2001 Corolla: Why Is My Car Idling Wierd?

[RyanOrion]

I have a 2001 Corolla w/ 41,000 miles on it.
Why is my car idleing wierd? It sounds fine most of the time, but once in a while it will trip out and go up and down and the car will vibrate a bit when it does that. It sounds like its misfiring. Its almost as if the timing is off just enough to make it crazy.
I have everything stock right now except my TRD muffler. I cleaned my MAF, I cleaned my injectors, I cleaned my Intake and throttle body. I checked my plugs and coils. I reset my ECU. I checked for vacume leaks. I checked for disconnected sensors. I have no clue what the heck is causing it. Anything else I could possibly check or try? Else i'm about to swap my wiring harness and fuel rail and injectors cuz i have spares.

[deizel295]

i would check your IAC motor (idle air control) if it is sticking or just getting tired, it will "surge" at idle a bit. try swapping for a known good one. or check that when it does this: 1. shut the car off, 2. restart the engine, 3. the engine should "flare" rpm's as it starts, (start and jump up to 800 or so rpms then return to normal idle) if it doesn't, the IAC motor is sticking or dead, also make sure that you cleaned this area of the t-body, it's a port just infront of the butterfly valve, and also the other end is just behind the butterfly valve in the t-body. the IAC is a valve in this port that regulates the air flowing past the throttle to maintain the proper idle. if it is plugged it may have trouble. it will also require more crank time to start and may start and stall if this is the case. try cleaning it, if all else fails try swapping with known good unit, (noot good to throw parts at it, but this part is a bugger to diagnose, i am a professional technicain, trust me) there could be other problems as well. but try this and let me know.

[RyanOrion]

OK, i thoroughly cleaned, disassembled and reassmbled everything on the throttle body and intake, and swapped out another wiring harness and the same shit is happening and now i notice that when i turn on the heater the car will idle even worse. I'm so confused. I'm about ready to bring it to the dealer, but i really hate them and they never seem to fix anything, i mean seriously, everytime i bring it in, something else breaks!!! So yeah what else should i do ? Should i actually have the IAC motor or whatever replaced? And if so, how much do those cost ?

[RyanOrion]

Umm ok so yeah engine check light now came on and all of a sudden the idling issue has gotten worse, and gas mileage has gone to hell and my car lags. I ran a ODBII check on it and found a Code: P0441 - Emissions Control System - Purge Flow Fault. I Have no idea what would cause that, so now my car is at Toyota, but yeah fun stuff!

[deizel295]

purge flow fault: the evap system has 2 solonoid operated valves. one for purging (allowing flow into the engine) and one for venting( allowing air to flow INTO the evap system) the engine sounds as though it is running rich due to the evap solonoid sticking open enrichening the mixture. i would also have them check the upstream 02 sensor to see if it is cross counting or if it is sticking low or something. but the stuck spurge valve is proally what is causing the erratic idle. the problem with these forums is that modern cars cannot be guessed at, they have to be diagnosed, cleaning and throwing parts at them is expensive and most times inneffective. so the dealership is most often the best place for it. sorry dude, dunno what to tell you, i answer threads that i recognise, I am a trained profession al diagnostic technician, but without a scan tool and the car infront of me, i am really stabbing in the dark.

[Chris Corolla S]

I guess that's why he took it to the dealer.

I change my oil and other fluids, change out brake pads and shoes, bleed the brakes, change the sparkplugs, etc, but If my car started throwing codes I'd take the fucker to the hated dealership in a minute

[RyanOrion]

Ok now i'm really pissed. I took the car into the dealership, who cleared the codes and said there is nothing wrong with my car and that the engine codes are not coming back. So i'm like ok thats funny. So i take the car and drive it down the street and fill up the gas tank and then i go to start the car and the rpms are bouncing up and down like crazy and the car eventually chokes itself and dies. This happens 3 times until i finally start driving off and it seems to run allright in drive and i put it back in park and then it starts idling rough again but not as bad as before. But at this point it seems to idle ok after 20 miles of driving. And the engine check light has not come back on yet. I just don't know what the heck is going on. As far as when i scanned with the OBDII code scanner, it came back with a P0441 before the car was brought in for service but now it seems to not be showing any codes. So yeah if it is the purge valve, where would that be located and how would i replace that? I just want my car to run right.

[Chris Corolla S]

This shit is why I hate dealerships.

[deizel295]

purge solonoid valve is usually located on the bottom of the evap cannister, which usually looks like a black coffee can or a plastic box with hises running to and from it. p0441 code eh? hmmm, that IS an evap code. i dunno what else to tell you, the reason why it runs crappier when you filled it up is because the valve is proally stuck open, and it is not allowed to open with a full tank of gas due to the high probability of drawing raw fuel into the evap system. the dealership is a bunch of fucksticks if they cannot diagnos this issue. jesus. i would replace the valve and solonoid. that SHOULD fix the problem, like i said, it's not here with me. but with the codes and symptoms thats what you got, a stuck open purge valve. on the bottom of the hood SHOULD be an evap system diagram showing component locations and thier functions, but we can only hope. so let me know how it goes, replace your plugs and change your oil when you do this. the issue of raw fule entering when only a light amount of vapor is suppossed to be coming in can foul plugs ( yes on a modern EFI engine ) and "wash" down the cylinders, dilluting your oil, lowering the effectivness of your oil. hope all goes well man, i'll say a prayer for ya.

[RyanOrion]

So where would i get these parts? Directly from Toyota or can i go to a normal parts place and get em there? I'm gonna start looking around, but I figured if anyone new off the top of their head, that'd save me some time....

[deizel295]

Not to be sounding like a name brand bible basher, but these parts are specific to each vehicle, and if weird ones (sometimes aftermarket parts are junk, sorry to all who sell 'em) you'll never get rid of these issues. sorry to say it, go with toyota originals only. if yo can find out who built them for toyota (bosch for example) then buy that aftermarket brand. but i doubt any parts stores will even have them listed. but go toyota, it's the sfaest bet, and they work perfectly, nuf said.

[RyanOrion]

Ouch, I have to buy the entire charcoal canister for $270, cuz the valve is part of it, and then the solenoid is the other part $90. So yeah these parts should be covered by the warranty, but the dealership won't do anything about it until the engine check light comes back on, and Im thinking the reason its not is cuz its intermittent and the valve is sticking open every so often. But yeah fun stuff.....

[Chris Corolla S]

Well maybe you should wait and see if the CEL comes on again, then check the code, and if it's the same take it in and say "I want this and this part replaced under warranty."...

[RyanOrion]

Ok now i notice alot of freakin carbon coming out of the exhaust, like the back of my car is totally covered in residue...... fun stuff!!!

[RyanOrion]

Woohoo all fixed, took it to another dealership, that always does the trick. But yeah it was a bad valve and cross VSV hose. So far so good!