Anyone know what causes the engine to studder when the A/C is running? It usually happens on my 3rd Gen 4Runner during the hotter months. is this just a tuning issue or more serious? Need some help on this one.... mY boss' 99 4runner just started the same thing...

 

come on people... cant a fellow yota get a little help?

 

I would like to help but have never had the prob..Good luck..

 

I'm currently dealing with the same thing--My a/c has started a little whine to it and oddly enough I've had 2 instances where the engine has studdered and pinged momentarily with a loss of power. There is another thread kinda related to this, and it seems the hot summer seem to bring it on. I'll let you know if I find out anything.

 

Go to Autozone or Advance Auto and see if there are any codes in the computer. Pinging and loss of power is likely a lean fuel issue. Engines that are loaded and running slow develop really hot combustion. You may have some carbon in the cylinders creating hot spots.
Is your fan blade really doing the job? Perhaps the clutch is getting weak?
May want to replace factory fan with flex fan.
If carbon, feed several cans of Seafoam down a vacuum port (power brake hose works good) to remove the carbon.
I would replace the fuel filter if still a problem.
Try a cooler thermostat.
Try a higher grade of fuel in the summer.
If still an issue, replace the 02 sensor.

$0.02

 

Keep in mind guys that this is the hottest summer in history and that can have alot to do with it. My truck doesn't run so well in this heat with the air on high and climbing a mountain. I stutter too!, Lol. Mike

 

Is this at idle or all the time?

On the earlier engines, there was a fast idle air valve that bumped the idle speed up with the A/C running:
http://www.4crawler.com/4x4/CheapTri...ne_Pix/11.html

I think on the later engines, that may all be through the ECU. But check the Factory Service Manual to see if there is any testing procedure for that. On the early engines, you could adjust the fast idle speed and also test the vacuum switching valve and the vacuum lines operating it. It was common for them to get plugged with carbon.

 

Sames thing here!!!

It has to be heat related... it wasnt until these 100+ days started about 2 weeks ago that mine began "almost dying" when the A/C kicked on. It has made me nervous to be honest....

I hope someone can come up with something soon. I agree with the Fast Idle switch idea... I'm pretty sure that when operating in normal weather, mine kicks up the idle when the A/C compressor comes on.

Maybe these Yota's just cant handle this kind of heat AND running the A/C at the same time? It is hard to believe that I've had a 1970 Oldsmobile 98 that worked like a champ through hot-ass summers as well as desert conditions, but this 2000 4Runner cant take it.

If anyone has found an answer, PLEASE post away!

James

 

I can say that mine is idling fine w/ the ac on, I've just developed a slight whine when it's running and I've had two different times that my power just dropped off and a lot of pinging occurred--just figuring it's heat related? We've had multiple 90+ days

 

Seems like this only occurs when it is first started up, but I have noticed that it will creep in every once in a while when driving. it is definitely worse during the summer.