I was out in Colorado at the CAA this past week - during which I (and several others) noticed an unusual idle issue that developed: if you push in the clutch and rev the engine, the engine RPM's raise up, then drop to around 1K, then raise up to 1.5K to 2K, drop back down, raise back up and so on. Sometimes it will only do it once before dropping to normal idle RPM, other times it will oscillate several times.

Now that I'm back in OKC (1200 ft. altitude), I don't see the problem at all.

Several thoughts on the cause of this problem:

- the altitude is messing with the sensors and causing the computer to 'hunt' for the proper idle

- I did a LOT of engine braking in the mountains - more than I've ever had to do before...maybe this messed with how the computer 'learns' driving habits and caused it to have difficulty finding proper idle speed

- I didn't get a chance to try a throttle reset while I was out there...

Any ideas?

 

....x..2.....

 

I have had both my 6's out in that altitude and had no issues at all..... I was driving normally though....

 

Check for vacum leak. I had the vacum hose to the heater disapear and the idle was fine with the A/C on but when it was off, the engine would idle high if I put the cluch in coming to a stop. Once the car stopped, the idle would return to normal (650-700). Replace hose and idle is fine now.

 

...altitude will play havoc with the old school carburated engines..but that doesn't apply to our Crossfires. My guess is you have a vacuum leak somewhere and the higher altitude is just making it worse....

 

I live at 7000 MSL and both stick and automatic Xfires, Mercedes and Chevy run fine. Checking for leaks has been suggested. At lower altitudes you may not notice it because the computer is able to compensate for the difference faster.

At 700 feet on my old carb cars, I have to install different jets and balance the twin carbs precisely but on electronic fuel injection it does not seem to matter. I also have to play with the timing a little on the carb cars. But that may be caused by distibutors that are 40 years old. There is some wear and tear even with rebuilding them. I also have some leaks from the throttle shafts on the older cars. I can tell this when I spray carb cleaner on the carb body and shaft. It changes the idle. Just my experience.