As many of you may know, recently I took off the upper intake manifold and did some work on the truck. I cleaned the throttle body (and as much as I could in the manifold itself), replaced all the vacuum lines (reused the old fittings), and rectified the broken check valve situation next to the smog pump. Ever since then it's been idling rough when cold. It seems to idle at 400-500 and rev up a bit periodically like it's struggling. It also seems to lack power (more than usual) and won't move at idle when in drive or reverse, like how you would idle out of a parking spot. I just pulled the codes:
KOEO: 111
CM: 111
KOER: 412 (cannot control rpm during KOER high rpm check
538 (insufficient RPM change during KOER dynamic response test OR operator error)

Can anyone make sense of this? I suspect the old vacuum fittings, the IAC, or the TPS or some combination of them

 

I'd agree with you on the Vacuum issue. Do you have a vacuum guage? Is it possible you have a vacuum line leading to to the wrong fitting (ie, an input to an output)? It's easy to do with so many vacuum lines on engines from 80 on (I miss my old '65 F100...).

There is also the possibility of a poor gasket fit on the intake manifold after replacement (). Spraying a little WD40 around the intake where it meets the mating surfaces might help determine that. (if idle gets better...)

 

I don't have a gauge. I was pretty **** about putting the new lines exactly where the old were. I had a bit of a mixup with the red and black lines at the carbon can, but my understanding is that would cause problems in the emissions system only since that's the only thing downstream of the carbon can in the vacuum system

 

I see you're in beavercreek, I'm just up 675 and 4 here in springfield

 

anyone able to advise here? I've heard you can test the vacuum system by spraying some starter fluid on the lines/fittings at any suspicious place and if the idle changes there is a leak. Any idea on how I would check the IAC?

 

so what was the need to take the intake off in the first place?

 

to get to the check valve which was behind the intake next to the smog pump. I hate to think of trying to do it without removing the intake, I bruised enough knuckles even with it off >.< also provided a good opportunity to look at the vacuum lines

 

what did you replace the lines with? the hard plastic colored lines, or black rubber lines?

 

hard plastic black lines, I differentiated with colored tape

 

do you know where the IAC is. if you do, start your truck and unplug it. if you notice a difference in idle that would be your problem.

if it was a vacume line leak it would cause high idle more likely than low idle.