Thread:

Idle Air Control Valve

Need help in locating the Idle Air Control Valve on a 496HO.

Thanks in advance.

Originally Posted by KahunaJuice

Need help in locating the Idle Air Control Valve on a 496HO.

Thanks in advance.

the early ones were mounted on the throttle body the newer ones our in the back of the engine with a hose running to the throttle follow the hose and you will find it theres an output test you can run with a scan tool to test it before you remove it

Originally Posted by bart@nordicboats

the early ones were mounted on the throttle body the newer ones our in the back of the engine with a hose running to the throttle follow the hose and you will find it theres an output test you can run with a scan tool to test it before you remove it

Thanks, I will look in the location as you have stated.

Originally Posted by Beer:30

I think all of the intakes were the same....it should be at the back of the top portion of the intake manifold, about where a normal distributor would be. There is a 1/2" or so rubber hose running from the throttle body back to the IAC. Just follow that. I've already replaced mine once.

If I may ask, so why did you have to change your IAC? The reason I would like to change mine is because I am being lead to belive that it is the reason why I am getting two beeps about every two to three min.

Originally Posted by KahunaJuice

If I may ask, so why did you have to change your IAC? The reason I would like to change mine is because I am being lead to belive that it is the reason why I am getting two beeps about every two to three min.

if your getting beeps your setting codes get a scan tool on it and it will tell you what it is or if in Havasu come by I will scan it for free it dosn't take long

Originally Posted by Beer:30

He's right. SCAN IT. I chased guardian beeps for several months. Finally had it scanned and it showed "starboard exh temp sensor". I looked at the temp sensor wires and the weatherpak connector was UNPLUGGED. Whoever had serviced it before I bought it had left it unplugged only. Plugged it back in, cleared the code and no more beeps.

If you haven't serviced the sea pump lately, it could be low water pressure there. That's most common for guardian. If you scan it - it will tell.

No, I replaced mine because it was surging at idle. 800 to 1500, 800 to 1500, and so on. Made it REAL HARD to dock. I changed plugs, changed the IAC, then scanned it. It showed TPS out of spec. Changed the throttle position sensor (which was stuck at 3/4 throttle) and it idled like a champ again.

That's the wonderful thing (just one of them) about EFI - if you scan the ECM, it will GENERALLY tell you what the problem is.

I had it in a shop last year in Havasu and they weren't ablt to see any code on the scan tool.

Originally Posted by Beer:30

He's right. SCAN IT. I chased guardian beeps for several months. Finally had it scanned and it showed "starboard exh temp sensor". I looked at the temp sensor wires and the weatherpak connector was UNPLUGGED. Whoever had serviced it before I bought it had left it unplugged only. Plugged it back in, cleared the code and no more beeps.

If you haven't serviced the sea pump lately, it could be low water pressure there. That's most common for guardian. If you scan it - it will tell.

No, I replaced mine because it was surging at idle. 800 to 1500, 800 to 1500, and so on. Made it REAL HARD to dock. I changed plugs, changed the IAC, then scanned it. It showed TPS out of spec. Changed the throttle position sensor (which was stuck at 3/4 throttle) and it idled like a champ again.

That's the wonderful thing (just one of them) about EFI - if you scan the ECM, it will GENERALLY tell you what the problem is.

I go into falt history to find it we have all the merc cds and g3 software but I just bought the new rinda scan tool with all the ends so I can read volvo inmare pleasusure craft ect. I hate to be shooting in the dark

Originally Posted by bart@nordicboats

if your getting beeps your setting codes get a scan tool on it and it will tell you what it is or if in Havasu come by I will scan it for free it dosn't take long

Thanks, I may need to take you up on your offer.

IAC is located on the back of the intake manifold, 2-way connector. Note that its common for these to fail and if not caught fast enough, they will damage the PCM. We do repair these, but its VERY common for them to short. If your getting a code, you first must replace the IAC, if it does not set the code, you dodged a bullet. If it sets the code again, its hurt the PCM and possibly the wiring to the PCM. Its repairable, but should not be ignored.

Dustin