RalfyVA

I have a 97 es300. Lately i have noticed a stuttering or a wiggling at around 40 mph. Dont really know how to describe it, almost like a hesitation. like a jerk back and forth but real subtle. rpms arent bouncing around or anything. It does the same sort of think, but a lot more rough, when accelerating from 0mph. there is a certain amount of pedal pressure i can apply to acellerate the car and not get the jerk. Not sure if its related to the wiggle at 40mph, because the rpms bounce as the car stutters. any ideas?

moonphase

The ACIS flapper might be dirty and sluggish. It is located at the passenger side of intake manifold, by removing the five bolts. Also the PCV valve is below the ACIS and should be replaced if it doesn't rattle lightly when shaken. The rubber tube from the PCV valve dumps the blow-by gas right into the area of the ACIS valve, (flapper) so that end of the intake gets pretty nasty and should be cleaned, but don't drop anything down the intake runners when cleaning. There is also an ACIS VSV (vacuum Switching Valve) at the other end of the vacuum line of the ACIS actuator, under the engine cover, that might be failing.
Clean it and see if you get smoother operation! The gasket is supposed to be replaced if the cover is removed, but I didn't replace mine, just wiped it off and re-used. Take a digital photo of the ground wires, etc, before you start and make sure you clean and reattach all of them when you put it back together. The ACIS should function at around 4 thousand RPM. The PCM doesn't monitor the ACIS and won't set any codes if it has an issue.

JonnysES

All the above is good idea regardless for any es owner that works on his car or take it and have it done, your car will run tip top and perform so much better. Look into cleaning the Idle air control valve that's big one on issues like this. If it idles fine maybe not this another thing cold be the little idle up valve it self. The last thing I can think of is the EGR valve and systems or the VSV's that run all this stuff. After all those it may be a fuel or spark issues that the ECU may not be catching or caught yet.

Hayk

iTrader: (1)

Has anyone done a picture totorial on the ACIS flapper cleaning? I was thinking of doing it when I did my valve cover gaskets, but I didn't have a new ACIS gasket, so I decided not to mess with it.

p.s.: Nevermind, found a thread on here with some pictures
https://www.clublexus.com/forums/es3...tem-seals.html

RalfyVA

I have "cleaned" the throttle body and IAC valve twice already, each time going deeper and deeper. the first time i only cleaned the front site of the flapper and the cylindrical part of the throttle. That helped my stalling problem. then after reading your replies, i did it again and really reached in there and sprayed it good. Im just not sure the real way to do it. I've seen youtube videos where they run he car and just spray a whole can i there and I've also seen people get in there with a tooth brush while it is still attached.
as far as the PCV valve its on the other side of the engine cover, not below the flapper. And what exactly am i looking for with this part? i checked it out and noticed that it was about an 1/8th-1/4 of an inch pulled out of its hole so i pushed it back in lol. it didnt come out easy with a pull so i left it alone because i didnt know what i was doing with it anyway.
Is my best bet to take off the throttle body and do a thurough cleaning? and should the IAC be removed every time to help drain the dirty fluid? I left it in the 2nd time and have this image in my head of a puddle of mucky water crap in that little hole that goes down there

Hayk

iTrader: (1)

With the PCV Valve, you're supposed to pull it out of the valve cover and try to blow through it from one end and see if the valve operates. I'm really not sure how to diagnose it, I just know that a factory replacement part is $10. So if you suspect that it's old and you need to test it, I would just replace it.

RalfyVA

well i pulled it out and wiped off the end and blew threw it and it worked. Think im going to wait for my next check and buy a throttle gasket(sad that im that broke) and take it off and clean it and go from there. i really looked inside there when i cleaned it the 2nd time and it was super grimey. Then I'll study up on this EGR molarky i keep hearing about

Hayk

iTrader: (1)

One last engine component to clean would be your MAF sensor. Buy a can of CRC MAF cleaner and spray it down. You will need to remove it out of the intake pipe to get better access.

The EGR seems like a plausible cause. So if none of this cleaning works, start looking at the EGR system.

OceanView

I'm having a similar problem lately but mine only happens when I slightly press on the gas.
The hesitation does not happen at high RPMs or at idle. If it starts to stutter, I just press the gas a little more and it goes away. I've cleaned the IACV but it has not helped. I am gonna remove it and clean it with a wire brush to really get into the cavities.
Hope it works.

pdr

I would check for vacuum leaks. Hoses, PCV, EGR etc. Or cracks in the intake hose going from the Air Cleaner to the Throttle body. All air leaks not run through the Air flow sensor will make the engine run lean.

Also, I've seen rough running from an EGR Valve that didn't close properly. Not on my lexus but others.

That IAC from a google search only changes the length of the intake inlet length. I can't see how that would cause the symptoms you describe. Unless there was a vacuum leak in the loop that shows up when activated.

PFB

Another thing to check for is partially blocked Catalytic converter / exhaust system.

Phil

moonphase

Phil, I believe you are referring to the ACIS that changes the effective intake runner length, as the IAC controls the intake air at and around idle.

pdr

yes, you're right. Don't know how I messed that up

RalfyVA

Just bought a can of CRC, and i have to ask, Is it safe?? "DO NOT use on... most lexus vehicles". I've checked the hoses from the filter, no cracks. all the lines connecting to it seem to be ok. However when i was checking the PCV the line connected to it did look a little crusty.

OK so after searching the forums and reading different accounts, most say that doing this is pointless. Also confused about MAF sensor verses Air Flow Meters and whether or not i screwed my MAF up by unplugging it. I dont have a CEL on, but the hesitation and stuttering cant be good.

moonphase

Understandable Phil.
RalfyVA;The MAF sensor cleaner should not cause any issues. The ignition should be off and keys in your pocket before unplugging the mass air flow sensor, then remove screws and sensor while noting the direction it is originally pointing. Move away from the car and outside so the maf sensor cleaner spray doesn't get on the paint, etc. Hold the maf connector with one hand and spray into the sensor air opening and let the runoff drip back out the hole. Do not insert anything into the opening including the spray tube!! Let the sensor air dry for a couple minutes and reinstall.
Pull the PCV out and shake it, and you should hear a crisp, light, rattle sound if it is still working. Also wipe it off and blow through from both directions. Air should flow in only one direction.