Hey guys. I have a 2000 maxima. A couple days ago my car started to act funny. It was probably about 100 here in Boston last week so I had the AC on. When I had the AC on full blast my car still idled fine. When I shut the AC off immediately my car started to idle at 1500rpm's while I was at a stop light. I put my car in park and it idled at 2000 rpms. As i drove around with the AC off I realized my car went back to normal.

About 3 days ago I cleaned my throttle body with throttle body cleaner and my MAF sensor while I was at it with the MAF sensor cleaner. After I cleaned them I did notice a greater throttle response. Just yesterday my car started to mess up again. This time it was really bad. I didn't even have the AC on and after the car was warmed up on a nice run on the highway, it started to rev at 1500rpm again while on drive at a complete stop. I let go the brake pedal and the car accelerated by itself up to 2000rpms. I stopped at put it in park and the car accelerated by itself the way up to 5000rpms. I immediately shut the car off and turned it back on and the rpms went back to normal. As i drove again the same thing happened.

What can this be?

 

Get an OBD-II reader and scan for codes bro. If no codes come up, have a look at the throttle cables and make sure they are not sticking. There should be a little slack in the cables, they should NOT be tight - especially the one nearer to the front of the engine. Good luck!

 

Thanks for the advice man. Yea they aren't tight but I have no CEL's also.

 

I would check the tension on the throttle cable.

 

my brother had this problem on his 03 taurus it was his cruise control cable, maybe that is your problem.

 

Damn thats weird, be careful, and get it checked out....

 

Take it to a Toyota dealer

 

Lmao! I gotta admit I got a good kick outta this one

 

I checked the tension and everything seems to be fine. I will drive it again tomorrow morning to see if it keeps happening again.

 

So this is still happening. On a cold day it doesn't happen much. This happens more on a warmer day and I'm stuck in traffic. It idles at regular 750 RPM while on drive and as I tap the gas pedal slightly it goes up to about 1100 rpm and stays stuck there while on drive. I switch it to park or neutral and it idles at 1500-1600 rpm. I shut it off and turn it back on and it goes back to normal. If i'm still in traffic it will come back again in about 5 min. Is this a bad IAC or what can this be? I took it to a shop but a mechanic can't diagnose it because It only happens while I've been idling for a while. He hooked it up to the computer and no codes. Anyone have any ideas?

 

Anyone?

 

+1 on this, this happened in my dad's 05 Taurus as well and it was the cruise control cable. The car basically was turning cruise control on all the time and it would accelerate by itself, sometimes VERY rapidly.

It got worse as time went on and it took a very scary incident when my dad was in the car (he didn't believe this was happening when I told him) before we brought it in to get the problem fixed. What you described sounds similar to what was happening to me.

Good luck.

 

this is a floor matt issue and there is a recall on it. take it to your nearest toyota dealer......... oh wait

check the Throttle body position sensor.

 

Sounds like your throttle body is going bad. Check also your fuel cap, air leak and all hoses, wires etc. Are you getting a check engine light?

 

Your IACV (Idle Air Control Valve) is bad, I had the same problem on my 01. After the motor is hot especially after highway driving the idle becomes elevated as you stated. If the IACV is not replaced it can fry the ECU. Its the unit that sits directly underneath the throttle body.

 

I checked them all and they seem find. No I am getting no check engine light

 

IACV wont throw a code in the early stages of its failure.

 

I think I'm going to go ahead and change the IACV since I see they fail a lot on our cars. I will post back with results. Is there anything else I have to do after I change the IACV besides the idle re-learn procedure?

 

I just changed the IACV. Did the idle relearn and still the same problem but even worse now. It idle's high everywhere I go. I tried the idle relearn again 3 times and still the same. I did notice one thing though.

As I had the car running in park and I popped the hood to look at the throttle body. I checked the cables again and they were fine. I manually opened the butterfly chute and it went back down to regular idle but it would go back down slowly. Then instead of opening the butterfly again I pressed down on the lever again and noticed when I pressed it down the door closed slightly more and the idle went right back to normal. As soon as i let my hand go the idle went right back up to 2500 rpms. I pressed down and again it went back to regular idle. It seems as if the butterfly doesnt close all the way.

Could this be a bad throttle body? Or could it be a bad TPS

 

Forget about the throttle body, TPS, and anything else. It looks like a simple mechanical failure of your butterfly valve. Check the cables for full release and easy moving (the cruise control cable too), make sure they are not overtightened. Lubricate them if needed. Do the same with the valve itself, it could be partially stuck with something, also check the valve returning spring. I would also check the coolant temperature sensor. If it sends wrong data, the ECU may rise the rev through the CC cable

 

^^^^ This +100000000000,
except it actually happens on my I30, the engine will just pull itself. If you can ever pull over to see it while its happening you can see the cruise control cable will be very taught.
I loosened mine and all is good.
In the future im going to disconnect my CC entirely.

 

I have had this issue since i bought my car last august, problem was not there in the winter but once it got warm out again it started to act up. When it acts up i'm always on the road and don't pull over but yesterday before i left my driveway it started acting up again. I popped the hood and everything looked ok then i gave it gas on the throttle body and rpm's stuck up high. I pulled the throttle cable and nothing happend then i gave a slight pull to my cruise control cable and the rpm's went down. I have to do more investigating but think my cruise control cable is frayed and gets stuck once engine is hot. I'm hoping this is a simplle fix..

 

I'm having almost the same issue and what causes it in my car is IACV.
Question for you - did you get it relearned from dealer or mechanic? 2000-2001 cars are not as easy to do that with as '02-03 and IN MOST cases require that done by mechanic or dealer. I would recommend you to take out the ECU and check if the board has any chips that are burnt, as bad IACV might cause that.

 

I have had the same problem for about 2 years but is only an issue when it is hot (houston, tx).

On my 2001 Infiniti I30, I noticed that when the idle is in its "psycho" state, turning on the AC keeps it normal when in park or neutral. When I turn it off, straight up to 2500 at a minimum.

I seem to be able to easily duplicate the issue on a hot day...running errands seems to do the trick. However, I recently noticed that once the psycho state is triggered, it may or may not come back during that driving session. Sometimes I feel the car wanting to go and I can put it in park or netural and watch the RPM go up. But later, I'll try the same and it will be normal.

I have had the IACV cleaned and thought it worked. Mechanic said no relearn was necessary after he cleaned it, which gave me pause, but didn't cause any issues that I could tell. The clearning didn't work as the issue came back a a week later. Am hoping for a random fix such as the cruise control cables that were mentioned. I will try and disable and will report back.

I don't want to replace the IACV as I will need to replace an O2 sensor, some brakes and maybe some axels/boots. It's getting to the new car point for me sadly.