AC Pump and Idle

M

MacVay

New member
I have noticed that when the AC pump kicks in on my 05 V8 Limited, it pushes the RPM's up about 250-300 RPMS. When this happens if you are stopped and light on the brake the truck will inch forward.

I have also can feel the pump kicking in and out while driving on the highway. You can feel a little Accel when it kicks in and then a decel when it kicks out.

Is this normal? Anyone else with the same issue?

Cheers,
 
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I have the exact same probblem. I just came from the Toyota dealer and they say that is normal and it is electronically controlled by the computer. I went to http://techinfo.toyota.com/ and did find a mention of a A/C Idle-up adjustment screw but nothing else. I also found that if the idle is more than 100 rpm out the computer will adjust it automatically. We may be SOL!
 
The ECU raises the motor speed when the
A/C pump is engaged so that if you stop
at a stop street the motor will not stall.

Cliff s
 
I completely understand why the Idle may have to be compensated but I think it is being compensated way to much.

It is really annoying when you are stopped because if you don't put enough force on the brake pedal, when the AC Pump kicks in the truck inches forward.

It appears that this is only an issue with the 05 V8's. Do all of you with this same issue have 05 V8's?

How is your idle quality? Mine is poor with kicks and bumps felt through the steering wheel and seat. I thought they were related to the AC pump because when it kicks in it gets worse.

I bet you will see a TSB in the near future about the AC Idle Compensation.

It is real funny, when I am in my driveway (Incline) and I have the truck in drive, it will sit where it is. If I turn on the AC or put it to auto, the Truck will crawl up the driveway. Turn it off and it stops where it is. Kind of like a crawling cruise control.
 
Since i had the truck, i haven't used the AC, so i am interested in find out if it happens to mine.

On side not, (and sorry for kinda hijacking the thread), anyone know the amt. of HP that the car looses when the AC is on?


Just wondering
 
Don't count on a TSB... This is probably due to the voltage sensor on the output of the alternator. Once it goes below a certain threshold, the engine computer will raise the RPM's to increase alternator output and bring the voltage above the threshold point.
 
chunderboy said:
Since i had the truck, i haven't used the AC,
Click to expand...

You should really run the A/C and compressor at least once a month to keep the internal seals lubricated and the unit functioning properly.

I only run the A/C during the hot summer, otherwise my windows are usually down, but even in the winter, I will manually activate the compressor in defrost mode to keep it all happy.
 
Sac State said:
You should really run the A/C and compressor at least once a month to keep the internal seals lubricated and the unit functioning properly.

Click to expand...

That is almost unavoidable with the quirky auto climate control. :bash:
 
Good point. I will do that tonight. But i am the same way. Gotta love the windows down, with the rear window and that huge efing sunroof.

All about fresh air.
 
My 04 V8 does it too.

It is a little more pronounced in the 4R, but every car I've owned, back to a 1976 Trans Am, has had this issue when the A/C is on.

The only thing I can think may cause it to be more noticable on the 4R, is that the torque converter may have a lower stall than most other vehicles. I say this because I can feel the 4R surging against the brakes even when the A/C is off. My Expedition does it too, just to a lesser extent.

--Mike
 
Low 1st gear (V8) + mega-torque = serious power off the line.

I'm always babying the gas pedal at stoplights. If I give it normal gas, it looks like I'm racing.
 
I've noticed this as well on my 05 v8, now that I've started to use the AC a few times. I have an appointment at the dealer tomorrow anyway, so I will have them check it.

I can understand that the RPM goes up a few hundred with the AC on. But I've noticed that standing on the brake at a light, the RPM goes up and down every 20 seconds or so between 500 to 750rpm and back. I would think the rpm would go up with the AC on and remain constant, not fluctate back and forth. And if you aren't paying attention and holding the brake tight, the v8 takes off (I think Toyota calls this engine creep).

Anyway, worse that this is the very odd feeling at highway speed, where you can still feel this change in rpm as you are moving. Almost feels like you are hit with a strong gust of wind, like a slight hesitation. I hate this.

I've only noticed this with AC on, or defrosters.

Steve
 
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mine does it too. the rpm increase doesn't bother me, but the little jump forward does. i usually don't step on the breaks too hard so it's kinda annoying when the car does a little leap to go. i just tell myself that it's the V-8 wanting to show-off. hehe.
 
Mine does it too. All my vehicle's have done that to some extent , but I do notice it more with the 4R.
 
As expected, and as others have mentioned, Saturday had my 4R checked at the dealer and they told me this is absolutely normal.

Steve :confused:
 
05ToyRunner said:
As expected, and as others have mentioned, Saturday had my 4R checked at the dealer and they told me this is absolutely normal.

Steve :confused:
Click to expand...
If normal means they all do it, there's no fix, and it doesn't hurt anything.....it's normal. Because this seems to be the case with all of them I've driven (dozens).

Although I've never had it creep forward at a light....but I probably just hold the pedal down enough that doesn't happen I'm assuming. It could be more noticeable in the 4R than other vehicles because it has a lot of power available right off idle.
 
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