Hello all, hoping you can help me out with a code that is always popping up...

it is P0506 - Idle Air Control (IAC) system RPM lower than expected - Truck is a New body style 04 Lariat.

Here is the current 'status' of things: K&N Air Filter, new spark plugs (though the problem was there before), everything else pretty much stock as far as the powertrain, etc are concerned (truck is lifted though...)

Any ideas???

 

just got in from clearing the code and cleaning the MAF - we shall see what happens...

 

CEL back on again after 15 miles...

 

can you hear any vacuum leaks? PCV valve still free? Issues were there before you put the filter on? If they showed up after the you put the filter on take it off see if there is anything in the intake tract.

 

filter has been on there for a while, issue just sort of crept up.

I did notice that the foam piece that goes around the outside of the filter tray and 'seals' it to the stock intake is not 100% in place now though... could that be a cause?

 

A faulty vacuum reading would have to be after the MAF, as in inbetween the engine and the MAF not MAF and the filter.
Is the throttle body clean?
Just throwing ideas at you

 

yeah, I like ideas... keep em coming.

I have a can o' throttle body cleaner on the bench - hoping to get to that tomorrow if I can remember.

CLueless on troubleshooting vacuum problems though...

 

how does the truck run? is it just throwing the code or is it running rough too?
Did you look at the PCV valve yet?

Simplest way to check for vac leaks is while the engine is running spray some ether around the engine, and I mean just barely any, while the engine is at idle, but dont spray around where the filter is (the furthest you would go would be to the MAF). If it idles up a bit while you are spraying a certain area the leak is there, sucking in the ether.

Now ether is flamable as hell so I leave that up to you as far as safety concernes. Any spark or anything can ignite it easily.

 

A better and more readily available option is throttle body cleaner, even WD-40 will change the idle enough to show where a leak is.

Check the gasket that seals the airbox to the throttle body. The heating/cooling cycles of the engine will cause it to dry out and form a leak over time.

 

 

I have been having the same problem. This happened once before and it was the idle air control solenoid I believe is what the service tech told me. It was still under warranty at the time. It's doing this again after I installed the Diablosport 93 performance tune. I reflashed it to the original backup but the idle problem persists but it hasn't thrown the code again...yet. I am trying to find out for sure about the idle control solenoid and idle air control motor.

 

I had the same problem.......low idle, engine would die from time to time.

Read another post that suggested cleaning the throttle body with de-greaser. I removed the intake air assembly, then the throttle body (only 4 x m10 bolts). There was quite a bit of carbon build-up, and I cleaned it until it was all gone. Put everything back together and engine is back to normal. Steady idle around 600 RPM, no more stalling. Easy fix........prolly 30 minutes total.