm
Car: 1983 Datsun 280ZXT 2+2
2016 Nissan Frontier Crew Cab Desert Runner 2WD

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alright i had the unfortunate feeling about the injectors and the sad part it all of them a remans that a nissan dealer in the phoenix area put in. went ahead and ordered the injectors and will get those done asap same with the cap and rotor. the lovely rotted exhaust pipe and muffler will be takin care of tomorrow

FrenchPople
Posts: 81
Joined: Thu Jan 22, 2015 9:34 pm
Car: 1983 Datsun 280ZXT 2+2
2016 Nissan Frontier Crew Cab Desert Runner 2WD

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ok so i got the injectors taken care of finally and man what a difference. at start up its great and i now have better power throughout the whole rpm range. but when it is warmed up i kinda notice it still slightly miss and the oil pressure is about 5-10 psi and to my understanding that is a big problem at idle. i did look around to try and find the leak and it looks like if it is at the head gasket between cylinder 3 and 4. has anyone seen a similar issue like this before and know a quick simple fix or am i most likely going to have to change the head gasket?

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djwarner
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Car: 1971 240Z Series I
2006 350Z
Location: Central Florida

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Low oil pressure after fully warming the engine is not unusual with our engines. The lubrication system is design to have a high flow rate rather than a high pressures. As the engine warms, the oil gets thinner and easier to push through the system, resulting in lower pressure. Also your gauges and sensors are 30 years old and never were calibrated. In fact the oil sender is designed to go open at pressures below 7 psi. Many owners are surprised after a highway speed run to see the oil pressure go to zero. If you are concerned, you can add a mechanical gauge.

I assume you are seeing an oil leak at the head between cylinders 3 and 4, above the oil filter. There is an oil passage between the block and head at that location. You may have a leak at the head gasket or a leak at the valve cover gasket. Oil consumption is the best indicator of the severity of the leak and other engine health issues. I had a similar leak at the head gasket caused by the design of the gasket. A NISMO gasket corrected the problem. However I would not tear into an engine just for a slow leak.

Get some time on your engine to measure actual oil consumption.

FrenchPople
Posts: 81
Joined: Thu Jan 22, 2015 9:34 pm
Car: 1983 Datsun 280ZXT 2+2
2016 Nissan Frontier Crew Cab Desert Runner 2WD

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I did replace the oil pressure sender already and I have double checked for the valve cover that itself is fine and its a very slow leak but the passenger side of the block is wet after a good drive and the location you just described is what I found. I'll take some time to see what it does

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evildky
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IT would also be a good idea to run a compression check, make sure the cylinders are all doing what they are supposed to, if the compression is good and you have a head gasket oil leak you might want to have the head gone through when you pull it, a cracked valve seat often doesn't show anything in a compression test but causes a mild stumble at idle that clears up with some throttle.

FrenchPople
Posts: 81
Joined: Thu Jan 22, 2015 9:34 pm
Car: 1983 Datsun 280ZXT 2+2
2016 Nissan Frontier Crew Cab Desert Runner 2WD

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Ok so I will also check the compression once I have some time. And I am a little curious. Will the nismo head gasket be arriving for the car since it is turbo? Yes it is stock but I'd rather be safe then sorry.

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djwarner
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2006 350Z
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Nissan Motorsports has several different head gaskets. Unfortunately, you cannot buy directly from them. You will have to work through a Nissan Dealer.

Again, they are not inexpensive so I would not be in a hurry to replace it. Compression check first. If compression is good, verify oil consumption first.

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evildky
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Nissan Motorsport used to deal direct with the public, geared towards racers. nismo was the street turning division geared to the streets and sold through dealers, unfortunately they merged and all but destroyed the nissan motorsports division.

Back on subject they thinnest will raise your compression a bit but still safe unless you plan to crank up the boost, in which case you can still run a thin head gasket but you'll want to add an intercooler.

FrenchPople
Posts: 81
Joined: Thu Jan 22, 2015 9:34 pm
Car: 1983 Datsun 280ZXT 2+2
2016 Nissan Frontier Crew Cab Desert Runner 2WD

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I plan on keeping her stock so from the sounds of it if I have to I'll probably get that one in particular but like said ill do some checking first. Also I do work at a Nissan dealer but unfortunately the parts guys are usually busy. Would any of you perhaps remember the Nissan part number that way it makes work a bit easy? As for the intercooler deal I'd like to find a bolt in setup that I won't have to do any modification if possible.

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djwarner
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2006 350Z
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Our engine models were not turboed. Try

http://parts.nissanusa.com/

Also, the first place to look for a miss at idle is a vacuum leak.

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evildky
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There is no "bolt on" intercooler setup that I'm aware of, greedy made a bolt in once upon a time. Most people just buy the intercooler that fits then start piping. Most do a cross flow intercooler requiring an electric fan to accommodate a crossover tube between the engine and radiator, I opted for a vertical flow which is actually more efficient and having the inlet and outlet on the same side makes for less piping and no need to mess with the fan.

On the miss, plugs and wires would be a no brainer to check as well.

FrenchPople
Posts: 81
Joined: Thu Jan 22, 2015 9:34 pm
Car: 1983 Datsun 280ZXT 2+2
2016 Nissan Frontier Crew Cab Desert Runner 2WD

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Plugs wires cap and rotor I have already changed because its been forever so I know those are fine and when cold she is great its just after warmed up now once I do a compression check ill see where to go from there. But like said if any of you have the Nissan part number for the Miami head gasket that would be great

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djwarner
Posts: 407
Joined: Sat Jan 23, 2010 6:07 pm
Car: 1971 240Z Series I
2006 350Z
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The guys at Nissan Motor Sports are quite helpful if you give them a call. They will find you a part number.


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