RPM @ Idle

Is it normal for the idle to go from 600 to 900 and waver back and forth? Almost like when the AC compressor kicks on.

 

Nope, mine is steady as a rock

 

Engine up to temp?
Was the defrost on?
If it's oscillating like that constantly, that's not normal.
If the engine is not up to temp and you apply the brakes (clutch in), the rpms will rise from idle and hold until you take your foot off the brake pedal. This is on OR and PRO with fancy electric/hydraulic brake booster. Pretty much goes away when up to temp.
Also you'll get a lil spike when you begin to turn the steering wheel.
Just throwing experiences out there..

 

Might be normal if a cold engine. Idle on my 3.5 v6 will pluse from 800 to 1200 when cold and outside temps are around 50 degrees F. Once the engine temp gauge gets up to norm, its a rock solid steady 800 rpm...at least till the ac is turned on.

 

Normal. It’s just the engine compensating for when the A/C compressor engages.

 

But this with the AC off. I know it increases with it on.

 

Any input on the steering wheel? I believe there's a pressure sensor on the power steering that bumps up the idle as well.

 

Any load that gets added will increase the RPM's. Power steering when turning the wheel, AC compressor when AC is turned on, engine fan turning on, etc. As things turn on and off, you'll see it move around. I wouldn't consider it an issue to be honest.

 

Ok....quick question.....

Can you hear the engine change speed or just looking at the tachometer?

If your tachometer is fluctuating without the engine changing speed, then you have an instrument problem.
If the engine is actually fluctuating, then the problem is much deeper and may need a dealer to solve. Assuming there are no input changes, such as AC on, turning steering wheel....etc.

 

The defroster will cycle the AC compressor too.

 

I hear the engine. Gauge seems ok.

 

Its likely normal if the outside temps are around 50 f or so. It should all stop once the engine is up to normal operating temperature. This provided the ac/heater fan is off.

 

Tatie your foot off the pedal ...lol

 

If you want to deal with this at home, you could try pulling off both of the battery terminals (negative off first and on last) and touch them together for a few seconds. That will do a decent system reset. You'll have to redo some minor settings in the radio.

If that doesn't work, you can do a Learned Value Reset with TechStream and a 5min idle. That will give your ECU a clean slate to learn from. You'll need a good USB OBD adapter for that, like a Tactrix, or a helpful person in your area.

The other potential, besides a loose connector or hungry rodents, is a dirty AMM. There are cleaners that you can get at autoparts store. Read the instructions carefully as not following them can destroy an expensive sensor.


If you're not up for all that, then dealer? 50:50 on them saying that it is normal, though I can assure you that it is not.

 

I'm gonna observe this situation and make sure that I've got all the bases covered, e.g., normal temp, fan off, etc.