Air Dryer is affecting My engine Idle

Nothing to do with the dryer, it's probably related to your power issue. When the compressor unloads, the dyer purges at the same time. The the compressor unloading changes the load on the engine. If you have another issue, it could affect the way the engine tries to compensate for that load change.

How often does your dyer purge? When you're sleeping, your not using air, so it should hold pressure. It's common to lose some air with minor leaks, so you'll hear it purge once in a while, but it shouldn't happen too often.

 

If it is cycling that much you either have a major leak some where, or multiple little ones, or perhaps the dryer itself needs to be serviced.

 

when my dryer did that, my fan clutch had a thousand tiny holes around it. had to build up air & turn truck off, but turn key in on position, soap fan hub area & wait 5-15 min & saw all the bubbles.

 

Beside all the great advice given by the others, you may have a problem with the compressor itself.

I had 700k on truck and around 670k the compressor was really hard on the engine (ISX). When it unloaded, the engine rpm's jumps up a little bit and then settled back to idle, not what you would expect. The compressor was removed, it was hard to turn (I mean very hard with a wrench) and had a lot of lateral movement on the shaft. Replaced it with a rebuilt one and the problem went away. I did replace the governor first to make sure that it wasn't the problem and then again with the new compressor and a new air dryer cart as a precaution.

I have a truck sitting (just got it a month ago for next to nothing) which has oil on the air dryer outlet, so that compressor is going to be changed with a flush of the tanks and so on. I don't know when I will get to it, it may be a while but the oil tells me that the compressor needs new rings and valves. The previous owner's records noted that the oil consumption was high, but when dyno'ed the blowby was acceptable.

 

Fix that leak bro... it's got to be annoying to others around you.

 

and now one important quation: what engine? what year?