Hey all, I was browsing around this forum because our TL is having a bit of a revving problem. From what I've read and researched, it seems that it might be an IAC valve that needs to be cleaned or replaced. The only thing is, there is no CEL that turns on. I know that it could either be the IAC valve or the 02 sensor. Possibly something wrong with the Throttle Body itself but I doubt it.

Stats of the car:
1) 3.2 TL
2) 134,000 miles
3) Automatic

I also know that the spark plugs need to be replaced but from what I've read, replacing that won't do anything because it has to do with the air that's going into the engine, correct? Thanks for the help!

 

Oh also forgot to mention, it revvs while in park and at idle. It goes from low to high and runs a bit rough.

 

what rpm is low to high? 800 to 1200 revs and drops is often dirty IACV- easy to clean
only needs new gaskets
Clean TB throat-air plate while its off the car to clean IACV

Lube throttle return springs, good idea to lube throttle cables too

miss can be dirty parts, old plugs, bad coil, loose ignition wire after plugs replaced etc.

 

CEL only comes on for some of those issues,,dont wait or depend on it

 

in Drive gear, what does it do- driving and when stopped at a light?

 

the IAC will only effect idle conditions and will have no effects on off idle conditions FYI.

I would get a fuel pressure gauge and hook it to the fuel rail and verify the fuel pressure. While at idle there is no load and very little gas is needed to increase RPM, while under load that is not the case and more fuel is needed. Check the fuel pressure regulator and the vaccum line going to it, make sure the line isn't weather checked or cracked and that it is connected properly.

If you car get the car up to speed with light pedal pressure and then you have the issue when more pedal pressure is apply that is a classic fuel pressure symptom, so it could be a fuel pump or regulator problem.

air isn't going to be the issue unless the air filter is clogged and that is easy to check by putting a light behind the filter and looking through it and you'll see how dirty it actually is and it would have to be almost completely blocked to effect the engine.

 

It's the idle air control valve.....Try cleaning it before replacing it. Costs $500 at the stealership..

 

2 gaskets and some carb cleaner to fix the crud buildup thats the source of prob

or replace entire unit like dealer wants too!!!
hmmm how much are those 2 gaskets?

 

Our TL is acting exactly the same way (wife just pulled into the driveway completely freaked out, saying it was "driving itself!" translated = also revving while in park). Did you figure out how to fix it? Could anyone point me toward directions on how to clean the IACV/TB throat-air plate? Or is that irrelevant if idling while in Drive, as rcb2000 said?

Thanks to all for your posts--this is a terrific forum.

 

I think he only said above idle- not idle in drive
This is a common problem on the TL , just like EGR port clogging

DIY clean the IACv..there are threads on it here
4 bolts on the TB, some minor things to remove along the way
get new gaskets ahead of time `just in case`- better safe than stuck if 1 tears!!
tell the parts guy what you are doing

 

or DIY the egr ports and TB cleaning together, 2 hours 3 cans carb cleaner- non chlorine

easy to remove entire manifold and TB -then access the lower TB bolt, than in the car

 

Check also your cruise control cable linkage at the throttle body. The little plastic semi circular pully kind of thing where the throttle cable and the CC cable is attached breaks and the CC cable gets in the way of the throttle cable so it doesnt retracts properly. It causes the rpm to stay high ( around 2K - 3K) when you stop at light. If its that and u dont want cruise control, u can just fold the cable back and attach it with a tie wrap.

 

Thanks to all for your input.