Idle Fluctuation due to aftermarket intake?

[Galavoxx]

Installed the Weapon Research intake just last month and now I have this intermittent idle fluctuation. It doesn't happen all the time but the symptoms are always the same. After the car is warm, rpms will rise to 900-1000 rpms and then drop to around 700-650 rpms. This will continue to happen as long as the car sits at idle. I usually notice it when I pull up to a stop light. As I said, this doesn't happen all the time. Was wondering if anybody else has this issue with any of the other intakes or if this is a common problem? From my experience with motorcycle carburation, this symptom usually means that the idle jet is too big. Since this car is injected, I have no idea why it might be doing this. Seems like it happens more when it's humid outside but that could be my imagination. I also have a custom cat-back magnaflow exhaust. This could also be part of the issue. :confused:

[jcove]

Installed the Weapon Research intake just last month and now I have this intermittent idle fluctuation. It doesn't happen all the time but the symptoms are always the same. After the car is warm, rpms will rise to 900-1000 rpms and then drop to around 700-650 rpms. This will continue to happen as long as the car sits at idle. I usually notice it when I pull up to a stop light. As I said, this doesn't happen all the time. Was wondering if anybody else has this issue with any of the other intakes or if this is a common problem? From my experience with motorcycle carburation, this symptom usually means that the idle jet is too big. Since this car is injected, I have no idea why it might be doing this. Seems like it happens more when it's humid outside but that could be my imagination. I also have a custom cat-back magnaflow exhaust. This could also be part of the issue. :confused:

I'm not sure about everyone else, but I see this from time to time. I have a Vibrant Exhaust right now, but it was doing it a little before. doesn't seem to be a problem.

[Nutzoids]

I don't have a tachometer, so I don't know what the RPMs look like... I also have no Engine Mods... Just a Short Shifter Kit... But sometimes when my Yaris is fully warmed and sitting Idle at a red light... The engine starts shaking the car slightly... And it definitely has a rhythm to it! I was starting to think this was a normal thing in small cars, but this post has just made me nervous!

:evil:

[Spades]

my yaris did it when it was stock, still does it after exhaust on it. exhaust didnt change it. something about the engines idle control...i noticed it does it at any time when at a stop when the transmission is in neutral and it is iddling...it normally sits at 800rpm...then it drops to 500rpm and the engine shudders and then it spikes to 1000rpm.

im sure its either normal or a recall that toyota will send out at a later date,lol.

[Kaotic Lazagna]

that has happened to me a couple of times, and my Yaris is bone stock.

[Galavoxx]

Ok. SO it's not something with the Weapon intake. That's good. I thought I might have an intake leak or something. It does make me wonder why this is happening though considering it happens to cars that are stock and that have mufflers and intakes. Maybe poor engine mapping or an overly sensative ECU. Electric power steering maybe?

I'd like to get a little further into this. Anybody else have this problem or who might have a possible explanation? Chris? Chino? eTima? :iono:

[eTiMaGo]

I don't really remember how it was before changing the intake and exhaust, but I think it is normal, especially as we have an electronic throttle, the ECU always does some tricks with it.

Plus, when idling, the ECU also alternates between a rich and a lean fuel mixture, this is to keep the catalyser working at peak efficiency, so it may also have an effect on the idling speed.

[Galavoxx]

I don't really remember how it was before changing the intake and exhaust, but I think it is normal, especially as we have an electronic throttle, the ECU always does some tricks with it.

Plus, when idling, the ECU also alternates between a rich and a lean fuel mixture, this is to keep the catalyser working at peak efficiency, so it may also have an effect on the idling speed.

interesting. Have you had this problem?

[DTM_Yaris]

It happens bone stock to all of us. Notquite sure why. It is in the stock programming.

[eTiMaGo]

interesting. Have you had this problem?

Well I usually have the air conditioning running, so that itself will cause the idle to fluctuate, but when it's off, yes, it will go up and down over time. I really don't think it's anything to worry about.

Next time I drive I'll keep the AC off and double check to see if there is a relation between the AF ratio meter and the RPMs.

[Galavoxx]

After hearing that this is a common problem, I don't think it's anything to worry about in terms of potential mechanical issues. What bothers me is that this is a new car and as such there should be no idle fluctuation once the car is warm. Thanks for the input.

[eTiMaGo]

Sure, but as the saying goes, it's a feature, not a bug :wink:

[TrancosRt]

Sure, but as the saying goes, it's a feature, not a bug :wink:

It sure is! It's to let you know the car is till on :P. I remember the first time I gave a some friends a ride they were quite sure the car was off! :P

My car does the same thing too. Next time I go to the dealership for the oil change (bought the package) I'll ask the tech about it (if I remember).

[mikeukrainetz]

Mine does that as well, idles around 800-1000 then drops and shudders slightly. I cant imagine that is a built in feature for anything... I had the same problem with my previous car.
Funny thing is the Yaris developed this idle fluctuation about 10000km not right off the lot. Does the yaris use the throttle body for idle air control or is it a seperate valve as on other makes/models?

[Galavoxx]

I have no idea...

[eTiMaGo]

Mine does that as well, idles around 800-1000 then drops and shudders slightly. I cant imagine that is a built in feature for anything... I had the same problem with my previous car.
Funny thing is the Yaris developed this idle fluctuation about 10000km not right off the lot. Does the yaris use the throttle body for idle air control or is it a seperate valve as on other makes/models?

As far as I remember from the technical manuals the idle is controlled by the electronic throttle.

[H2XcapePod]

yup...I noticed the same looping a while back and thought it was kinda sweet! Usually you only get that on tuned cars...the aspirations of a bone stock Yaris...:biggrin: :wink:

[foxtrot685]

i have a scion xA and it used to do teh same thing when i first got it. im thinking its common with the 1NZ-FE. give it some time and miles and it should go away... mine did

[muncher]

its the recirc valve ... uses exhaust air to heat up the air going to the intake

[El Jefe]

its the recirc valve ... uses exhaust air to heat up the air going to the intake

ok lemme straighten some things out in the thread, i see alot of mis-informantion here

ok first off the yaris doesnt have a recirc valve, that is a part from the dark days of emissions control.

the problem the original poster is having is the a/c compressor kicking on and off, it seems like the computer is over/under compensating for the load change. i've noticed this on mine

the only way to fix this will be a reflash of the ecu to smooth the change out. toyota has no released this as yet and i highly doubt they will. it may be annoying but it causes no ill effect to the car as long as it's not stalling out or anything like that.

[Tamago]

clean your MAF

problem solved

[Galavoxx]

the problem the original poster is having is the a/c compressor kicking on and off, it seems like the computer is over/under compensating for the load change. i've noticed this on mine

the only way to fix this will be a reflash of the ecu to smooth the change out. toyota has no released this as yet and i highly doubt they will. it may be annoying but it causes no ill effect to the car as long as it's not stalling out or anything like that.

But I live in San Francisco, I've never even used the a/c. I'm just satisfied knowing that this is a problem with more than just my car. I do agree with you though, I doubt Toyota will ever do a recall to fix the problem.

[Galavoxx]

clean your MAF

problem solved

Are you saying it came from the factory with a dirty MAF? I doubt it. I'll take a look though.

[Tamago]

if you've installed an aftermarket intake, the filters come oiled.. oil gets on the MAF and dirt sticks..

it's something to clean when you change your oil

[Galavoxx]

I can see how this would be a issue, though I've never had it happen on any other gauze/oil equipped car I've had. In my case however, I got the Weapon Research Foam non-oiled filter. Plus, this problem has occurred with other cars running a stock airbox.

[El Jefe]

But I live in San Francisco, I've never even used the a/c. I'm just satisfied knowing that this is a problem with more than just my car. I do agree with you though, I doubt Toyota will ever do a recall to fix the problem.

how often do you have your car in either of the defrost settings? that also turns the a/c compressor on even tho the little light does not come on.
try it out and let me know, test it with the a/c on or in defrost mode, and then with everything totally off.

[Tamago]

and any of those times did you check to see if the MAF was dirty?

[jcove]

and any of those times did you check to see if the MAF was dirty?

I don't have an aftermarket intake, and my car has done this from day one. It's not the MAF. I don't think it's the A/C compressor either, as I can't remember when my car didn't do this and I don't use defrost or the A/C 100% of the time. I think someone else stated this is something common to the 1NZ engine. It's not a problem as I have mine serviced at the dealer all the time. I've talked to them about a few things of interest, this included and I was told this was nothing to worry about and it's not a problem.

[Galavoxx]

Good to know.

[skc]

i have exact same problem. glad i'm not the only one.
at idle (when engine is warm) rpm drops to around 500 rpm from 700~1000 rpm.
I'm thinking it might be the header that cause this Idle Fluctuation (not 100% sure) due to change in oxygen content in the exhaust gases.
o2 sensor monitors the amount of oxygen in the engine's exhaust gas and send feedback to ECU if the car is running rich or lean.
i might be wrong but idle fluctuation started after installing MR header & gounding kit.
does anyone else with MR header have this problem?

[FlintS]

It is due to the low idle on these cars. Toyota figured if they lower the idle, then we will save more gas. When a fan engages the idle will spudder and change. Nothing to be worried about. I am sure in about four years we will all have to move up our idle....

[jcove]

It is due to the low idle on these cars. Toyota figured if they lower the idle, then we will save more gas. When a fan engages the idle will spudder and change. Nothing to be worried about. I am sure in about four years we will all have to move up our idle....

That's what one of the techs at the garage told me as well. Finally I remembered what he said. It was just a little while after I got the car so I couldn't remember what he said, just that it wasn't a problem. Thanks, that's been bugging me that I couldn't remember it!

[Slummy]

i just has my 1st service, and mentioned this issue, the tech said everything was "with in spec". idle was around 600.

[FlintS]

If you want it stop then move up your idle to about 750 or so. That way it only drops to 600 when the fan engages. You will lose slight fuel mileage though...

[Captain Slow]

I hate to bring up a super old topic, but I noticed this on the way to work this morning. First time it's ever done this, of course it's also the first time I've driven the car in sub-40 degree temperatures.

hoping it's only because it was so cold outside. it's pretty annoying to have your new car's idle dip and momentarily feel the engine shake and sputter.

if it doesn't stop I'll clean the MAF and report back here. if that still doesn't fix it I'll dig a little further into the problem and see if there is truly a solution other than raising your idle.

[cali yaris]

It's called rev hunting. Mine did that from day 1. It doesn't affect the car at all.

[Captain Slow]

except that it's annoying on a nice new(ish) car.

I took it out for lunch and noticed it doing the same thing, but this time it didn't get really low and vibrate the cabin. must have been the really cold weather this morning.

[Reactor]

I'm pretty sure this problem is caused by the MAF sensor sitting too close to the throttle body on the aftermarket intakes. At idle RPM it does not have the proper airflow through the sensor (it measures less air than it should).

[syntax]

would spraying with carb cleaner the intake of the TB just after the MAF would help?
may need someone to rev it up while spraying it