Hey, so this is my first time to this website and I think this place is awesome, I definately wish I had found this place earlier with past troubleshooting, but onto today's (well this past week haha) problem...

The car is a 1983 280ZX (non - turbo)
When the car is first started (cold) it seems to run fine - idles and revs up when you add gas like it should. But after it gets warmed up, about a minute or alittle more later, when you add gas it kind of bogs down instead of reving up like it did when it was first started. It also sounds like it misfires a bit when it is full throttle and it is struggling. When you let off the gas it goes back to idling just fine.

To try to fix this problem I have:
replaced the vacuum hoses (since they have never been replaced)
to the best of my knowledge, made sure the EGR control valve, the PCV valve, both work properly
Checked the timing - it's correct
Cleaned electrical connections (like the distributor and thermal switch, you know the top most one with the fuel injector type connection and other misc. electrical connections)
I've disconnected the water temperature switch that feeds the distributor and that didn't change anything

So... I'm kind of at a loss now, Any ideas or suggestions?

 

Welcome to ZDriver!

Have you tried replacing the fuel filter yet...?

Rod.

 

No I haven't replaced that yet, what I did in the very beginning was i unhooked the downstream hose and turned the car on to where it would prime the system and it was spraying out just fine so I guessed that it was fine but I'm gonna go do that right after this post just so it's done

man i totally forgot about adding that to the list - it seems like so long ago, I was sitting here thinking I knew I did something else but I couldn't remember it.

So lemme go try that

(and thanks for the greating! )

 

okay so i replaced it and at first it seemed to be better (since it was started at cold again) but it warmed up and the problem is still there... sorry, i was really excited at first though

any other thoughts?

 

replace the coil. its gonna be the coil. this happens when it gets warm and it just doesnt fire like its supposed to, thats what creates the missfire/bog condition. while your at it go and get an msd blaster 2 coil, its worth it and a direct replacment for your stocker. oh and welcome to zdriver.

 

might as well replace the plugs while your at it, never hurts.

 

Have you checked the AIR REGULATOR ? That's it's job... to help the idle transition from cold to hot. Check the wire connector & all hoses around it.

 

sounds like a worn out distributor cap and rotor? i know in my g.f. 1983 280zx non turbo.. auto tranny it was running good when it was cold and when it warmed up ran like crap... but thank god she has me ( i love to work and tinker with my 1982 280zx turbo ) also could be loose fuel injector connections after 25 years they do crack and do get coroded... and turn green..

 

I'd go with coil on this one. Heat creates resistance, so pretty much any ignition component can be affected by heat. Make sure you check your plugs as well. If they are bad then they can have a tough time firing the leaner mixture of a warmed up engine.

Don't overlook your o2 sensor though. It only sends a signal to the ECU once the engine has warmed up (hint, hint ).

EDIT: Oh, and welcome to ZDriver.

 

I have that problem as well but in reverse... Its a hellion to start up and run but as it gets going and warmed up for about 20-30 mins it has no problem it acts like its a carb but its injected.

 

skittle I'd say your's is almostly definitely the air regulator.

 

hmmm i guess that means i need to change that out then huh... lol well when i get back to the states where would u should i get one at and what pricing are they so i can order one and have it delivered to my house when i get back from iraq?

 

I know blackdragonauto.com carries them. As does zcarparts.com. I think they sell them for around a $100.00.

 

Hey thanks, I think I'll check out the coil since that seems to be a very good idea and it will be a whole lot easier than trying to change out the thermal vacuum value (I think that's it's name) which was my next guess. I also have a friend who thought it could be the O2 sensor also but I was unable to snag one at the junkyard yesterday

The majority of the electrical connections I have gone through and cleaned off with sandpaper so I hoping that isn't a problem.

I'll let you know what happens with the coil!

Thanks you guys, it's amazing how much feed back I've gotten already!
THANKS!

 

Dont get an o2 from a junkyard. Chance are it'll be bad. You can get them for like $35.00 new.

 

oh okay that's not too much, the Z's at the junkyard I keep going to tend to be police auctioned ones that were running before they were taken there for whatever reason and prices are really cheap so I was hoping they'd have one - but they didn't and i'm not exactly sure but I think they warrenty what you grab :? atleast they tell you when you buy a trans from them that there is no warrenty, who knows

anyways it would have been really cheap (i got t-tops for $15 and also the whole thermostate with all the sensors to swap out with my sensors to find the problem for $3) but $35 isn't bad either, even if it isn't what's wrong, i can save it till it is what is wrong haha

 

yeah it's good insurance. I replace the o2 on any used car I buy that doesn't have documentation that it was recently replaced. Replacing that little sensor can save you some headaches in the future

 

p.s. this junkyard is like the wal*mart of junkyards, i went there 3 months ago and they had 3 280zx's, when I went there yesterday, there were 2 completely different 280zx's

...rediculous... oh well... i can't wait till tomorrow to get this coil thing tested and grab a new O2 sensor! I miss the Z!

oh yeah, i've heard that the O2 sensor on new cars will cause massive problems, especially with the check engine light coming on - does that come on with the Z if the O2 doesn't work?

 

Nope, no check engine light in the Z. There is an o2 replacement light but it's only good for the first time the sensor needed to be changed. I think it was something like 60,000 miles. Then the light just gets disconnected never to be used again.

 

ahh yeah, just a few miles over 60,000 - thanks for that info though i'm gonna have to stop by an auto place tomorrow, it's a shame they don't have 24 hour ones hahahah

 

Alright, so I replaced the ignition coil but sadly my problem is still here... but I do have some more info
this time with the new coil after a few minutes of it running when i put it at about half throttle it would bog down a bit then slowly rev up, better but not normal. With it at full throttle it would bog down and not rev up at all and miss-fire though.

I'm going to replace the O2 sensor when I get back home (since I had to go to work - and am still here) but I don't have much faith in it making that much of a difference but i'll let you know the outcome of that

 

It really just sounds like a sensor (fuel) problem. A coil won't fix that.

Have you ever adjusted your AFM? I would suggest investing in an air/fuel gauge so you can see what's going on w/ the mixture. If it's running too rich or lean, you can adjust the AFM to make it run better.

 

I didn't really adjust the AFM but I replaced it with another one and it still has the problem going on. I don't know if I'd have to adjust the mixture manually because it was running just fine before this all happened and it seems kinda weird that it would just happen but hey anything could happen right? I also checked the spark plugs and man were they dirty, I haven't replaced them since 2 summers ago so I replaced them today. Also the resistance in the spark plug wires is just fine and doesn't change much as the temperature rises.
As for the distributor and such things I re-cleaned all the connections and it should be just fine.
But I still haven't replaced the O2 sensor because I always forget to try to take that out before it gets hot and then I have to wait for it to cool down and etc so I hopefully will give that a try soon.

this one is definately tough for me so i appreciate all of the ideas so far

 

You will be amazed at the difference an O2 sensor can have on the driveability of your car...

 

So I finally replaced the O2 sensor on the beast and still no bueno...