BinaryJay

Hi guys,

I decided to make a separate thread from the existing RPM Spike thread as it seems that this might be slightly different. I have an appointment for Wednesday to have it checked out but I want to figure out as much as I can about it before paying them to tell me it's fine. :| In case you haven't read that thread, the gist is that I've noticed my idle after cold start hunts up and down for a while while the engine warms up - at least primarily that's when it hunts, I've noticed a very slight hunting at idle after driving for some time as well on occasion but for the most part my idle is pretty good after everything is up to operating temperature.

So, first, I'm a bit lost -- the engine has two air hoses, one on the passenger side which is larger and the one on the drivers side which is smaller. Does anybody know what each of these do?

Second, I noticed that where the drivers side hose meets the engine block, it seems to be wrapped up many times by a black fabric tape. It seems peculiar to me, and I wish I had looked at it before I had my spark plugs changed by Toyota to see if it appeared after that was done. Shouldn't these hoses be completely secured by a standard pressure ring? I am wondering if a tech cracked/broke the tubing when removing this at some point and rather than replacing the part they wrapped it up in tape and said that's good enough. If anybody could check this on their engine, it would be appreciated.

My third observation after starting the car and putting my ear to the engine was that on the drivers side I can distinctly detect two sources of hissing noises. The first point, unless it's just echos and my ears playing tricks on me is where the two tubes meet with the top of the coolant tank. The second point, is, you guessed it, where that large ribbed hose meets the engine block which is currently wrapped in black fabric tape.

So, I am going to hazard a guess that I shouldn't be hearing any hissing/sucking noises. It almost sounds like my last car after I put a CAI on it, that sound of sucking air. With the factory airbox, I shouldn't hear that should I? And if I were to hear it, would I be hearing it in that location?

Since I bought the car from Toyota directly off of lease, and I haven't serviced the car anywhere other than that Toyota dealership myself -- any kind of botched repair job would surely be Toyota/Lexus' doing. I can't see the previous owner going to an independent for any problems since it's under warranty.

Any insights appreciated.

Update:
One Lexus SA emailed me back about this and said:

:| Could be normal???

My original video:
http://www.youtube.com/watch?v=IJIopRXnOzo

BinaryJay

34 views and no thoughts? :|

I have to take the engine covers off... now I'm thinking duh, on the drivers side that is not an air hose, it's a wiring loom and it probably just leads to the fuse box. So I don't know what could be causing the hiss sound from there. I put my ears right up to the coolant cap and I hear some spurts and hisses seeming to come from there every once in a while, but I can't figure out how that would affect the idle, especially considering that one of the tube ends that leads down just leads to knowhere (just to dump overflowing coolant).

So I'm at a loss.

passnu2

iTrader: (33)

Im going to guess your just hearing the pressure release from the coolant overflow since its right there.

I have the V8 so a little different....I had the same engine in my IS350 and never had that issue. Things I would suggest to try while you have the covers off.

1. Check the MAF sensor (may be dirty)
2. Check the Air Filter just to make sure something wasnt sucked in or its just dirty
3. Clean the Throttle Body

Try these and check back. I wouldnt go to the dealer just yet until you try a few DIY checks that may provide the answer and or fix whats going on. Maybe someone else will have some suggestions or ideas outside of mine.

BinaryJay

Thanks for the reply.

1. Does the MAF even affect cold idle? Maybe I misunderstand but I thought that there was a separate valve that controls the intake during cold starting controlled by coolant temp only. When I think MAF, I think of throttle response. I do have some electronics cleaner that I used to clean the MAF on my previous car when I installed an SRI so I could always do that. Not sure if it's held on by torx screws, if they are I don't think I have any torx heads.

2. I plan on taking a look at the air filter even though it's thousands of km away from "requiring" to be changed per service schedule. I'm not sure how a clogged air filter would cause this strange cold idle behavior and then go away after a couple of minutes though.

3. I'll take a look inside the TB. I thought I read that you can't move the butterfly valve on these cars by hand though so it might be kind of difficult to clean. Now, if it is really gummed up I'd have to wonder how on earth it got that way in the first place.

My feeling is that its either a vacuum leak that I can't detect, or maybe there is air in my coolant that needs to get bled out though I don't think there is any way to diagnose that short of having the fluid flushed and seeing what happens after that.

passnu2

iTrader: (33)

Your welcome!

My MAF was held in place with 2 phillips head screws, I would assume yours is the same. Easy to take out. use a Q tip or something similar to gently clean with the solution on the Q Tip. I did this a few months back, didnt notice any difference on my car, but it looked like it was clean before I did this.

TB I took a clean rag and pushed it open. I didnt remove mine but I guess you could. My car has ~44k miles on it or so and it looked like it was the first time it had been cleaned. I did these because I thought my car idled very low but I guess its just how our cars are.

all three of these could be a part of it. A vacuum hose could have come loose also and doesnt hurt to check them while you have the hood up. I really dont see what more you can check yourself. If these dont show any signs of improvement I would have the dealer or a Tech look at it from there.

anaq110

Guys,

I'm having a similar issue and took my car over to NorthWest Brampton. Service Rep told me this is normal but he will report it into Lexus corp.

My exact problem is when the car is outside in the cold 30 degrees and lower, I notice it rpm sit about 1500 and have to wait about a couple minutes for the rpms to start settling to approx 1000. Then about 5-8 minutes for it to be normal 500-700. Another thing I also found odd was I have to press my brakes really hard at a red light, the second I give the slightest release off th e brake pedal and the car jumps...

I will try to make a video tomorrow and post it up here. My cousin who runs a garage in Jersey mentioned all symptoms sound like a vacuum leak so I think you might right on your findings.

BinaryJay

Well, I couldn't sleep so I decided to go down and mess around with the car.

1) My air filter was white, like brand new. I hate how the top of the airbox is connected to the intake duct. I just peered underneath it, air filter box had a bunch of oil sitting in it from when I last had the car rust proofed. Dirty, but insides were clean except for the usual fine sand and crap sitting at the bottom of the airbox. No vacuum with me so I left it as it was and clipped it back shut.

2) The intake air duct coupling at the air box was not tightened very well. It was also not sitting flush with the marking "stopper", kind of askew. I loosened it, reseated it, and then tightened it as tight as I was comfortable squeezing it.

3) The MAF module also moved around a bit when I put pressure on it from side to side. I unscrewed it (one of the screws is corroding... other was fine, weird), it still took a bit of a pull and jiggle to get it out so I don't think any air was getting in there even though it seemed a bit loose. I sprayed the wires and the little bulb down a few times from a bit of a distance gently with automotive electrical contact cleaner, same stuff I used on my past car so I knew it wouldn't destroy it. I let it evaporate a few minutes outside of the air duct while I wiped down a few things. It was a bit dim in the garage and I forgot to bring a flashlight so I'm not totally sure if I actually cleaned anything off it or not. Reinstalled, tightened as much as I thought I could without risking stripping the screws especially the corroding one.

In my haste, I only cleaned the "bulb" part of the sensor, and I totally forgot to actually spray inside where the other wires on. At this point, I guess I will leave well enough alone unless something crops up again though. Not sure if it's worth going the distance and taking it back out again.

I gave it a few more minutes while I got my engine covers back in order. Started the car. The car has been sitting for a good 6 hours or more since the last time I was messing around with it, and I never took it for a drive today so I have to assume it was as cold as it could be.

With some trepidation, as always whenever I mess with a MAF, I started the car. Sorry didn't think to make another video. The idle went up to around 1500 immediately, then after a few seconds dropped down to 1200 or so. I thought okay this is when it will start hunting and I waited. No hunting. It stayed at 1200 for some time, after I was satisfied with what the tach was showing me I went and listened to the engine around where I worked and didn't hear anything unusual. I let it run for a good 10 minutes at idle and I didn't hear any surging.

After it made it's way down to a steady 1000, which it seems on this car it stays at for quite some time if you're not driving it, I gave the accelerator some push and everything reacted nice and normally. I revved it all the way near the redline in neutral, still no hiccups. Let off the gas, it returned gracefully back down to idle. Let it idle a bit longer, and satisfied and tired decided good enough for today and here I am.

So, it could have been either the tightening of the air duct and/or tightening of the MAF module or it could have been the MAF cleaning but something seems to have made the car behave again. I will see how it goes tomorrow afternoon after it's been sitting all night but I have high hopes that it's good for now.

It was too late and I was too tired to bother taking off the entire ducting to look at the TB plate but I guess it's fine for the time being.

Anaq110: It sounds like yours is completely normal, it's supposed to idle high until the coolant warms up. The colder the coolant is the longer it will high idle. Every modern fuel injected car does this. Or did you mean that your RPMs hunt up and down like mine was doing?

Car jumps when idling high because it's the same as if you had your foot on the gas after it's been warmed up. I don't know about the hard braking, for that, yes, you may have some kind of vacuum leak since the brake boosters use the engine vacuum.

I found myself badly wanting even a simple code reader to see if the car could tell me anything that wasn't quite setting off the dumbo light. So I searched around and found this little gadget...

http://www.actron.com/product_detail.php?pid=16350

For $50, not too shabby, looks fairly high quality. Small enough to keep in the car all the time and doesn't need a battery. Has a little indicator that quickly lets you know the severity of the codes thrown. Simple enough that I can show my fiancee how to use it in case something happens when she's got the car so I can decide what to do right away, especially if I'm at home and can google the code (or go on the actron site) to look it up.

Saw a few cheaper options, notably no-name brand chinese readers with no display requiring a laptop to be involved, figured this was better for what I'd use it for.

passnu2

iTrader: (33)

Glad it all worked out for you.

dubzino

We have been getting some cold weather down here now 1-2 degrees celcius. And I notice my car does this also. When I put it in drive the rpm are at around 1000 instead of 500.Until I drive it for about ten minutes it will go back down to normal. Is this normal? I figured it was just because the car wasn't warm yet. Can anyone confirm this?

dubzino

confirmed its normal. Thanks for the help

chuckGS350

Confirmed. A cold night in Mass. My car behaved the same way.
That's why I let the car warm up a few minutes before driving away.

Simmsled

Warms up the cats. Emissions thing it is...

Boron

Better to drive gently (2-2.5K RPM max) as soon as you've started the engine rather than sit idle for a while.
Bad enough having to do it in rush hour traffic, but not necessary on your driveway.

Simmsled

Truth.

morganc

Good to know.