New Problem! Car will only Idle now

[Zachary Lawson]

So my car was running pretty decent, just had a rough idle that I was working on. So I tried a few things like, screwing the air screw all the way in to find air leaks. Spraying the intake with brake cleaner (also in the air screw hole). After those troubleshooting processes,the car won't hardly even start now. It will only run at idle roughly. When you give it any sort of gas it dies. It seems to me like it overloading now. Sometimes it won't even start unless you unplug the fuel pump. Anyone have any ideas off the top of there head?

[Zachary Lawson]

It's a 1978 280z, Stock everything.

Update:

So when I unhook the line from the air regulator It runs at about 6k or 7k rpm, but runs like it suppose too. I can give it gas and it will open up even more. Also If I take the air screw all the way out, it seems to improve it somewhat. It's acting like it's not getting any air. I can take the boot off the AFM and it runs at a very fast idle. I can put my hands around the AFM like how the boot should be. And the Engine runs like it's suppose too. If I unplug the cold start valve, should the motor change?

Edited January 17, 2013 by Zachary Lawson

[Zed Head]

Clogged air filter?

[Zachary Lawson]

Clogged air filter?

You think a clogged air filter would make it pretty much not run?

Update:

I just checked the air filter, It's fine. Thanks for the input though.

Edited January 17, 2013 by Zachary Lawson

[Zed Head]

You said it ran well with the hose between the AFM and the air filter removed. The only thing between the AFM and the "air" is the filter and the plastic tube to the air intake point. Did you check the rest of the intake system.

Maybe you meant the hose from the AFM to the throttle body? If so, it sounds like your AFM vane is stuck closed.

[Zachary Lawson]

Yeah I was referring to AFM to the throttle body. When I remove the boot, I can try to close the gap with my hands to imitate the boot. It runs very close to how it should. I don't think the flap is stuck closed.

[Zed Head]

The things that you tried that raised the idle that made it run better all leaned out the mixture. Removing the AAR hose, taking off the AFM boot (AFM signal disappears), taking the air screw back (bypasses the AFM vane). Somehow you've made things too rich. Did you adjust the AFM spring? Accidentally knock the coolant temp sensor connector loose? Raise your fuel pressure somehow?

You might also have fouled some plugs. Brake cleaner is not designed to burn, like carb cleaner is. The old brake cleaner won't burn at all, I don't know about the new "green" stuff.

[Zachary Lawson]

The things that you tried that raised the idle that made it run better all leaned out the mixture. Removing the AAR hose, taking off the AFM boot (AFM signal disappears), taking the air screw back (bypasses the AFM vane). Somehow you've made things too rich. Did you adjust the AFM spring? Accidentally knock the coolant temp sensor connector loose? Raise your fuel pressure somehow?

You might also have fouled some plugs. Brake cleaner is not designed to burn, like carb cleaner is. The old brake cleaner won't burn at all, I don't know about the new "green" stuff.

The funny thing about it is that it run fine until I just adjusted the air screw all the way in. Then after that it just ran awful. That's pretty much all I did. You think maybe I locked the flap closed? No I didn't adjust the AFM spring or mess with the fuel pressure. I'll update you with some test tomorrow. Thanks for all the help.

[Zed Head]

You think maybe I locked the flap closed?

More likely that it's stuck open, causing the ECU to supply more fuel. You can check by looking at the bumper for the damper weight under the black cover on the side of the AFM.

[Zachary Lawson]

Update:

I was way off! I figured out by accident that my ECU is losing connection. The car is running great now. Thanks for all the input Zed Head.