This morning I started my TL for the first time since sept. and the engine is reving up and down repeatedly. Has anyone experienced a problem like this? My TL is 1999 and 74K mi. Thanks.

 

drive it around, put in some fresh gas, open her up a bit. may be just a little "clogged" up in there.

 

That's not a gas problem, that's Idle Air Control valve most likely.

 

check all intake and vacuum lines to make sure they are connected and plugs also. it sounds like your tranny is going though.

 

IAC valve has nothing to do with the transmission. No offense, but you guys should really research this stuff before giving your opinions. A car idling in park will not give you any insight into a transmission. I've had the same problem with an Accord that he is having with his TL, and it will rev between like 1000rpm and 2500-2700rpm and fall off, over and over. It was the IAC valve.

 

Did you fill you car with regular gas? My wife filled up my car with regular gas, then my tl engine started to rev up and down when it is neutral gear. It's between 1000-2000 rpm. It happened before I used up that tank of gas. I filled up with 93 gas. After a couple short run, the problem gone; however, the engine light is on now. I don't how to turn it off. Is anyone know how to turn it off?

 

Again, please leave the diagnosing to people that know what they're talking about.

It is the idle air control valve. It's attached to the throttle body and periodically gets clogged.

Part #2 Lower right of picture


You might want to try cleaning it out first. Where are you located? If you're not comfortable doing it, maybe someone can give you a hand.

 

Disconnect the negative battery terminal for about 5 minutes. It should stay out. If not, have someone use and ODBII tester to pull the code.

 

87 octane gas will have no negative effects on the TL except for perhaps subtracting a few HP. It will not cause engine idle speed problems or CELs.

 

my bad I guess I was tired and didn't read his post closely enough. of course it's not a tranny issue if he is idling. IAC valve makes sense.

 

Same thing appened to me when i changed my TB for a TypeS one .. the IAC valve was defective.. ive just swapped the one from my tlp on the typeS tb.. owever i got a CEL at the same time .. ive checked it and it was something with the tranny .. so i jumped on the occasion and changed my 4speed tranny at 160kmiles :P

 

Thanks for help guys. Is it easy to get to the idle air control valve? Do I need special tools to get it out? How do I clean this? Soak in the gas and blow with air? Thanks again.

 

Yesterday I took my car for a drive to see if running the engine under various driving conditions would clear problems in the Idle Control Valve. During driving, I could feel the engine is trying to rev up and down as it was in idle. I stopped and turned ignition off and waited a few minutes and started the engine again and the problem went away! Today I drove my car to work (40mile drive) and no problem so far! I guess for TL, it is important to drive in regular basis since this problem occured after the engine did not run on for a while.

 

Clean it up because someday it wouldnt work ...

 

How do you clean it and with what? Do you have to remove it ?
Thanks

 

couldn't have said it any better, if u dont know dont post wrong or misleeding information

 

are there just 4 bolts that holds on the throttle body? is there anything else I need to take off before I can rotate the throttle body around so I can get to the IACV, like the throttle cables or can I just leave them on. and if I have to take the throttle cable off, how do you do that? I'm gonna change this IACV myself, thanks for the info.

 

I would disconect every thing that attaches to the TB just so that there is no chance that you accidentally break or pinch something. If you manually open the throttle on the back side of the wheels that the cables ride on you will see there is a slit in it. You will lift the cable slightly and slide it out the side.

 

It was a cold night last, I am having the same issue, my 99 3.2TL is revving on idle up to 2500 and then dropping, and revving again, etc. It was also idling much higher than normal. After I let the car warm up and turned it on an off a few times it went away. But I'm sure it will be back - so I'd like to try cleaning my IAC valve. My question is, when I take of my TB and then IAC valve am I going to need new gaskets or are they resuable, and if not can I use that sensor-safe blue RTV liquid gasket stuff?

I've used it before and it worked a cooling system part, what are your guys general opinions on the liquid gaskets?

Thanks

 

I needed to fix this for the next day so so took off the TB and removed the IACV to clean it. It was caked all inside with sooty carbon. I sprayed it with carb cleaner, and let it soak for a good 10 minutes the hit it with a toothbrush. I didn't want to get the carb cleaner in the sensors on the TB, so I didn't directly spray it. I wiped out the TB itself, there was some carbon buildup on the throttle valve and immediately surrounding it. Then I dried and blew them out, and slapped the IACV back onto the TB and reinstalled it.

The removal procedure was like this: (1) pop off the throttle and cruise control linkages (2) disconnect three sensor harnesses (3) removed two hoses from the big intake hose that connects to the air filter. (4) unscrew the tension ring from the big hose (5) pop big intake off the TB, and pull to one side. (6) remove all hose from the TB, including the ones that feed it engine coolant (I suppose to de-ice) (7) unscrew two nuts on top and two bolts on bottom (8) yank off the TB, and remove part way, throttle linkage bracket is still attached (9) unscrew throttle linkage bracket, and remove TB completely (10) clean TB and IACV (11) reverse procedure to get it all back on. I used the original gasket that was still is good shape and just added a bit of liquid gasket to make sure it sealed.


Since it was cold out, the rubber was stiff and hard to work with. So I borrowed a hair dryer and warmed them to make them more pliable. Made the air intake from the filter much easier to pop off and on.


BTW I took pictures, I could post a more detailed howto if anyone is interested.

 

That would be great, I will attempt this as I bring my '99 back to life.

 

did u remove the iac from the throttle body or u cleaned it still attach to it

 

I did, otherwise you cant get to the valve really..its held on by two machine screws..those things were actually the hardest thing to get moving, I used some wd-40 to help loosen them, and make sure you use exactly the right size phillips screwdriver to avoid stripping the head. I used a pair of vice grips on the handle of the screwdriver to give me more leverage. I did want to remove the plastic housing on the IACV to see what was in there but alas it has a bigger torx head than I have a screwdriver for.

I've driven 40 miles so far with it and the problem has not repeated yet. Even this morning when it was coldest (34 degrees) it started up fine. If it does come back than an ex auto mechanic buddy of mine said it was probably just failed and a new one was in order. They cost about $100. At least now I know I'd only have to pay that and not some ridiculous labor charges.

 

Here are some pictures to go along with my description of the process. I'd take more but I don't have my camera anymore.

First shot is of the throttle body in the car from overhead/front. The IACV is on the bottom facing down and theoretically you could remove it with the TB in place but practically it doesn't seem possible.



Here's from the side. Note the throttle linkages for the accelerator pedal and the cruise control. Removing these is simple, just rotate to the fully open position and the throttle cables slide out to the side. They have little cylinderical terminators like what you might find on bicycle brakes. You'll have to remove that throttle cable bracket too to get the TB out.



Moonshot of the TB. Enough freakin tubes? My next car is going to be simpler than this, I hope.



Where did it go? Just remove all the cable harnesses and the tubes going into the air intake near the TB. Then remove all the TB tubes. Then the IACV tubes. Then pop off the intake. Then unscrew the TB, yank it off.



Here is the TB out of the car. Note the valve that controls air inflow to the engine, which is coupled to the throttle linkages. Here the IACV has been removed already, but it WAS attached to the right side of the TB in the picture.



Another shot of the TB where it attaches to the IACV. See the three compartments? Two lead to either side of that throttle valve, so it can be bypassed when the engine is idling. Otherwise, when you let your foot of the pedal the engine would suffocate and die . The third port is for engine coolant to flow through. A very simple heat exchanger, which looks like it is switched by a hydraulic solenoid in the engine compartment. I think this is to provide heat to the TB and IACV when its cold. Like carb heat on a Cessna 172. But this must be automatic, since I havn't located the carb heat button in the car.



Last but no least the IACV valve itself, and the little rubber grommety doohicky that seals it. Its soaking in carb cleaner and got a toothbrushing later.



Hope this helps someone.

 

Great pics and advice. Was much easier in my Honda Accord 91. Had the same problem with it after 302000 miles.

 

Hey Gizmobuilder,
could you please post those pics again. I want to clean my IACV but I am a bit nervous. I asked acura how much to replace it. They told me $285+tax. If I could spend an afternoon and do it myself, it will save me $300.
How long does it actually take to clean?
Thanks
A

 

pics????

 

Pics aren't working

 

Its Part # 2 in the pic here.

 

what is part number 11 in this picture? Can 11 and 2 cause engine stutter and false sensor readings?

 

Just thought I would throw this out there: I replaced my IAC valve this past weekend. On Friday I was browsing through Harbor Freight and spotted this right angle racheting screw driver. Priced $5 on sale for $3.



It saved me tons of time changing the IAC valve because I was able to unscrew the valve screws without removing the throttle body. All I took off was the big plastic shroud from the top of the engine and the battery shroud.

The gasket goes into a groove on the bottom of the throttle body so I dabbed a little grease on the left and right edges of the gasket to hold it in place until the valve was against it.

The little screw driver is worth ten times what I paid for it.

 

I CANT SEE THE PIX AND IM HAVING THE SAME PROBLEM> CAN ANYONE HELP with PIX? ive been reading forms all day today for 5 hours trying to see what exactly i have to remove and clean. anyone with pictures please please upload

 

DUDE CAN U pleaaaase reupload the pix,, im dying here trying to find any info on how to take care of this problem, i read so many forums and noluck in seeing what people are talking about.. ssmarroush@hotmail.com

1999 TL engine reving up and down problem. i was on vacation car was fine, now car is CRAZY

 

I had this happen to me a couple of times. It's water in the gas. The computer senses a low burn temp and then trys to add more fuel and over revs and repeats.

You mentioned that you had stored it for awhile. Fill it up with fresh gas (high test if you're rich) and it will go away.

ET