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Discussion Starter · #1 ·
Hey there, first time posting but been reading for years now. I'll try to make this a clean and concise as possible.

I have a 1981 280zx. About 160,000 miles and is usually my daily unless my Geo breaks down.
I prefer to drive aggressively and recently developed a problem while shifting. If I shift anywhere between 5 and 6.5k rpm, and come of the clutch quickly, the car lurches and I get heavy sputtering for about a half a second. This happens in all gears. The loss of power during that half second is significant and the engine has to struggle to catch up.
Shifting around 7k significantly reduces this and sometimes stops it especially if cooler out.
So far, based on reading similar issues here and making shots in the dark, I have done the following.
Replaced the batter and starter and ignition switch ( not for this issue)
Replaced the ignition coil.
Installed an inline fuel Guage. ( Readings are perfectly inline with fsm.)
Replaced ECU
Replaced afm
Replaced coolant temp for gage cluster because it didn't work.
Replaced thermostat and housing when it broke during thermostat replacement.
Put in brand new fuel injectors along with a new fuel rail for good measure.
I did compression test and was 185-190 psi on all cylinders with one at 160. I know that's not wonderful but it's better than I expected and put me back to the dwg board.
Did a noid test and all my injectors. They're all getting power.
New spark plugs all around.
Adjusted timing to 800 rpm idle and 10° and it runs a bit better now and starts up easier but didnt fix the stuttering issue btwn gears.
Aso did a vacuum test and came out to near perfect vacuum.
Fuel pump was replaced last year and whines like they all seem to.

I'm half expecting fauci to announce that cars can get covid now too and I can just euthanize the darn thing.

Please send help and suggestions.
 

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Yeah, this is a weird issue... one that I also have never seen before.

If were to suggest anything, I would say...
First, stop coming off the clutch quickly and stop driving the car aggressively. Refer to the owner's manual of the proper time when you should be shifting gears.
Second, stop throwing parts at it. It seems that you've done everything except a basic tune-up. How's your air filter, fuel filter, cap and rotor, plug wires... are the plugs NGK? Are they gapped correctly? What is your fuel pressure at the manifold? I'm just stating the simple stuff to look at first.

You mentioned this problem started developing recently... did it start after you replaced or changed out any components? or did it just come out of the blue?

Bon
 

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Discussion Starter · #4 ·
Yeah, this is a weird issue... one that I also have never seen before.

If were to suggest anything, I would say...
First, stop coming off the clutch quickly and stop driving the car aggressively. Refer to the owner's manual of the proper time when you should be shifting gears.
Second, stop throwing parts at it. It seems that you've done everything except a basic tune-up. How's your air filter, fuel filter, cap and rotor, plug wires... are the plugs NGK?
I'm just stating the simple stuff to look at first. What is your fuel pressure at the manifold?

You mentioned this problem started developing recently... did it start after you replaced or changed out any components? or did it just start out of the blue?

Bon
Some of the parts I've thrown at it are off of a buddies z that he has torn down ( just for troubleshooting purposes ( such as the ECU,TPS, maf, cold start valve))

Plug wires are brand new ngk, fuel filter is new, air filter is about 6 months, cap looks new and rotor seems to be in good condition as well.

It seemed to start out of the blue in the heat of south Carolina summer and slowly got worse over the course of a month and steadied out where it is now.

I haven't been driving as aggressive with the problem recently but there is the desire to do a pull with all the neat cars in the area and it's painfully to fall significantly behind because of this issue. If it wasn't happening I would only lose by quite a bit instead of by a looot.
 

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Hmmmm.... well, looks like the tune up stuff is good to go. Can I ask, was your ECU, AFM, and TPS failing? No reason to replace those unless they have failed
(ECU's and AFM's typically don't)
I'm wondering if you're getting some kind of weird heat soak issue? Probably unlikely.

Don't try to boost your driving pride or ego at the expense of hurting your car by trying to impress the idiots in neat cars, new cars, or whatever.
You may not be able to hang with them, but remember:

You're driving around in a slow 40 year old, solid-built, unique car, with some style and class...
They're driving around in expensive, modern, neat and fast pieces of junk made of plastic that will most likely fall apart after a few years...
No need to go down to their level just because you have a beater car. New is poo, and old is gold my friend.

Now, back to the issue at hand... does it still do it if you drive it normally, soft and easy, at slow speeds?

Bon
 

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Discussion Starter · #6 ·
Hmmmm.... well, looks like the tune up stuff is good to go. Can I ask, was your ECU, AFM, and TPS failing? No reason to replace those unless they have failed (ECU's and AFM's typically don't)
I'm wondering if you're getting some kind of weird heat soak issue? Probably unlikely.

Don't try to boost your driving pride or ego at the expense of hurting your car by trying to impress the idiots in neat cars, or new cars whatever. You may not be able to hang with them, but remember:
You're driving around in a slow 40 year old, solid-built, unique car, with some class and style...
They're driving around in expensive, modern, neat and fast pieces of junk made of plastic that will most likely fall apart after a few years...
No need to go down to their level just because you have a beater car. New is poo, and old is gold my friend.

Now, back to the issue at hand... does it still do it if you drive it normally, soft and easy, at slow speeds?

Bon
As far as I can tell, nothing had obviously failed. Never know other symptoms or signs that I can tell might be causing the problem.
My biggest concern is that this is an issue that may transcribe to other issues in the future so I'm trying to hunt down the gremlin before midnight If you know what I mean.

Driving it soft and easy, the problem doesn't seem to present is self hardly at all. During down shifts I tend to get a bit of sputtering. Fuel efficiency is probably sitting somewhere around 11 mpg but has been that way for years. If I remember correctly, which I probably don't because it was about 8 years ago that I bought the car, it did get better gas mileage then.
 

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Discussion Starter · #8 ·
11 MPG is awfully low. Even if you were doing all in-town driving and launching at every light that would be low.
After all of that troubleshooting then I have done, I honestly don't have the slightest idea where the rest of my miles to the gallon could be going.
Fuel pressure at the rail maintains at 30 psi pretty much constantly. I didn't start it up for about 2 weeks and when I came back it was still there so I'm apparently confident that I have the tightest, most leak free fuel system in the datsun universe haha
 

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You said you replaced the AFM, ECU,TPS, and CSV from a buddy's parts car.... Why? And what year and model was this parts car?

Bon
 

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Discussion Starter · #10 ·
You said you replaced the AFM, ECU,TPS, and CSV from a buddy's parts car.... Why? And what year and model was this parts car?

Bon
This has been my first project car. I've lurked on these forums for a long time and almost all of my know-how comes from here, the FSM, and YouTube videos.
I didn't really know where else to turn when the problem persisted after the simple troubleshooting concluded. So, with another 81 280zx parts car, I figured I could very easily interchange parts that I knew to work for once that could have been faulty. When the problem persisted, I put back in the originals. I was only using parts from his car briefly to see if they solved the problem.
At this point, I didn't know what could have been the possible issue so I was trying out anything that I possibly could.
A better mechanic probably has a better solution, and I'm hoping that one day I may get there.
 

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hmmmm, ok. got it.

tell me about the fuel pump... you replaced it correct? with a stock unit or some other?
perhaps there is an issue back there with it? maybe not putting out what is required or fuel cutting at different points. do you still have the original pump?

as far as mechanics go... nowadays can be tough to find one who's worth their salt when it comes to your old Z car. you could trying going to the nissan dealership and if you're lucky there might still be a few old crusty Z guys that have experience on Zs. but in my experience they are now so few and far between. And some mechanics now either don't know how to work on your Z or flat out won't work on it.

you'll get there eventually. you've got to nail this problem though... you know and it might just be something really simple. I think its fuel related, but I'm just not sure.
Do you have any Z car clubs close to your area?

Bon
 

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May not help, but had a similar problem in a Chevy Vega once. Turned out to be the igniter and pickup coil in the hei.
Check your distributor and make sure that you aren’t getting any interference in the pickup coil.
 

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Discussion Starter · #13 ·
hmmmm, ok. got it.

tell me about the fuel pump... you replaced it correct? with a stock unit or some other?
perhaps there is an issue back there with it? maybe not putting out what is required or fuel cutting at different points. do you still have the original pump?

as far as mechanics go... nowadays can be tough to find one who's worth their salt when it comes to your old Z car. you could trying going to the nissan dealership and if you're lucky there might still be a few old crusty Z guys that have experience on Zs. but in my experience they are now so few and far between. And some mechanics now either don't know how to work on your Z or flat out won't work on it.

you'll get there eventually. you've got to nail this problem though... you know and it might just be something really simple. I think its fuel related, but I'm just not sure.
Do you have any Z car clubs close to your area?

Bon
I replaced the fuel pump. Couldn't afford the stock $800 one so I replaced it with one that I think cost about a hundred bucks from O'Reilly's. Unfortunately that's about all of the information that I remember from replacing it. At risk of sounding like a s***** mechanic, old me probably tossed the old fuel pump in the garbage and called it a day.

I consider taking it to a Nissan dealership but didn't think that they would know much of anything about it. There is a z shop up in North Carolina. I figured that if the experts on here couldn't help me make headway, I might make the trip.
 

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Where are you exactly in NC?

I don't know of any specif Z specialty shop around the state, but there is a place in my town (Fayetteville) called 'Cruizin' Auto. They work on a bunch of Zcars and some of the skylines and silvas.
I took my 280zx in there last time to help troubleshoot a fuel issue that I was having. They started up a little Z car club too for Fayetteville. And as far as I know, Covid hasn't shut them down.
Maybe give them a shout.

Bon
 

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Turned out to be the igniter and pickup coil in the hei.
Check your distributor and make sure that you aren’t getting any interference in the pickup coil.
UncleWiggly may be on to something there.
I have seen where those distributors have plastic parts that break in the vacuum advance mechanism. It holds the ball bearings in place. Balls will come out and roll around. Also, the wires on the pickup coil flex every time you accelerate. They may break after 40 years. Pickup coils are cheap at RockAuto. Be very careful with the magnet under the pickup coil. They are fragile and there are none in captivity.
 

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Discussion Starter · #16 ·
Where are you exactly in NC?

I don't know of any specif Z specialty shop around the state, but there is a place in my town (Fayetteville) called 'Cruizin' Auto. They work on a bunch of Zcars and some of the skylines and silvas.
I took my 280zx in there last time to help troubleshoot a fuel issue that I was having. They started up a little Z car club too for Fayetteville. And as far as I know, Covid hasn't shut them down.
Maybe give them a shout.

Bon
I'm in Charleston south Carolina. I don't know of anyone terribly close to me. I thought there was a z shop in north carolina but I'll have to look into it.
 

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Unless your engine has been cammed up your over revving your engine which is abusive. The stock engines should not be taken past 5500. After that they fall flat and can start causing problems. The valves start to float at about 6800 rpm if you have stock valve springs and if the engine hasn't been balanced during a rebuild then you're going to ruin your crank and crank pulley. You should put your idle speed at 900. Driving aggressively is ok as long as you're not over driving the engine. Z man of Washington
 
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Discussion Starter · #19 ·
Unless your engine has been cammed up your over revving your engine which is abusive. The stock engines should not be taken past 5500. After that they fall flat and can start causing problems. The valves start to float at about 6800 rpm if you have stock valve springs and if the engine hasn't been balanced during a rebuild then you're going to ruin your crank and crank pulley. You should put your idle speed at 900. Driving aggressively is ok as long as you're not over driving the engine. Z man of Washington
I appreciate the advice and will most definitely change my driving style until I can make the necessary upgrades.
 

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Hey there, first time posting but been reading for years now. I'll try to make this a clean and concise as possible.

I have a 1981 280zx. About 160,000 miles and is usually my daily unless my Geo breaks down.
I prefer to drive aggressively and recently developed a problem while shifting. If I shift anywhere between 5 and 6.5k rpm, and come of the clutch quickly, the car lurches and I get heavy sputtering for about a half a second. This happens in all gears. The loss of power during that half second is significant and the engine has to struggle to catch up.
Shifting around 7k significantly reduces this and sometimes stops it especially if cooler out.
So far, based on reading similar issues here and making shots in the dark, I have done the following.
Replaced the batter and starter and ignition switch ( not for this issue)
Replaced the ignition coil.
Installed an inline fuel Guage. ( Readings are perfectly inline with fsm.)
Replaced ECU
Replaced afm
Replaced coolant temp for gage cluster because it didn't work.
Replaced thermostat and housing when it broke during thermostat replacement.
Put in brand new fuel injectors along with a new fuel rail for good measure.
I did compression test and was 185-190 psi on all cylinders with one at 160. I know that's not wonderful but it's better than I expected and put me back to the dwg board.
Did a noid test and all my injectors. They're all getting power.
New spark plugs all around.
Adjusted timing to 800 rpm idle and 10° and it runs a bit better now and starts up easier but didnt fix the stuttering issue btwn gears.
Aso did a vacuum test and came out to near perfect vacuum.
Fuel pump was replaced last year and whines like they all seem to.

I'm half expecting fauci to announce that cars can get covid now too and I can just euthanize the darn thing.

Please send help and suggestions.
I had a similar problem with my 78 280z
how I solved mine.
I went through every single connection on top of the engine cleaned all I could find and replaced a couple. To my amazement that solved my problems runs good now
Good luck
 
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