I have been trying to chase down a high idle, and I have not found any vacuum leaks, so I was looking elsewhere. After unplugging the PCV tube from the side of the inake, the idle speed actually went down, instead of up as I expected. I was wondering if this is normal for the PCV valve, or if it indicates that the valve is bad, and could be causing the high idle.

Additionally, the BLM for one side (not the other) was rich, not lean as I expected. I am trying to figure out which bank the right side of the Datamaster display is, so I can try to track down a leak that I may have. Which side is the passenger bank, and which one is the drivers side bank?

Thanks for your help!

 

Can anyone help me out with this?

 

the pcv is only 3 bucks anyways so if it looks a little dirty then just replace it. and when my pcv system had cracks in the lines it didnt raise the idle, it just gave it a slightly rougher idle and even worse throttle respone off idle.

i may be a newbie but i think that you may want to check the iac and tps, i believe that is what is always mentioned in idle problem threads...

if its changing the blms on one side then could it maybe be a leaky injecter or something else like that???

 

I had the same problem when I got my engine rebuilt. It was idling at 1500 RPM's. I cleaned out the IAC, which then DROPPED the idle to 800 RPM's. I recently discoverd a hole in my PCV connection. I am battling a hard start issue. I may have to buy an IAC. I'm thinking this is what's causing my hard starts. But chances are, you have to clean out or purchase a new IAC.

 

Exactly what did you pull out of the "side of the intake"? The PCV valve is in a hole on the drivers side of the intake. If you pulled the PCV valve out of the hole, it wouldn't change much... just leave the crankcase vent, from under the intake manifold open. Was the PCV valve still connected to the hose? It would still be metering air into the intake manifold.

If I recall correctly, there is no other PCV hose on the drivers side of the intake on a 95. That's where it was located in 93/94 (the U-bend, back into the side of the intake manifold), but in 95 I though (and Shoebox's 95 photos show) they routed the vacuum to the PCV from the port at the front of the intake manifold, under the TB. If you pulled that one off, its a vacuum leak.

Or, are you possible confusing the line on the passenger side, from the TB to the valve cover? Removing that wouldn't affect anything either. You would just get a little extra "unmetered" air pulled into the TB.

 

Well, what I removed was the PCV valve and the connected tube (that goes to the front of the intake manifold) from the driver's side of the intake manifold. Leaving the PCV valve attached should not cause an intake leak if the valve is good, so I figured this shouldn't really do anything. It seemed odd to me that plugging the valve would drop the idle, so I replaced the PCV valve. This did not help my idle, but it's a general maintenance item anyway.

Still searching...

 

The PCV is a double spring loaded 2-way check valve. At high intake manifold vacuum (idle), the spring holds it so it is only slightly open, and so you don't lose intake manifold vacuum. At idle, there is just a small flow from the lifter valley to the front of the intake manifold. When you pulled the PCV out of the side of the intake (and the passage to the lifter valley) but left it connected to the vacuum hose to the front of the intake, it would still have been flowing some vacuum through the PCV valve.

 

So blocking the PCV valve with my finger would have caused a drop in the idle, which it did. Which guess that means my PCV valve was probably still good. The service manual said to shake it and see if it rattles (very technically precise), which it did, but not as fast or as loud as the replacement.

I'm not really about throwing parts at a problem, but I had never replaced the PCV valve before, so i'll chalk this one up to preventative maintenance.