Hey fellas, today i removed the carb and intake manifold to put in freeze plugs and new gasket due to coolant leaking through busted o-rings. I was very carefull to label everything and hook it all back up the same way it was taken off (as well as refill coolant). After hooking everything back up, i started it...after it warmed up and the choke button popped, the idle was different. Wasnt TOO bad but it sounded like it was slightly hunting. Prior to today the idle would stay perfectly steady, no jumping at all. Now it still idles pretty good but there is a slight "hiccup" or hunting (as they call it) with the idle jumping ever so slightly. IDK, maybe i was just spoiled before with the rock steady idle. I tried adjusting the idle/mixture screws back and forth and it didnt change it, so i put them back at normal setting. I thought maybe one of the cables was either too tight or too much slack when hooked back up?

Any idea what could have caused this?

 

Could be a vacuum leak. I'd recheck all the vacuum hoses again. Are you sure you got all the old gasket off?

 

It is either a vaccuum leak or the clearance of the carburator. It happened to me a few weeks ago. It was ideling up to 1500 rpms & turned out to be a vaccuum leak. I adjusted the clearance and everything is fine now.

 

I used a razor blade to scrape off all the old gasket, it was smooth as silk. Tightened everything really well. I dunno, i will go back and re-check all connections in case of vacuum leak somewhere. And just to let you know, the idle wasnt raised at all, it was just jumping a little, like 50 rpm back n forth. It smoothed out when i went back tonight and turned the idle screw up to 900-1000 rpm, but i dont want to idle that high, and as soon as i drop it back down to 850 the slight jumping starts again. From what i understand, if there is a vacuum leak, the idle will go up quite a bit and no matter how you try to adjust the idle screw, it wont go down. That isnt happening here.

 

When u say "adjusted the clearance", what do you mean exactly? Do you mean you just loosened the bolts and shifted it around, then re-tightened?

 

The general method to set idle speed is to get a smooth idle with the mixture then set the idle speed (rpm) with the idle screw. You really shouldn't have to do this after what you did. A small vacuum leak could cause a hunting idle, but if the mixture screw changes idle with a slight turn, vacuum leak is not as likely. In your first post you said it made no difference. What year is your car?

 

Its an 83 GSL. Yea im aware of how to set idle speed with both the idle/mixture screws. And slightly turning the mixture or idle screw does change the idle just like it would normally, thats why i am questioning whether its a vacuum leak. Maybe its just a very small leak, as the jumping is slight as well.

Could i have screwed up the tension on any of the cables (throttle, choke, hot-start) upon hooking them back up??

 

I've had a tiny crack in the end of a vacuum hose cause a uneven idle, but I agree it doesn't really sound like a vacuum leak. Maybe check your distributor cap terminals, rotor, plug wires and plugs. Just to be sure its not ignition related and happened to show up when you did the carb. A tight choke cable might mess up the idle, but I think the other cables would just make it idle high. Worth checking. All should have a little slack at rest.

 

Well, i took it for a drive today and it seems better. Maybe the car was just adjusting to the carb being taken off and needed some more time to run than i gave it. Thanks for the replies, appreciate it.

 

https://www.rx7club.com/1st-generation-specific-1979-1985-18/common-cause-power-loss-nikki-carbureted-models-632007/ If you notice it again.

 

Get a can of starter fluid and spray it around all your mating surfaces and vac lines. If there is a change in the idle (usually higher by a couple hundred RPM) where you are spraying the fluid, then you have a vac leak in that spot.

 

Wow, that might just explain it, i must have missed this in the search i did. I may just have tightened that damn accelerator cable tad too much. I will go out today and check the acc cable and the "teeter totter" while im at it. Thanks Jake