excessive idle speed

my 87 4.0 is idleing very high, about 1200 rpm in park or neutral and 1000 rpm in gear. I have an Oil Catch can rigged up for the CCV line that goes beween the rear of the valve cover and the intake manifold, and I was wondering if this has anything to do with it. I have just recently had the throttle body and the fuel injectors cleaned, but this did not help, also I am not able to find any vaccum leaks that could be causing this. Just on a side note someone had a very good link on how to test all the sensor on a Renix with a multimeter and I managed to loose the link, so if anyone still has it I would appriciate it, I was kind of thinking it might be the IAC causing this but I am not sure.

The CCV tube should not be split. You should put it back as a single line with no breaks in it. Check for any clogs in the manifold fitting and in the orifice in the valve cover grommet. If you are gonna re-use your old CCV tube, make sure its cleaned out as well.

If you need a catch can for oil, split the front hose which is a breather tube assembly and run your catch can off of this line.

The stock CCV tube has been replaced by a thicker plastic tube going to an oil catch can. Another tube goes from the Catch can to the intake manifold. The orifices were cleaned out recently (maybe 2 months ago) when we installed the catch can. I don't really see how I could run the can off of the front tube since the system would have to be backed up inorder for the oil to enter that tube any way. The front tube is used to suck fresh air in from the Airbox. This air is used to help scavenge the blowby inside the valve cover through the rear CCV tube and into the intake manifold where it is reburnt. From what I know, the factory rear CCV tube due to its small diameter usually plugs up, so instead of the blowby being drawn to the intake manifold, it forces its way out of the front tube, making the air filter box into the oily mess. Since I isntalled the oil catch can the Airfilter has been dry as a bone, and this high idle was present before the installation of the can. It has gotten higher latly so I've decided I want to do somthing about it.

Heres that write up on all the renix sensors and how to troubleshoot.
http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

Mine was doing that after a fresh rebuild. Turned out to be bad manifold gasket in my case, leaking from the bottom side.

Have you checked torque on manifold bolts?

Nevada City Sparky said:

Mine was doing that after a fresh rebuild. Turned out to be bad manifold gasket in my case, leaking from the bottom side.

Have you checked torque on manifold bolts?

Click to expand...

AHHHH after doing a good search (Hello search function) I am afraid this is my problem also.I just rebuilt my head as well, installed everything, and theres a high idle(1100-1200) as well. I REALLY dont like that bottom half of the manifold.
However, i am afraid thats where the leak is coming from since i couldnt get a real good turn on those bolts.....My hands are too large ( but my wife doesnt complain ) It was fine in the morning, but it was also very cold out. The metal expanded enough i think.
I guess its onto operation impossible bolt.