Hey you guys I was working on my car 280 zx 1979, and I notice when I punch it she dumps a lot of fuel in and she smokes, then clears up in a secound with the throttle still down. I figured this was normal, cause she dosn't bog, she dosn't hesitate, she say ror, and go's. I figured if ther is any problem, it could be that I might need to move my distributer a little bit because I thought maybe it could be spark time. like I stated thogh, she is running great. what do you guys think?

 

What color is the smoke & where is the smoke coming from???

 

its gas I do know that much, frome the exaust pipe. no leaks, just not burning it full enough for a minute

 

man I could cut a donut like that car in the picture

 

Well... at full throttle, it SHOULD dump a lot of fuel in. Try hooking up a timing light to check your timing, and for $40 you can get an air/fuel ratio gauge & check how rich / lean it's running.

 

Stupid me I forgot to mention I am runing just a header no cat no muffler, so I think this is normal since is only a quick secound. I mean she is snapy. no cat to burn that partialy burned fuel that flys out. do you think this is a reasonable diagnosis?

 

natrually asperated by the way

 

If I were actually driving down the road you wouldn't see the smoke, but if you were behind me you might smell it.

 

did your car have an oxygen sensor in the factory exhaust manifold? If so, do the headers have the oxygen sensor installed in them?

 

First answer Bleaches question cause that could be it.
If you DO have the O2 sensor installed then check your TPS position. It could be off which is giving the ECU the wrong signal. It could be that the TPS is saying the throttle is WOT before it actually is so that fuel gets dumped a split second before there is actually enough air to burn it with. WOT throws the ECU into closed loop which means full enrichment based on air temp and mass and dosn't give a damn about A/F ratio.

 

No this car isn't a cali car no o2 sensor, but I did replace the tps a wile back, not sure about the position aspect about it, I will check and see.

 

Maybe I should have stated clear, this car wasn't manufactured to take input from an o2. Its not a california model. so there is not suposed to be a o2 sensor.

um it really isn't a problem, I was just wondering more or less if any of you guys were runing straight pipes no cat or muffler, did the same thing?

 

An O2 sensor only puts out 1 volt. Which is the rich side. Most readings are going to be in mV. An ideal performance mixture is going to run up in the 800mV range. Dust, check the postition of the TPS. If you need any help on how to do that let us know. Myself, or I'm sure someone else on here can do so. If you're only getting smoke when you mash the throttle then the ECU wouldn't even take an O2 reading anyways (if it had one to begin with) At WOT the ECU only cares about air temp and throttle position to determine the mixture (on this car, newer cars are a little more advanced). The O2 only comes into play at idle and part throttle. And even then only when the car has warmed up. But smoke isn't neccessarily a bad thing. As I mentioned above, a richer than stock mixture is ideal for performance. 14.7 is only ideal for complete combustion and as a result, emissions. So if it's a light grey(can almost look white) color then I wouldn't sweat it. If it's white or dark gray/black then you could have yourself a problem.

 

Disregaurd that post...i was answering 3 different threads in the wrong forum too, i need to just keep one window open at a time from here on out. Sorry

 

well the smoke is light grey, so yea I guess you are right. no big deal um I have a boock that should tell me were to position it, but I don't fill like loocking it up, so do any of you guys know off hand? Let me mention that I like the performanc it gets right now so this might not be in my best intrest.

 

I love books that just sit there & collect dust! Especially useful tech books! Actually... who needs books anyway?!?!?!?!

 

Dust if you don't have a Ohmmeter then you won't be able to get the TPS right where you need it. You have to take resistance(or continuity) readings based on where the throttle is and adjust the switch accordingly. But if you're not having any drivability issues then I'd just let it be. That color smoke isn't dangerous at all. If it were too rich you'd feel a lack of performance but you said it was driving fine so don't even worry about it (well I guess you weren't too worried about it in the first place though were you ).

 

why yes, I do have a meeter. but your right I am happy with the was it performs, so I will leav it be.

nismo what do you mean about the boocks? I have so many boocks, on so many cars, and diesels, its a joke, knowledge is power, but if I don't have the boocks, I don't have some of that information, because that is too much for one person to remember. I have learned some good stuff from boocks, and I have learned some even better stuff by doing the actuall hands on.

 

I'm sorry, what exactly is a boock? Is this some new computer based book or something?

 

I was being sarcastic, because you said you have the book, but are too lazy to look it up.... in other words, it sounded like you have the books, and never use them.

oh yeah... I am also wondering what a boock is!!!

 

Ha ha I am so stupid
sorry man!