still high idle

[Stranger ranger]

Ok, so I have the normal high idle issue, and to make this short, I thought I found the fix by swapping the plenum intake for reasons that didnt help anyways. Well I found that the vaccum line going into the throttle body, where the butterfly valve is, the line was broken. This line goes into the charcoal canister. Anyways, I figured that was causing the high idle, so i spliced it with a new line and made sure it was nice and tight. Changed the pcv valve and connection with a new rubber tube, made sure it was tight and didnt leak. I cleaned the air charge temp sensor and the vaccum tree, put it all back together thinking problem was solved. NOT. The dam thing would not run on its own, I'm not sure why this was but after so long, finally it would stay idling on its own, but it fluctuated back and forth for a while then FINALLY it stayed at a steady idle but, it had a really bad miss. So i figured i would drive it around for a couple miles, running it decently hard to run the bugs outta it and every time i would shift, there it was, the high idle, but its worse. How can I clean everything, replace the gasket, make sure everything is tight, and its now worse? Could I have the vaccum lines mixed up on the tree? I figured as long as the lines were getting vaccum it didnt matter where they went, but maybe i'm wrong. What else can I do now? How could it be fine before and now change it and it become worse?

 

[Nhaz]

the first thing i did was get someone to tell me if there was a error code.

it was the wrong code but it put me on the path to getting the thing repaired.

 

[Stranger ranger]

Its not throwing a code tho. and there isnt one stored because I left the battery unhooked for about 3 hours because it was dead and I was charging it while I changed the intake plenum.

 

[Nhaz]

There is a easy way to look for vacuum leaks. get a propane torch and open the valve(Dont light it!)and wave it all around your vacuum lines while the engine is running.

If there is a leak the engine will rev as the propane gas is sucked in.

Don't lean over the engine while you are doing this=>

 

[Stranger ranger]

I can see i'm just gonna have to continue to piss with till I get it right. Bad thing is, where is this miss coming from? I"m gonna change the fuel filter this weekend and throw some good 93 octane in it with some dry gas. The truck as been sitting a while and its been dam cold with little gas in the tank. when I first started it up, it would rev up nice, and then bog down and unless i kept giving it throttle, it would die out, AS IF it wasn't getting enough fuel.

 

[cllake]

Your right, it seems like bad fuel to me.

 

[Stranger ranger]

Let me ask this about my high idle. Say if I take off the IAC and plug up the holes for it, basically eliminating this actuator. IF I do not have a high idle issue any longer, is this the problem? I would assume so because if there were a vacuum leak elsewhere, would it not still suck in air from where ever it might be and continue to idle high like its been doing?

 

[Stranger ranger]

no one huh?

 

[vaderj]

when my IAC was completely dead, my motor would not idle at ALL (well, not until very warmed up that is, and when at full running temp would only idle at MAYBE 700rpm)

 

[Nhaz]

My high idle problem has been fixed with a backyard mechanic style fix.

Basically the computer is telling my iac that the engine is cold all the time. no idea why since the temp sensors are working.

So the solution was to take the computer out of the loop. we installed a toggle switch and wired the IAC inline with a power line and added a Zener (sp?) diode that passes only 7.5 volts at 10 watts.

This works so far. flip the switch on. you have a choke. as the engine hits normal temps turn it off.

And while i know this fix isn't the real solution to my high idle the underlying reason for the high idle is currently beyond me.

 

[vaderj]

a zener diode if i recall only lets volts go one way (to a certain point) but a regulator (transistor i believe) regs the volts. thats a good idea though, I dont really like how mine has the high idle either.

 

[Nhaz]

Diodes by their design only pass current in 1 direction. A zener diode also only passes current in 1 direction but with the added value of also only passing a certain amount of voltage depending on which one you bought. (they come in a huge variety)

Most diodes are pretty small I chose a 10 watt size just in case. Its most likely 5 times as large as it needed to be.

I chose a zener diode due to the fact they are less delicate then your run of the mill transistors which will go bang( or just fizz with a small puff of smoke=> ) if their voltage varies much. and voltage will vary on a vehicle.

And they are a heck of alot simpler to install.

 

[Stranger ranger]

Ya im not doing that. I would rather find the real problem and not waste my time with a reliefer fix like that.

 

[Stranger ranger]

IAC was bad. I bit the bullet and bought one and it idles PERFECT now.