280Z Running Rich-- How to Fix?

[sblake01]

Is your air regulator functioning properly? That is, when you start it cold, do you get a fast idle (1100-1200rpm) that gradually lowers to normal as the engine warms?

[TomoHawk]

I think the answer to that question is no.

Mine starts fine, but idles at the (warm idle speed).

Sounds like there might be a vacuum leak or problem.

thx

[sblake01]

The point I left out earlier in this thread is that the thermotime switch/cold start valve combination only helps start the car. It only injects the fuel from the csv when you crank the car. After it starts the thermotime/csv are through. The fast idle/warm up is controlled by the air regulator. If the air regulator is not working properly, your car will run like a cold carbureated car with no choke.

[TomoHawk]

Is there another name for "air regulator?" I In the Haynes book, I see something on page 229, but it doesn't say much else.

thx

[sblake01]

On BMW's they call it the 'auxiliary air valve' but every Datsun manual I've seen calls it the air regulator. In 'Haynes' it's shown in the fuel flow diagram on pg. 222. The FSM gives a better description.

[TomoHawk]

O I C....

Basically, just another way to let air in & lean the mix. Good tip, Steven

[1975yellowBSPZ]

I also am having my 280 run very rich.

I have checked the archives and think I have some idea but would like some direction.

It smokes slightly when the throttle is depressed and has a heavy gasoline smell to the exhaust. It also with stutter or backfire if reved hard. At highway speeds on decelleration it seems rough.

My valves have been set recently.

My timing is a 0 with no room for adjustment - Might I be a tooth or 2 off on the timing chain? Could this affect my symtoms?

Also I have an aftermarket fuel rail, and I think the configuration is not right. It has a T style fuel regualtor with a guage at the firewall and the fuel return line exits there. The far end of the fuel rail has a plug in in instead of a fuel return line. Maybe too much gas is being sent to the rail and has no place to exit except thru thr injectors? It has been in this config as long as I have owned it. I am planning to add a line from the end of the fuel rail to a T below the output of the fuel regulator to see if this helps matters.

I am planning to use the information in the forum to check/adjust the AFM but want to rule out anything else major before doing so.

Any help would be great, as my car is almost drivable and I am anxious to AutoX it.

Bw

[TomoHawk]

I just got the engine decarbonized, and it seems to have helped a whole lot. When I first started it, the idle was significantly better, but it still bogged a little when I revved it. I'm not sure if it has more power, but drives OK.

[venom42]

Originally posted by TomoHawk

I just got the engine decarbonized, and it seems to have helped a whole lot. When I first started it, the idle was significantly better, but it still bogged a little when I revved it. I'm not sure if it has more power, but drives OK.

How did you go about it? Here is a link from the DSM VFAQ site (http://www.vfaq.com/index-main.html) of one method: http://www.vfaq.com/mods/MCCC.html . Although primarily for DSM cars, there is a great deal of excellent info that is applicable to all cars at that main VFAQ site.

[TomoHawk]

I had a professional guy do it.

[venom42]

Originally posted by TomoHawk

I had a professional guy do it.

Did they use the BG intake cleaner system? I had that done professionally on my first DSM, with excellent results. I am a big believer in the BG product line. Their "44k" is the best fuel system cleaner out there in my opinion. To be honest, if I had the money right now, I would just pay someone to do alot of the work I am currently planning on both the 280 and the Talon. However, seeing as how I have been hunting for a job for the last couple months, I will be getting dirty quite a bit in the near future. :stupid:

[Yarb]

Just joined the forum. 78 280Z Has-been garaged over 10 years. Running extremely rich the last time it ran. Just pulled it out and removed the tank for cleaning. Fear many of the injection components will not function any longer. Other than injectors any thoughts. I have the FSM. Owned the Z since 1984.