HELP - Idle Air Control Valve!

[Colton5419]

Just had my IACV replaced at midas today for about $300 due to having a service engine soon light come on; only to drive back because of these symptoms:

After the repair I am experiencing rpm fluctuations when coasting, basically if I'm at 30mph or even 40mph and lay off the gas pedal the tachometer will jump from about 1500 to 800 rpm and will sometimes make the jump more than 8 times. (doesn't happen everytime and can occur at other scenarios)

This can actually be felt as if the cars accelerator is adjusting to maintain the current speed. The mechanics could not find anything wrong and we agreed to look further into the problem on my next visit, if the problem persists I will be complaining yet again when I go in to have my brakes serviced on saturday.

Does anyone have any ideas on what the hell happened? I have NEVER had this problem before.

[Isaurio]

You have to disconnect the battery for 10 minutes or so. The ECU needs to relearn the new settings from the IAC. Try that first and see what happens. let it idle for 10 more minutes after you plug in the battery back.

[Colton5419]

I disconnected the negative terminal on my battery for over 20 minutes, I know it cleared almost everything as my radio lost all of it's settings etc.

Still having the increase in RPM's when I let the car coast on occasion, usually seem's to be from 1000RPM to 1500RPM and also I'm noticing RPM increase when turning the steering wheel; this nearly caused me to hit my house when backing into my driveway (was NOT expected a rapid acceleration and didn't have my foot on the brake)

Any other ideas? - I thought it needed to relearn as well, but it seems like it should have learned by now

(The needle will go up and down from the 1000RPM to 1500RPM and can be physically felt while driving)

[4g63lover]

It is possible that the problem in the first place was the circuit and not the valve itself so check that out.

If the new IAC was aftermarket it could probably be faulty as well. Seen it happen on a 1G when we replaced the IAC with an autozone IAC.

As far as the idle jumping when you turn the wheel. It is normal and you probably just never noticed it. The RPM will jump when you turn the wheel due to the power steering pump engaging. When you turn the wheel the pump cycles the fluid through the engines natural rotation in which causes the RPM's to slightly jump or sometimes it will even slightly dive.

If the circuit checks out, try an OEM IAC and see what happens.

[Colton5419]

The car is at MIDAS until they fix it, brought it back because it was accelerating on it's own over 20mph including shifting gears. Had to fight it with the brakes and almost crashed a few times

[Isaurio]

Did you try to ajust the idle screw around the TB try to lower it down.

[Colton5419]

I didn't want to move the idle adjustment because it didn't constantly idle too high, it actually would go as low as only around 600-700rpm's even while in drive.

It was almost as if the car was randomly deciding to increase the throttle, or move it.

I had to kick the car into neutral and then people thought I was revving up at them

[4g63lover]

Midas probably messed with the Biss screw on their own.

[jajoyce]

I have the exact same problem! I had my IAC replaced Sept 1st and 2nd along with a Mass Airflow Sensor. The shop told me it would idol very rough for about 350 miles until the comupter readujusted itself because they had to reset the computer. I am at about 220 miles and it is still doing that. 350 miles sounded like a long time, but I will wait and see then call the shop. Let me know if you here anything back from Midas and vice versa. My shop actually had contacted the Dealer to figure out everything with the computer and MAF sensor.

I am also experiencing the acceleration problems. The probelm seem to go away when I reach speeds of 35-40 mph. It is such a weird feeling, but I cannot afford to have my car in the shop for a long time because I need it for work & school. I have never experienced any other major mechanical problems with this vehicle and keep the maintance up to date.

2003 Galant ES 4cyl - 79,500 miles.

[mrg7243]

The car is at MIDAS until they fix it, brought it back because it was accelerating on it's own over 20mph including shifting gears. Had to fight it with the brakes and almost crashed a few times

Hey its a toyota now lmao

[Colton5419]

MIDAS contacted me again this morning, the best "guess" they can come up with is the part they installed must be defective.

Now this is JUST A GUESS; they contacted the part manufacturer and they are shipping a new one over night. Tomorrow (Tuesday EST) I will see if the problem is resolved by simply replacing the part with another.

Also: Yeah, on the phone they said the test drove the vehicle and it was accelerating by itself to speeds of up to 30 -35 MPH.

Now it's just me, but if my car is going to be revving hard enough at all times to reach speeds of over 30MPH, then it is going to SUCK GAS LIKE A BEAST!

[jajoyce]

MIDAS contacted me again this morning, the best "guess" they can come up with is the part they installed must be defective.

Now this is JUST A GUESS; they contacted the part manufacturer and they are shipping a new one over night. Tomorrow (Tuesday EST) I will see if the problem is resolved by simply replacing the part with another.

Also: Yeah, on the phone they said the test drove the vehicle and it was accelerating by itself to speeds of up to 30 -35 MPH.

Now it's just me, but if my car is going to be revving hard enough at all times to reach speeds of over 30MPH, then it is going to SUCK GAS LIKE A BEAST!

Hopefully it is just a defective part. That would make my life easier. Maybe I should contact my shop and just have them order the part and take the car in when the part arrives.

[Colton5419]

If my car is cured tomorrow by simply swapping the part then definitely contact your shop, lets wait and see how it goes

[Colton5419]

Well I recieved a call from MIDAS and they said the car was all set, however, after test driving I noticed that all the problems still existed (this is after replacing AGAIN). So I took it back and had them install my ORIGINAL.

Those RPM problems and acceleration problems no longer exist with the ORIGINAL part.

I'll just have to wait and see if my service engine light will return.


The only issue with my original IACV I can see is after starting the car the RPMs go up to about 2000 then come back down to around 1000RPM and idle at that.

In drive etc it idles fine at 600-700rpm...any ideas?

EDIT: I did some research and "youtube" videos seem to show that it is NORMAL for it to do the 2000RPM idle and drop upon start.

[jajoyce]

Dang. My car was fixed 2 weeks ago. Would they still have the parts?

Just messing around with it, I have noticed when I turn the AC off it idols fine and no acceleration issues at all. I don't know enough as to why this is. I have never had an AC problem. I live in Arizona so for right now turning the AC off is pretty damn uncomfortable.

[Colton5419]

Dang. My car was fixed 2 weeks ago. Would they still have the parts?

Just messing around with it, I have noticed when I turn the AC off it idols fine and no acceleration issues at all. I don't know enough as to why this is. I have never had an AC problem. I live in Arizona so for right now turning the AC off is pretty damn uncomfortable.

That's EXACTLY the problem I had. I would have the RPM fluctuation without AC on, and as soon as I turned on the AC the car would have the high idol/rev and acceleration issues. (They were using CHEAP after-market brands)

Why did you have your IACV replaced in the first place? Mine simply had engine error P0507 and no real noticeable effects. I have the ORIGINAL in right now with NO problems, and I adjusted my idle screw to lower my idle - so far no service engine light either.

See about them replacing your original, maybe getting one from the junkyard? or last resort PAY $$$ for the OEM dealer part.

[bronxbombr]

i only have 4 brand new ones left

[4g63lover]

my car does the same, though, I am on a V6 TB. At first start up especially when cold, it idles @ 2k for a couple of minutes then drops to Normal idle, around 800-1000. I also have P0507 code.

[jajoyce]

That's EXACTLY the problem I had. I would have the RPM fluctuation without AC on, and as soon as I turned on the AC the car would have the high idol/rev and acceleration issues. (They were using CHEAP after-market brands)

Why did you have your IACV replaced in the first place? Mine simply had engine error P0507 and no real noticeable effects. I have the ORIGINAL in right now with NO problems, and I adjusted my idle screw to lower my idle - so far no service engine light either.

See about them replacing your original, maybe getting one from the junkyard? or last resort PAY $$$ for the OEM dealer part.

My car sunddenly just stopped and lost power on day while driving into work. I kept trying to start it and the engine would roll over and start but couldnt move anywehere. The service engine soon light went on and after I had it towed was told that the code said that the IACV was bad. They replaced it and the cost was pretty damn high as they said it was not a part that I should be getting from the junkyard and that the part should be from the dealer so I agreed to pay the price which was around $450.

Maybe it just takes a long time for the car/computer to adjust? Should I try unplugging the battery? My knowledge on care in zilch so I have no idea where the idol screw is or what it is.

[Isaurio]

I had a problem like a year ago about the rpm going down and up not a lot but you could tell. I change a lot of sensor thinking it was that. The last one i change was the MAF sensor and problem solved. Check MAF sensor. Try to clean it with maf cleaner if that dont help try to get one in the junk yard because a new one is a lots of money