car4nita

I just bought an xB last month. I have just over a 1000 miles on it. I'm experiencing some rough idle when the AC compressor engages. It causes some rough vibration and I can hear some rattling sound much like a loose part knocking behind my dashboard. When the AC is not on the idle is fine and there is no knocking sound even when the air blower is on. I also observed that when the AC compressor engages, the whold air cleaner housing shakes violently. I suspect this is causing the vibration which cause the knocking sound coming from behind the dashboard. Has anyone experienced this and what was the fix?

Also, please advise on the following;

What is the specified engine RPM during idle when the AC is off?
What is the specified engine RPM during idle when the AC is on?

Sincerely, Nitz

ayS

have the dealership look at it under warranty. this is defintely not normal. someone else posted a simliar thread on this somewhere else on this forum. if i find it i'll link you too it.

ayS

found it!

https://www.scionlife.com/forums/viewtopic.php?t=138337

boogi_man

mine does the same thing i found that the fuel line that runs ups the firewall has broken its mounting clip. still haven't gotten by the dealer yet to ave them replace it. the vibration has been there since day one but when the clip snapped it went from vibrating to making a lot of racket.

car4nita

Thanks guys for the inputs. Went to the link and read all of the posts. My air filter housing assembly definitely shakes violently. I believe a normal vibration/shake should be similar to the engine. But the whole assembly shakes very much more than the engine which tells me it's not normal. I have an appointment with the dealer next week and I'll relay all the observations this site has made.

Just a thought. I'm thinking that if I can attached a bracket between the top part of the air intake assembly (using the hose clamp) and the engine block, that migh elliminate the violent shake. What do you guys think?

Thanks again guys.

Nitz

P.S. This is great site. Well done.

vintage42

I don't know the specified rpms. I am used to older small engines having the AC reduce their idle rpm, or the computers on newer engines raising the rpm back to what it was without the AC. So I was suprised to see that my 5-speed xB raises its idle to about 200 rpm higher than normal. Normal idle is 575 rpm. Turning on the AC raises the idle to over 750 rpm.
It sounds like your air cleaner is loose.

WagenMaster

Getting a grounding kit really helps with the rough idle from the compressor. It was almost the first thing I did back in '04, and I got it from GroundFusion.com.
Although, if it's causing something to rattle or shake violently, you may wanna take it to the dealer....that's not normal.

mc1200s

my air filter housing shakes too. It just how it is. I dont think anything is wrong with our cars.

mightyboogaloo

Yeah, I have the same problem too. The dealership told me not to worry about it and that it was normal. They told me that these engines just tend to run a little more rough and a little more noisey than your usual engine.

scionmike05

YEA I HAVE THE SAME ISSUE AS WELL AND THE DEALER CANNOT FIND ANYTHING WRONG I THINK ITS RIDICULOUS IF ANYONE FINDS ANYTHING ELSE LEMME KNOW THANX,MIKE

firesquare

This is all normal for a 4cyl motor. when the AC engages it will rev the motor up a bit to keep the thing running. around 1200 max is what i notice. as for the rattle behind the dash, i think their is a dealer repair on that. but remember were driving econo cars so rattles and squeake will come and go. i just turn my radio up :-P

oh and congrats on the purchase of your scion!!

car4nita

Thanks all for the valuable information. Before I went to my warranty appointment with the dealer I found what’s causing the rattling sound behind my dashboard. Just what boogie-man from Jax, FL said, it was a hose line which got unsnapped and was hitting the firewall. I’m not sure if it was a fuel or vacuum hose. I snapped it back and observed the engine again. Yes, the air cleaner assembly resembles a top heavy upside down coke bottle without support. The hose line was so short that it got unsnapped when the engine shook rearward and the cleaner assembly shook forward because the top of the cleaner was not anchored strong enough to the engine. Sooner or later the mounting neck or base of the air cleaner tower will develop material fatigue and snap, break, crack or tear. The whole assembly should shake in unison with the direction of the engine. Meaning when the engine leans forward the tower should lean forward and vice versa or at least it shouldn’t shake like a lollipop with a rubber stem. What I did was to tie the tower down towards opposing direction thus, limiting the shakes and preventing the tower to shake in opposite direction as the engine. Go to http://i132.photobucket.com/albums/q...ScionShake.jpg to see the photo of my solution. This is a rough fix and I welcome any comment, suggestion or improvement. I have complete faith with Toyota’s effort in providing us with quality product. However, I believe this is a design oversight.

amec2ldo

Hello all. Thanks for all the great info regarding engine vibes at idle. I have a 2004 xA purchased as a repo in 2008. It was my daughter’s until very recently, so I wasn’t aware of the problems. The first thing I found (thanks to this site) was the common problem of the hose not secured in the clamp on the firewall. A few posts indicated it was a fuel line, but it’s actually a vacuum hose running to the vacuum switching valve (VSV) that hangs on the side of the air box. The hose wouldn’t stay in place, so I secured it with two plastic strap ties in an ‘x’ pattern (each one routed behind the firewall clamp in different directions).

Now for the loose air box that plagues our cars. The problem is three worn rubber bushings where the bolts pass through the bottom of the air box. For easy access I completely removed the air box cover by:

1. Disconnecting vacuum hoses on both sides of the VSV.
2. Disconnecting electrical connectors to the VSV and to the MAF. You can also disconnect the wire harness clamp with a pair of needlenose pliers by the pinching plastic clips where the clamp is attached to the air box cover.
3) Disconnect the large vacuum hose attached to the rubber air intake duct. Loosen both clamps and remove the air duct.
4) Pull the intake duct from the bottom of the air box. This is the harder plastic duct running from behind the left headlight. No tools required and no need to remove the duct completely…just work it side to side while forcibly pulling one end from the bottom of the air box.

Unless I left out a step, you can now undo the air box cover clips (for access to the air filter) and remove the cover. I found it easier to remove the cover by leaving the filter in the air box. Now remove the air filter and voilà – three bolts! Now move the air box around and you’ll see how loose it is on the bushings. You can’t tighten the bolts because of the steel sleeves in the bushings. My first inclination was to just remove the sleeves. After reinstalling the bolts I saw a noticeable difference. What I didn’t like was the bolts weren’t that tight without the sleeves installed (no metal to metal contact). Tightening them too much would further destroy the bushings. I made a few attempts to reuse the same bushings and sleeves with washer stacks, etc., but I still wasn’t satisfied. I also learned the bushings aren’t sold separately…you have to buy the WHOLE air box at $260!

I stumbled across the final solution at AutoZone. I took a chance and paid $3.99 for Dorman wiper motor bushings (part number 49450). Unbelievably, they came as a set of three – exactly what you need for the air box. They fit like a glove! To see what I mean, leave one of the old bushings in place and install one of the new ones in a different hole. The old bushing is a very sloppy fit, the new one doesn’t move at all. So I installed all three new bushings. I also used the new steel “hat” sleeves that came with them by installing them from the bottom up. I realize two of the three original steel sleeves aren’t like the new ones, but trust me when I tell you the new ones work well.

Then I reinstalled the air box and tightened the bolts firmly. What a difference! I put everything back together (after cleaning the MAF) and took it for a ride. I will tell you it didn’t take care of all vibes associated with these small engines at idle, but it made a VERY NOTICEABLE DIFFERENCE! Let me know if this helps!

Jan06xB

You guys need to check your plugs and run some injector cleaner through your engine because my engine idles really smoothly and quiet. There is some intake pulsing which is normal. If that bypass air valve is supposed to raise the idle when the ac is running and its not working then that's your problem with the rough idle. My idle is in the low 700 rpm and 645-650 with the ac off and engine warmed up after a few seconds when stopped at a light.

elvisphall

I believe that I have found the solution to our air boxes shaking violently when idling. I completely took out my air box and noticed that the metal arm that the air box sits on was broken. Keep in mind everything is factory on my tC. The arm is so thin and dainty that it just can't hold the weight of the heavy air box. It broke after some 5 years of normal, everyday operation. I will need to get it re-welded sometime. I hope this helps.