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Discussion Starter #1
I just bought a 83 280zx non turbo and the engine runs around 2k rpms. I’ve replaced all vacuum lines that I could see that had holes or where broke. I’ve sprayed the whole intake side with brake clean with no luck. I’ve looked at bunch of stuff like BCDD, AFM, or the throttle body. I’ve done what I can and I’m stumped right now.
if theres anything that special to these cars I don’t know about it’ll be much appreciated for the information
 

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did you adjust the idle speed screw on the throttle body?

have you confirmed the throttle linkage is working properly?

have there been any mods to the fuel injection system?

have you checked the aux air controller?

Is the BCDD wire hooked up?

does the RPM change as it warms up?

how do the plugs look (lean/rich)?

when you say you have "looked at" on the bunch of stuff, what exactly does that mean? did you use the FSM to verify with testing procedures of the "looked at" stuff?
 

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Discussion Starter #3
The idle screw is maxed out at the lowest idle

linkage seems to be fine

EFI is completely stock as far as I know

I don’t know where the aux air controller is or know how to check it

also don’t know if the BCDD is hooked up or working

RPM does change as it warms up but seems to rest at 2k rpm

I’ll have to look at the plugs but I do believe it’s running a little lean, Incan hear fuel burning and popping in the headers
 

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AAR should be the 1st thing on the list. Its supposed to bypass the TB plate when cold, then slowly close up as the car warms up. check the FSM for details on what to look for (coil continuity, supply voltage, actual closure of the aperture).

I simple check would be to simply block it off so it bypasses NO air, if the rubber hose is not petrified you maybe able to pinch it off, I was never able to do that though, but I think that's in the FSM.
 

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Discussion Starter #6
Alright, thanks for the information. I’ll let you know how it goes from there. I know nothing about these cars and I’m pretty sure I’m the one of two people that has one within a 50-70 miles radius, so people that know about these are limited lol.
 

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Here’s a pic from the manual. Not sure if there is a test listed. If it gets full voltage, you could remove and test cold... but I don’t know if full battery voltage is what it receives.







Sent from my iPhone using Tapatalk
 

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think its the aux air controller or the air regulator, look at the pic that is thing you need to check, read the FSM its what control idle speed during warm up and if malfunctioning can effect idle at any time.
 

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Oops, sorry. Didn’t mean to confuse you. I was thinking of the air regulator, not the auxiliary air control. I don’t think my 79 has the AAC, just the air regulator which does taper off the controled vacuum leak to lower idle speed as it warms up.

It looks like the AAC also provides extra air at various conditions...cold temp, idle, AC on...so there is a potential there for one those to be causing it to increase the air. But you’re under most of those conditions and the main one is the temp sensor and that the actual AAC is working properly and not stuck in a open position if possible.





Here’s the info for the air regulator




You may want to check the PCV and it’s hose also


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Discussion Starter #16
I found it and took it off, there's nothing that I can see that its bad or has a line leak unless there's something inside it that I can't see. I'm replacing the lines anyways but I'm not sure what it is. I also checked the BCDD and the inside looks clean. AFM sensor is very clean and the flap for it works fine. The throttle has little to no carbon build up on it. I'm stumped as to what it could be.
 

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so you applied 12v to the coil of the air regulator and the aperture closed after a few min? then remove current it and it reopened?
Did you use a volt meter to confirm the 12 was present at the connector that plugs into the air regulator when the key is in the "on" position?

See post #10 above where the FSM was posted. The something in side you need to see is if its opening and closing. All you have to do is look thru it with power on and power off.
 

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Discussion Starter #18
How do I know it opens and closes? Is it audible? I also don't have a power probe to send 12v to anything. I only have the battery to do that.
 

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Discussion Starter #20
I believe the AAC is bad I took the vacuum line off and out my thumbs over the two holes and it would die. I was able to adjust idle by opening the valve more with my thumb. I again put the line back on and tried to pinch the line with some pliers, the idle changed every time I put it on there.

anyone know where I can find a AAC, besides in a junkyard? I seen one on eBay for like $195 but I wondered what other options there is out there.
 
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