I have a 2004 Scion xB, automatic that I bought new. It has been an outstanding car and I have run full synthetic oil shortly after I got it. The only engine mods have been NGK iridium spark plugs and a Toyota TRD free-flow air-filter,

The xB has been running great up until about 55k. Over time I have noticed the engine has been slowly getting sluggish and the idle has been too low. At stoplights, it seems like the engine is bogged down and wants to stall so I put it in neutral. This is especially noticeable with the A/C on and the engine idle gets so low that it vibrates and rattles the plastic splash shield under the engine. Also, when the engine is cold there is a "gurgling" noise when you accelerate. Once the engine is hot, the noise seems to mostly go away but is still there faintly. However, the box seems to run good at highway speeds. Also, the gas millage still remains good at 30 mpg.

At 65K I did a "tune up" with: NGK v-power spark plugs, new PCV valve, cleaned the battery posts and ground, cleaned and re-oiled the TRD air-filter, cleaned the MAF sensor, and added STP fuel injector cleaner.

I now have 66.5k and the engine still has the same issues... not as bad as before but still sluggish and the idle is still way too low.

Am I missing something?
Could this be a battery or fuel injector issue?
How long does the stock battery last?
Any ideas?

Thanks!
Rally xB

 

Forgot to add...
I have been getting my oil changes at Valvoline instant oil change.
The mechanic there mentioned that I might want to switch to Valvoline Max Life high millage oil soon as it helps with engine seals and compression. Any thought on this?
Thanks!

 

bump...

 

you might have to take it to the dealer too see what they say about it...

 

Maybe its time for a trans flush...

Long shot... Timing out of whack for some reason?

 

Completely random guess based on the gurgling noise, is your coolant level ok? You might also ahve air trapped in the cooling system.

It is a long shot, but if there isn't enough coolant the gurgling could be the water pump cavitating. Low coolant could also confuse the temp sensor and cause performance issues as the computer gets confused. Very low likelihood, but may be worth checking.

Another even less likely but possible source is the torque converter on the transmission, If it is damaged internally, or there is a leaking seal preventing proper pump pressure it could cause sluggish performance, and there is a small chance it could cause enough drag on the engine to drop the idle RPMs too low.

 

your maf could be the problem: you may need to clean it out:

https://www.scionlife.com/forums/sho...d.php?t=171686

 

check the gaps on your plugs.
the battery is only there to get your car started, and run heavy duty accessories like stereo.
buy some injector cleaner
replace the drive belt.
clean the MAF.

 

Sorry it took so long to write back.... thank you very much for your replies.

I found the source of the vibration and noise.

Remember when I changed the coolant temperature sensor a while back?
Well, I had to remove the air filter box in order to get to the sensor.
Apparently, I lost a part when I took it out and did not notice it was missing when I put it back together.

The air filter box is held in place by 3 bolts, which pass though a rubber bushing in the bottom of the plastic box.
Inside of each rubber bushing is a metal spacer that looks like a small piece of pipe about 1" long by 1/2" diameter.
The metal spacer keeps the bolt from crushing the rubber bushing and acts like a stabilizer to prevent too much movement of the air box.
Unfortunately, the air box is bolted to the back of the engine. When the engine is at low RPM's the engine (and air filter box) vibrate a LOT. Because the rubber bushing was missing that small metal piece, it allowed the air-filter box to vibrate a lot and in turn wore a larger hole into the rubber bushing.
Over time the vibration got worse, to the point of making a plastic rattling noise, wearing the tape off the wiring harness between the air-box and battery, and rattling the hell out of the MAS airflow sensor, which may have screwed up the engines ability to idle properly.

THE FIX:
I cut a piece of slightly larger diameter stainless steel tubing to replace the spacer that was missing in the rubber bushing and it seems to have stabilized the air-box better. However, I have noticed that the air-box still vibrates a little when at a stop light.

QUESTION:
Could the vibration have damaged the MAF sensor?
Since this controls the air-fuel mixture, could this be why the car acts sluggish sometimes? However, once it's up to speed, it seems to work OK.

It seems to me that the placement of the air-filter box bolted to the back of the engine a design flaw, as there is way too much vibration from the engine. Is there a better way to mount the air-filter box?

As for the gurgling noise, I checked the gap on the new spark plugs and they were off a bit. I re-gapped them and now the engine only gurgles slightly.

I also ran some STP fuel injector cleaner and it seems to have helped a little.
What's the deal with Sea-Foam? I keep seeing it on various posts, but I am not sure if my xB needs it at only 66k.

I cleaned the MAF prior to the problem, but may need to clean it again.
Also, I need still need to check the coolant for air bubbles, and the condition of the drive belt.

Any ideas or suggestions would be appreciated.

Thanks!

 

the air box always shakes at idle unless you go with an aftermarket intake system then it wouldn't do that any more...

 

Yes, but could it be enough vibration to damage the MAF sensor?
Also, how do you adjust the idle on the xB?
If the idle was a little higher, it wouldn't vibrate as bad.

 

with all 3 bolts holding it down it doesn't vibrate enough to ruin a maf sensor which i haven't really heard that one before...

saddly we cannot adjust the curb idle speed

 

Check the wires to the MAF, what you're describing could possibly the car momentarily running too rich or lean. Check the wires to see if they are worn/grounded, and if possible simply trade MAFs with someone you know and see if it runs better.

 

The air box is bolted down tight, but the rubber bushings still have a lot of slop in them. The air-box still vibrates, but only when stopped at a red light, so I drop it in neutral as it's an auto. Is it possible to get new bushings somewhere?
Also, I checked the wires for the MAF and it looks OK. I don't have a spare MAF to swap with.
Question: if the MAF was bad would it run poorly all the time?
As I said, it seems to run good when at highway speeds.
Thanks!

 

saddly no you can't buy new bushings

but at the junk yard you might be able to get some extra ones

 

UPDATE: I found out that other people are having the same problems with air-box rattles and low idle issues on the xA and xB. Looks like it's a air-box design flaw and that the idle can be adjusted with an allen wrench.
Check it out and let me know what you think...
http://en.allexperts.com/q/Toyota-Re...n-Xb-Rough.htm
"...The idle is easily adjustable with a #2 allen wrench and a 5/16" or mm equivalent wrench. Simply locate the (throttle body) screw near the front driver side of the engine. It's close to the radiator fan. Loosen the nut and tighten the allen screw slightly. Have the engine running so you can hear/see the engine idle as you adjust the screw..."

 

THE SOLUTION:

HOW-TO TIGHTEN THE AIR BOX
OK, so there IS a design flaw in the air-box that makes it rattle when at idle. Others (on different Scion sites) have reported this issue with the 04 to 06 xA and xB. The fix for me (for now) was to remove the air-box bolts one at a time and add an extra large washer (about 1.5") to the bolt, with a thin rubber pad underneath, then re-tighten. Do this for each bolt. This will allow the bolt head to distrubute it's strength across the entire surface of the rubber bushing and part of the plastic of the air-box, which seems to stiffen it up and reduce rattling somewhat.

HOW-TO ADJUST THE IDLE
Maybe it changes over time, or maybe now that xB is worn in, the idle has changed... but despite what you might think, it can be done and it's very easy. Like all good Toyota engines, there is a simple idle screw, near the throttle lever on side of the throttle body. Adjusted the idle screw until the RPM's are better.

Special thanks to Ricko, who's instructions who helped me solve this.
Here is my version of his how-to steps for an automatic xB:

1. As you are facing the car with the hood up, look near the front of your engine close to the radiator fan by the battery.
2. Locate the throttle body and "throttle lever." It looks like a thin metal wire (the throttle cable) connected to a half circle (the throttle lever). When you depress the gas pedal, or move the throttle level by hand, the cable and throttle level move together and the idle increases.
3. In this area, locate the small nut that has a very small "allen wrench" type screw in the center of it. You may see a tiny dot of yellow paint from the factory which shows the original location of the idle screw.
4. Using a 5/16 (or equivalent millimeter) wrench, loosen the nut only slightly (about 2 turns).
5. Start the engine and let it warm up.
6. With a very small #2 size allen wrench, slightly tighten the idle screw about 1/2 to 2 turns.
7. After adjusting, give a quick depress of the gas pedal again to make sure it adjusts properly and seats.
8. With your foot on the brake, put the automatic transmission in drive. Watch the RPM guage and listen for the rough idle to smooth out. Turn on the A/C and double check the idle. If the idle is still too low, put the car in park, and repeat step 6 until fixed. NOTE: The idle will increase on the gauge inside of your speedometer. An idle between 9 and 10 is ideal. Set the idle at the very minimum that takes out the roughness.
9. Tighten the 5/16 bolt to lock the idle screw in place.
10. You just saved a lot of money for a "dealer repair." Celebrate with your favorite beverage!

Source:
http://en.allexperts.com/q/Toyota-Re...n-Xb-Rough.htm

WARNINGS:
* Be very careful not to get your hands near the fan which will come on when the engine is hot.
* Don't let someone depress and release the gas pedal while your hands are near the throttle cable.
* Be careful not to burn yourself on the hot engine.

 

You might want to put this in the sticky section for how-to tips.

 

I have the same problem in my xA 2004. If suddenly it gets downright embarrassing at an intersection, what has happened is that the air tube that directs the air flow onto the air flow sensor has come loose and fallen onto the air filter so it rattles around hitting the sides of the air box. It's an old problem with Toyota air boxes (10 years at least). They need to redesign the locking tabs on both parts.

I also have the only Scion xA that has a truly effective A/C for 90+ temperatures.