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Well, in theory, a vacuum leak wouldn’t go away when you shut the car off. I would start by inspecting/cleaning the throttle plate. I had an old Camaro with a Quardrajet that had some build up around the throttle butterflies in the primaries. It did something like this a couple times. Some carb cleaner took care of it.
Is there any CEL’s?
You could check the IACV by tapping it with a screw driver and see if the idle starts to act up. Also, KOEO with the IACV removed, you can sometimes see the pintle inside move.
+1 on Beefy’s post too.
Check out this video –
http://www.youtube.com/user/briansmobil … XBogMCgIvY
It may shed some light on your issues.
i sprayed the throttle linkage off. I was going to pull off the air intake to spray the throttle plate tomorrow. I was definitely not thinking it was a vacuum leak because it is intermittent. There is a CEL. I checked it the other day for another issue. It states 02 bank 2/2 heater circuit malfunction. That was before this problem arose though. I am going to check it tomorrow to see if a new code set. I will probably check manufacturer codes. Thanks for the video. Definitely a good tip.
It’s not often I hear of an IAC causing a condition like this, normally it would cause a problem at idle NOT driving down the road, in fact most times I find it to be a mechanical issue with the throttle linkage. I would recommend removing the linkage from the throttle and checking to see if you have any resistance in the throttle linkage or the throttle itself, I don’t recommend lubricating the linkage (especially if it’s a cable) if you find that to be the problem but rather replace it with new as it can be a serious safety issue.
If still no luck check for worn wires or rubbing. I had a shorted wire on a car once that caused it to randomly idle at 2500, and sometimes take off in traffic, so I made it a habit of shifting into N when slowing down.
Once I located the short (sensor wire near the exhaust manifold) I taped it up and the car was all better.
I only found one issue….thre was a downstream o2 sensor code…turned out all wires were torn apart….he hit a cone on the freeway…but I am thinking maybe the wires from the harness end were rubbing the crossmember right below it. I am taking it to an exhaust shop tomorrow because the o2 sensor threads were welded to the bung. So it needs a new bung installed. We will see how it runs after that.
So it turned out that the cruise control cable was broken and when you step on the gas, the cable would get caught on the throttle linkage keeping the rpms at about 4k. They don’t make the cable anymore…so Pick N’ Pull it is.
Quoted From Six6vetteguy:
So it turned out that the cruise control cable was broken and when you step on the gas, the cable would get caught on the throttle linkage keeping the rpms at about 4k. They don’t make the cable anymore…so Pick N’ Pull it is.
Nice job on figuring out the issue!
Let us know how the search for that part goes. I would also check online too, even better if you know the OEM part number.
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