idle cavitation
FTE Chapter Leader
Joined: May 2006
Posts: 12,334
Likes: 1,309
From: Central Mississippi
Just an observation...
Cavitation usually referrs to the foaming of a liquid, either coolant or oil due to improper levels and the inability to pump the same. Too much or too little.
The IAC valve should not have anything to do with causing such.
Cavitation usually referrs to the foaming of a liquid, either coolant or oil due to improper levels and the inability to pump the same. Too much or too little.
The IAC valve should not have anything to do with causing such.
Elder User
Joined: Jun 2006
Posts: 805
Likes: 3
If there is significant carbon build-up on the backs of the throttle plates, that will affect idle. Simply removing and cleaning the IAC won't quite get you there. If the orifices on either side of the plates for the IAC are gummed up with deposits, it will affect how well the IAC does it's job. There should be a couple small holes in the throttle plates as well. Make sure they're clean and clear of deposits. I removed the entire throttle body to clean it properly.
Before:
After:
If you'll check out my gallery, you'll see the rest of what I found that gave me a very raggy idle, lean-miss, and pinging like there's no tomorrow. Once you get the throttle-body off (15 minutes), you're about 20 minutes away from having the whole upper intake plenum off (depending on the condition of the big tubing nut on the bottom of the EGR). The nut on the bottom of the EGR will be your biggest challenge, because that bugger is TIGHT!!!. USE A WRENCH THAT FITS, or you WILL be hunting a rather rare piece of tubing if not a replacement 1234 exhaust manifold. The upper intake gasket set is only about $15, and well worth the maintenance. Throw another $16 at that, and you've got two sets of o-rings for the injectors. The gasket set includes the IAC, TB, and Plenum-manifold gasket. It does not include the manifold-head gaskets, nor the cam-valley seals. If you want a new EGR gasket, you'll have to purchase that separately. It's a graphite flake/fiber/steel gasket, so you should be able to re-use it fairly easily. If I had the Felpro number's I'd post 'em. But who knew I'd be telling someone else that incompetent stealerships can't find what a novice/hobbyist mechanic can.
Before you go running out to buy a bunch of expensive electronic code readers, etc., take about $2 and go to Office Depot and buy a box of paper clips. That's 100 code readers in one box. I get to use a brand new one every time I wanna read codes. Take the rest of the $50/$60 you were going to use on the code reader and buy a vacuum gauge, and a fuel pressure gauge. These two items are your friends on our vintage trucks. You may have to use up some of your code readers (paper clips) as fuel pump testers. Same plug used for reading codes has a pump test input too. It just bypasses the ECM output to ground the coil of the pump relay. Be advised, though, you will get a fuel pump relay code if you use that input. I got it EVERY time I ran the fuel pump from there. Kinda scared me the first time I saw the CEL right after determining every thing was OK, and then running a ffuel pressure test.
Minor driveability issues can be VERY expensive if you just start throwing parts at them. Sometimes, you may have to buy a few less sophisticated tools first to correctly diagnose the problems.
They symptoms you're chasing are typically vacuum leaks.
Before:
After:
If you'll check out my gallery, you'll see the rest of what I found that gave me a very raggy idle, lean-miss, and pinging like there's no tomorrow. Once you get the throttle-body off (15 minutes), you're about 20 minutes away from having the whole upper intake plenum off (depending on the condition of the big tubing nut on the bottom of the EGR). The nut on the bottom of the EGR will be your biggest challenge, because that bugger is TIGHT!!!. USE A WRENCH THAT FITS, or you WILL be hunting a rather rare piece of tubing if not a replacement 1234 exhaust manifold. The upper intake gasket set is only about $15, and well worth the maintenance. Throw another $16 at that, and you've got two sets of o-rings for the injectors. The gasket set includes the IAC, TB, and Plenum-manifold gasket. It does not include the manifold-head gaskets, nor the cam-valley seals. If you want a new EGR gasket, you'll have to purchase that separately. It's a graphite flake/fiber/steel gasket, so you should be able to re-use it fairly easily. If I had the Felpro number's I'd post 'em. But who knew I'd be telling someone else that incompetent stealerships can't find what a novice/hobbyist mechanic can.
Before you go running out to buy a bunch of expensive electronic code readers, etc., take about $2 and go to Office Depot and buy a box of paper clips. That's 100 code readers in one box. I get to use a brand new one every time I wanna read codes. Take the rest of the $50/$60 you were going to use on the code reader and buy a vacuum gauge, and a fuel pressure gauge. These two items are your friends on our vintage trucks. You may have to use up some of your code readers (paper clips) as fuel pump testers. Same plug used for reading codes has a pump test input too. It just bypasses the ECM output to ground the coil of the pump relay. Be advised, though, you will get a fuel pump relay code if you use that input. I got it EVERY time I ran the fuel pump from there. Kinda scared me the first time I saw the CEL right after determining every thing was OK, and then running a ffuel pressure test.
Minor driveability issues can be VERY expensive if you just start throwing parts at them. Sometimes, you may have to buy a few less sophisticated tools first to correctly diagnose the problems.
They symptoms you're chasing are typically vacuum leaks.
