low idle

[larsfrog]

My 86 305 was idling fine a few days ago, then all of a sudden it dropped about 150 RPM's. I checked the PCV valve (by rattling it) and grommet (I replaced it), I believe my EGR valve is OK but not sure (how do you check that?, the vacuum to it is good), I believe my TVS is good but did not get any vacuum/pressure (I do not know which one) to/from my carbuerator (should there have been)? I checked the fuel vapor canister line which leads to my TVS and there was no pressure there, should there be? I am banging my head against the wall becuse I have checked all of my vacuum lines a bunch of times and still can not figure it out. Is it something as easy as turning up my idle, I counted that one out because it does not make sense for the idle to change that much in one fail swoop.

 

[pauly383]

What was the weather like a few days ago ? Mine will do that sometimes for no reason sometimes , and the only difference is the outside temp and humidity ( it never drops too low , but I keep it around 550-600 in gear ). If that 305 is carbed , you need to adjust it peiodically ,no way around it /forums/images/graemlins/k5.gif

 

[larsfrog]

isn't 550 on the close side to stalling? Mine is running 550-600 in gear right now and it shakes pretty good, also when I switch from drive to reverse it does not stall but seems as if it gets close. The manual says that idle should be @650 just trying to keep up with the specs. The humidity decreased noticebly the last couple of days, is that consistant with yours? Does yours fluctuate from 650-550 often, if not how much does your fluctuate?

 

[pauly383]

Mine runs nice and smooth with a slight normal chevy tick. It doesn't stall out. I like it closer to 650 in gear but when it gets bad it still works well enough I can be lazy and let it be , even wheel with it . You want cool air with not too much moisture . I just checked and you have 68 percent humidity right now, which is funny because I didn't see any rain in your area . Mine runs best when humidity is low and temps are down . /forums/images/graemlins/k5.gif

Now your combo may be a bit different due to variations of parts . If you want just raise the idle up a little . The best way is to adjust the mixture screws in until it wants to stall, then back out until it smooths /forums/images/graemlins/k5.gif

 

[larsfrog]

I have never adjusted them before, do I do adjust one until the car wants to stall then do the same for the other? They are located near the base of the carbuerator in the front right?

 

[pauly383]

Yes , you do one side at a time, probably several times until you get it right. They are on each side on the baseplate at the front. There may be caps on them that you can remove ( usually gone after first tune up ) , a screwdriver won't fit these, you can get the tool at Napa and places like that , or like I used to before tool , is to go through all your 1/4 inch sockets until you find one that fits the hole while still going over and grabbing the adjuster screw head . Don't be worried , just keep going in and out slowly until it sounds right , its something that will come easy after awhile . /forums/images/graemlins/k5.gif

 

[larsfrog]

After driving a bit my idle is ~650 like it should be, but when I shut off my car and then restart that is when it drops to ~600-550. This did not seem to happen a few days ago, is this normal or not. If not what could be wrong? I do not want to change my idle mixture just yet, I want to see what you guys think

 

[pauly383]

I forgot to ask if you run A/C or not, and a choke. Could just be fine after it warms up. And if you run A/C thier should be a solenoid to bump up the idle . If it stays fine warm when driving, you should be ok. /forums/images/graemlins/k5.gif

 

[larsfrog]

I was wrong when I posted those RPM's above (~550-600), after I shut off the engine and restart it hovers from 450-500. But when I drive my car a short distance it idles @600 even if I put it in park then back to drive it stays @600. I do have a choke and I do have A/C do you think that one of those may be off or not functioning (solenoid)? I know this is not a big deal because my car runs but it is just odd that this all of a sudden happened. I feel as if it is something that is malfunctioning