Please help with very high idle 3500-4000

[nolanswiger]

the truck always had a higher idle (maybe 1000 don’t know don’t have a gauge) but after replacing some items and taking emissions items out it has run so much higher, Ive gotten a little in over my head and any help is much appreciated. I’ll supply some photos so that you can see what I see.

1986 Chevy c10 305 recently started after being parked for 14 years.

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[Ricko1966]

Need more info. What did you do? Changed some items and removed some emissions. That tells us very little did you reroute the vacuum to the distributor? What components did you replace,what did you eliminate, and why? Have you checked for vacuum leaks? Things that come to mind first are,you plugged the distributor into manifold vacuum and need to adjust idle. Or vacuum leaks because I'm assuming you undid,rerouted a bunch of vacuum lines. If you can't name the emissions components or really any component and describe how they function and what they do,you shouldn't eliminate them without knowing that first. Looking at one of your pics,the egr valve has a screw in it. Total unnecessary because the egr valve makes no vacuum,it gets its vacuum from the carbureator. You should have working EGR. Better Mpg,less knock sensitivity,and the ability to run more timing. The bowl for the carbureator is plugged and shouldn't be. I'm assuming you undid everything on the charcoal cannister,there's a whole new bag of worms to deal with. I suggest you hook everything back up as per factory diagram. Then ask questions on how to eliminate things and what the possible consequences are. GM didn't have morons designing this stuff. Hmm looked at your pictures some more,next I would suggest you just start cutting wires everywhere with no idea where they go or what they do. Okay don't do that but you get my point?

 

[MyTruckIsBetter]

Bust out the vac gauge and hook it up to your manifold vacuum port on the carb and see how many pounds your pulling should be in the ballpark of 15-20 psi vac. As Ricko suggested you may have a couple of vacuum leaks which will affect the idle. Also if you pulled emissions controls.... make sure your PCV valve is still connected (red line) those screws (in green) will not seal a vacuum leak you need to get an actual plug/cap (golf tee will work better in a pinch ) but it also looks like you have something else disconnected in purpled and I'm not sure what that is yet... put your finger on it and see if it pulls a vacuum it may be another PCV port which will need to be routed to the other PCV port that you have in the front right of your engine.


Also curious what spark wires are you running? I haven't had very much luck with getting the correct size from NAPA

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[Ricko1966]

Bust out the vac gauge and hook it up to your manifold vacuum port on the carb and see how many pounds your pulling should be in the ballpark of 15-20 psi vac. As Ricko suggested you may have a couple of vacuum leaks which will affect the idle. Also if you pulled emissions controls.... make sure your PCV valve is still connected (red line) those screws (in green) will not seal a vacuum leak you need to get an actual plug/cap (golf tee will work better in a pinch ) but it also looks like you have something else disconnected in purpled and I'm not sure what that is yet... put your finger on it and see if it pulls a vacuum it may be another PCV port which will need to be routed to the other PCV port that you have in the front right of your engine.


Also curious what spark wires are you running? I haven't had very much luck with getting the correct size from NAPA

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In red circle is his crankcase filter so he's just sucking dirt into the engine,the screw in green in the egr,the egr has no vacuum on its own anyway so no plug neccesary.The red line is not correct the valve cover end is pcv,but the carbureator end of the red line is the bowl vent,which should go to charcoal canister,but shouldnt be plugged. I used your post in quote because you put green and red circles in things,which made it easier for me to describe things. I'm not going to critique it all. Put it back like it belongs,learn what things do and let's start over.

 

[mtbadbob]

Once you get the vac lines & PCV hooked up & in the right order, invest in a can or 2 of carb cleaner! If it's been sitting that long, even plan on a carb kit & rebuilding it. An electric, adjustable choke needs to be set properly for start-up & smooth idle.

 

[nolanswiger]

Once you get the vac lines & PCV hooked up & in the right order, invest in a can or 2 of carb cleaner! If it's been sitting that long, even plan on a carb kit & rebuilding it. An electric, adjustable choke needs to be set properly for start-up & smooth idle.

Thanks for the advice it’s my dads old truck and trying to fix things I’ve done before, ive only worked on smaller engines so help like this is much appreciated.

 

[nolanswiger]

In red circle is his crankcase filter so he's just sucking dirt into the engine,the screw in green in the egr,the egr has no vacuum on its own anyway so no plug neccesary. I used your post in quote because you put green and red circles in things,which made it easier for me to describe things I'm not going to critique it all. Put it back like it belongs,learn what things do and let's start over.

In red circle is his crankcase filter so he's just sucking dirt into the engine,the screw in green in the egr,the egr has no vacuum on its own anyway so no plug neccesary.The red line is not correct the valve cover endbis pcv,but the carbureator end of the red line is the bowl vent,which should go to charcoal canister,but shouldnt be plugged. I used your post in quote because you put green and red circles in things,which made it easier for me to describe things I'm not going to critique it all. Put it back like it belongs,learn what things do and let's start over.

Yeah I definitely messed up thanks for all the advice the truck was already screwed up badly before all the mess I created. Again this is much appreciated.

 

[nolanswiger]

Bust out the vac gauge and hook it up to your manifold vacuum port on the carb and see how many pounds your pulling should be in the ballpark of 15-20 psi vac. As Ricko suggested you may have a couple of vacuum leaks which will affect the idle. Also if you pulled emissions controls.... make sure your PCV valve is still connected (red line) those screws (in green) will not seal a vacuum leak you need to get an actual plug/cap (golf tee will work better in a pinch ) but it also looks like you have something else disconnected in purpled and I'm not sure what that is yet... put your finger on it and see if it pulls a vacuum it may be another PCV port which will need to be routed to the other PCV port that you have in the front right of your engine.


Also curious what spark wires are you running? I haven't had very much luck with getting the correct size from NAPA

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Thanks for all the advice! The spark plug wires were from rock auto they are ngk I don’t know a part number im currently away from the truck.

 

[Ricko1966]

Yeah I definitely messed up thanks for all the advice the truck was already screwed up badly before all the mess I created. Again this is much appreciated.

Okay look at your factory sticker put everything back the best you can. Then ask questions about the things you can't,and the work arounds. Do still have your stock air cleaner some where?

 

[nolanswiger]

Bust out the vac gauge and hook it up to your manifold vacuum port on the carb and see how many pounds your pulling should be in the ballpark of 15-20 psi vac. As Ricko suggested you may have a couple of vacuum leaks which will affect the idle. Also if you pulled emissions controls.... make sure your PCV valve is still connected (red line) those screws (in green) will not seal a vacuum leak you need to get an actual plug/cap (golf tee will work better in a pinch ) but it also looks like you have something else disconnected in purpled and I'm not sure what that is yet... put your finger on it and see if it pulls a vacuum it may be another PCV port which will need to be routed to the other PCV port that you have in the front right of your engine.


Also curious what spark wires are you running? I haven't had very much luck with getting the correct size from NAPA

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Found the wires they are $21 on rock auto the part number is ngk 51355

 

[nolanswiger]

Okay look at your factory sticker put everything back the best you can. Then ask questions about the things you can't,and the work arounds. Do still have your stock air cleaner some where?

Yes I do.

 

[Ricko1966]

Bust out the vac gauge and hook it up to your manifold vacuum port on the carb and see how many pounds your pulling should be in the ballpark of 15-20 psi vac. As Ricko suggested you may have a couple of vacuum leaks which will affect the idle. Also if you pulled emissions controls.... make sure your PCV valve is still connected (red line) those screws (in green) will not seal a vacuum leak you need to get an actual plug/cap (golf tee will work better in a pinch ) but it also looks like you have something else disconnected in purpled and I'm not sure what that is yet... put your finger on it and see if it pulls a vacuum it may be another PCV port which will need to be routed to the other PCV port that you have in the front right of your engine.


Also curious what spark wires are you running? I haven't had very much luck with getting the correct size from NAPA

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Best generic plug wires for a small blockbchevy are 1975 1 ton 454 yea that's not the application but just remember it. Anyways 90 degree HEI ends at distributor Straight boots and just the right lengths.

 

[Ricko1966]

Yes I do.

It will provide filtered air to the passenger side valve cover and cold air intake for the engine. The chrome filter you have you could put a fitting in it and vent the valve cover to it,or buy a valve cover vent, but your chrome filter is always going to suck hot under hood air. Pull the vacuum hose off of the distributor temporarily and put a screw in it. Does your idle come down.?

 

[nolanswiger]

It will provide filtered air to the passenger side valve cover and cold air intake for the engine. The chrome filter you have you could put a fitting in it and vent the valve cover to it,or buy a valve cover vent, but your chrome filter is always going to suck hot under hood air.

Okay good to know thank you very much.