280z dies when ac is on

[bandoni]

hi i have a 78 280z which i just bought, I just installed new injector connectors ( i just cut off the old ones and connected the new ones, someone on zcar.com told me that it didn't matter which wire went where) these are the connectors i used

well it seems to run fine now but when i turn on the ac whilst i am driving when i de-accelerate it stalls and dies, like i turned the key over. so i came home and turned the ac on while it idled, it was fine idling normal soon as gave it a little gas, it just dies. anybody got any ideas?

[bandoni]

here is a video of the problem as well hope this helps.

(yeah its got a zx steering wheel but it is a z)

<embed style="width:400px;height:326px;" type="application/x-shockwave-flash" src="http://video.google.com/googleplayer.swf?docId=-7800035372873835247&hl=en" id="VideoPlayback" align="middle" quality="best" bgcolor="#ffffff" scale="noScale" salign="TL" FlashVars="playerMode=embedded"></embed>

[240Z-Fan]

My first thought is that the idle speed is too low. If it is idling at 400-500rpm it may not handle the extra load of the AC very well.

I think the idle speed may need to be in the 650-850rpm range. Find out the correct idle speed and adjust accordingly. It should be on a sticker attached to the hood. Or make an educated guess and see if it solves the problem

I recommend checking the timing too to be sure it is correct too.

I can't remember if 280z's had something to bump up the idle when the AC is on; surely somebody else will know this answer. Anyway, this could be coming into play too if it isn't working right.

Al

[DatsunZsRule]

Yes, there is something to bump up the idle for the A/C They are the magnet valves located near the pass. side fender in the engine bay. Sblake seems to be good with A/C's and I'm sure he will chime in soon.

Your idle is way to low though which is part of the problem. If you have an Automatic trans. the idle should be @ 700 RPMs with transmission in Drive. On a manual transmission model, the idle should be at 800 RPM's

[76Datsun280z]

In the video, your idle sounds to low. 400rpm as you say for the idle is way to low, especially running the a/c which will take away more horsepower, therefore lowering the idle even more which will make it stall. Your idle should be around 850rpm. Raise the idle up on the idle adjust. screw and let us know what happens.

[bandoni]

thanks for the quick replies, I thought that might be what is going on. So can someone point me in the right direction of how to set the idle speed? all your help is much appreciated.

[76Datsun280z]

The quick and easy way to do it is by sound and checking the tach. rpms to get it in that 800 range. I'm know there's a more acurate way of doing it to get an exact rpm set, but if you're looking for the fast way to do it, that's pretty much how you do it.

[sblake01]

Did you have the problem before you changed the connectors? I ask though the injector connectors shouldn't have anything to do with the AC. Yours appears to have factory air which would have a fast idle circuit for when the AC is on. Mine has aftermarket installed AC w/no fast idle circuit. Alot of things happen with the fast idle control device as well as the mode door actuator and air intake door actuator, that involve vaccum when the AC is switched on on the factory air cars. If you have an FSM, trace through the vaccum line routing as well as trouble shooting the items involved in those systems. Vaccum leaks could cause the problem you're having and there are many places they can occur when the factory air is turned on. If you don't have an FSM, you can download one here here: http://carfiche.com/manuals021/cars/. If it's not available at the time check back later. I know your car is a 78 but they only have a 77 FSM available. It will work, however, for your AC system.

[bandoni]

no problem before i changed the injector adapters, i will download the fsm when it comes available. i will work on it tomorow when it is light and keep you all posted on what i discover. thanks

mark

[sblake01]

I see there's been a few posts in the time it took to compose mine. The reason I don't think problem exitsts simply because of low idle speed is if that was the case, it wouldn't die out when you revved it up.

[DatsunZsRule]

Before you replaced the connectors, what did it idle at?

Without the air on and it's idling, do you notice a miss in the engine?

What did you use to connect the new connectors to the existing harness?

Just trying to figure out other possible causes.

[bandoni]

oh ok it idled about the same before i changed them about 400 to 500 rpm when warm. i noticed no miss although it does idle a little rough. i couldn't get my solder gun to work (its really old:( ) so i just twisted them together and put some wire nuts on them till i get them soldered together. (if i did that wrong any suggestions on how i could install them)