Fix this car...

[JB]

Anyway of testing it? Where is it located?

[robertf03]

I think its on back of the engine. You might be able to test it with a volt meter, depending on how fast it responds. 3 pins, 5V+, 5v-(common to chassis ground) and signal. If you tap into the signal wire and crank the voltmeter should register something. I think you can stick a paperclip between the weatherpack grommet and wire and it will touch the pins.

If you wanted to get crazy with it you could chop the end of a speaker/microphone jack, plug it into your computer and tap the ends of the wire into the plug, use one of those sound recording programs that shows the noise waveform and see if there are a bunch of square shapes showing up. It would be a good idea to turn the volume down for this.

[Graystroke]

pull a plug and ground it to check for spark?

[JB]

My f150 started to throw a code yesterday, PO506, which said IAC valve duty cycle lower than expected. It will start to idle low, like it is going to die, then come back up. Sometimes it will die. Once on the road, everything is fine. Can I assume a new IACV or at least a good cleaning will fix the issue? If I let it idle, and unplpug the IAC, what should happen?

[uglyota]

radiator cap?

[Seth]

Completely diff motor, but I had that same type code throw on the white truck, and replacing the sensor fixed it. I might have bought it from you even?

[eight]

IAC is a stepper motor. If you unplug it it will stay in the same position. If engine is idling when you unplug it, idle speed should stay the same.

[Graystroke]

IAC is a stepper motor. If you unplug it it will stay in the same position. If engine is idling when you unplug it, idle speed should stay the same.

until you turn on your lights and ac and load th motor. pull it and clean it and the place it screws in. clean the valve seat too.

[JB]

The IAC is part of the electronic throttle body. The TSB says I need to replace the TB. $172 online, or $280 at the dealer.

[Graystroke]

clean connector first and make sure it's not corroded or has bad connection.

[JB]

new throttle body and a reflash and she's good as new.

[JB]

05 Chevy K1500 5.3 77k miles.

He just bought it from a guy who we both believe was not trying to screw anyone over, but two weeks in, it has 2 seemingly major issues.

1) Loud ticking from top of motor. I have not heard it, but he says it sounds like a lifter is loose. Does it especially when its is cold, but now is doing it enough to where he doesnt want to drive it. Is there a common issue on these motors that might relate?

2)Coolant loss. He put over a gallon in the overflow, drove from SA to BCS and back, and overflow is dry. Hasnt overheated. He let it sit in the driveway for an hour and sees no leaks. Changed the oil, and it looks fresh and new.

Any ideas with the vague descriptions I gave?

[Seth]

Coolant loss I would guess is leaking manifold gaskets, though I remember it being more of an issue on earlier motors.

Ticking sucks, bc all he can do is drive/run it while putting various snake oils through it, or tear it apart.

[Fredo]

On the ticking issue. Have him turn the a/c off and see if it still does it. Those have a secondary drive belt for the a/c compressor and sometimes they start to come apart and make some really odd noises that sound like they are coming from other places.

Now saying that, if the coolant loss is related to the noise, then it might be a head gasket. Seth, the LS based vortecs don't have coolant running through the intake manifold, so that won't be the problem. I would check the water pump. I can't remember if the weep hole is visible from underneath or not, but that would be where I'd start.

[JB]

There is TSB about the mysterious coolant leak. Apparently it calls for some $12 AC Delco coolant pellets or new heads. Great.