engine lag

[Hardwyre]

Bad vacuum advance = bad mileage.

Bad vacuum hose = bad performance.

It sounds like you found the issue, so props to you. Remember, any air making its way into the engine past the AFM messes up fuel metering. In the case of carbed rigs, same thing.

[JohnnyP]

Thanks for advice guys, you all pointed me in the right directions!

[JohnnyP]

So…..

I went out to buy a new piece of hose that runs from the carbon canister to the vacuum advance and throttle valve. I put it on, expecting to help out the "lack of power" issue but instead…no better. The new hose is ever-so-slightly bigger than the old one. I taped up the T connector, and used little screw clamps on all the fittings, even the T connection.

The car still lags on startup and whenever the accelerator is depressed. When the bad hose was on there I simply put electrical tape over where I thought the bad spots were (only for a temporary fix). I figured a new hose would do the trick but the problem has come back to haunt me! Anybody have any suggestions on where to start? Here is what I've done so far:

Ran through the FSM E.F.I troubleshoot for "lack of power"

Tested vacuum advance

Replaced the vacuum advance hose

[Z Tyler Z]

I have a 1976 280z. The car fires up right away, but if I give it some gas (within the first few seconds of the car being on) it makes a sort of sputtering noise, like the car is about to die. And when I put it in gear and give it some gas, the car doesn't respond like it should. I guess the easiest way to describe it is it feels like when I press on the accelerator a good amount, the car doesn't go as fast as it should, the car doesn't really get up to speed. Im not sure where exactly to start with problem. Dirty fuel injectors? Bad fuel pump? Clogged fuel lines? I just put a bottle of fuel injector cleaner in the tank this afternoon, and ran it for a while. Hoping to see some result there. If anyone has had a similar experience with a problem like this, your advice would be very appreciated. Just trying to get this Z back on the road. Thanks alot everyone

John

After plugging off my Cold start my car no longer does what your cars does. My car use to also have a dip in the rpms when I started it. I assume the cold start was flooding it until the ecu corrects it (or something along those lines) If I were you I'd plug it off and see if anything changes. Idk if there's a test for a leaky cold start injector.

[JohnnyP]

How did you plug your cold start?

[Z Tyler Z]

Put a bolt where the fuel rail splits off for the cold start valve and tightened it down. I'll take a picture tomorrow if you don't get what I mean. It doesn't leek and seemed to fix most problems.

[JohnnyP]

Can anybody recommend a good method of plugging the cold start valve?

Edited June 29, 2010 by JohnnyP

[JohnnyP]

I don't mean to beat a dead horse over this cold start issue, but I just want to make sure I'm doing this right. Z Tyler Z is this what you did to plug your cold start (or can anyone tell me if this is the improper method? If so which is the correct one?)

Thanks for everything guys/gals, everyone here is beyond helpful!

John

[Z Tyler Z]

Did you just tighten that down or did you stick a bolt in there then tighten it down I can't tell by the pictures. I attached a picture of what I did (been meaning too for a couple days now my bad).

[JohnnyP]

I didn't even think to do that :stupid:

I threw up the pictures just because I wanted to make sure I didn't mess anything up! Thanks for the picture, it really helped!