Rough Idle When In Gear

[SHUMIF1]

wondering if anyone has this issue. 2001 rx300 95k miles, timing belt done at 90k .when my car has warmed up i get a vibration in the whole car and u can feel it in your ears like when u crack a window open a little at high speeds.dealer said that it sounds like a broken motor mount. any ideas what could couse this ?

[Steve]

it could be.. best way to check is open the hood, turn car on.. press brakes with left foot and slowly try and accelerate (be real careful, do it with room at front of the car) ask a friend to look at the engine while doing this (maybe film it with phone).. if the engine has a lot of play and movement then the mount is gone.

Dont try and drive the car.. just a few small bursts of the accelerator to see if the engine moves about.

[SHUMIF1]

thanks steve, i bought a front motor mount. i'll let you know if that does it.

[lenore]

One other thing is check the flex pipe on the exhaust below the engine...The coupling breaks and gives you the impression of more vibration...And more noise. Hold a piece ol paper next to it while running and it should not move....The flex pipe can be replaced at any reputable muffler shop...

[SHUMIF1]

lenore- the flex pipe was replaced befor i bought the car but with a solid flex pipe not like the original one that looks like a mesh. i will check it out ,thanks. I did replace the fron engine mount , although the diaphram was collapsed it did not resolve the issue.

[lenore]

What about the upper stabilizer mount on the passenger side on top of the engine near the power steering fluid and top timing belt cover? Did you replace that mount..?

[SHUMIF1]

lenore, that was the first one i checked and the flex pipe that i mentiond befor was replaced by a mesh type. I ordered the vacume celenoid that goes along with the fron mount . my next step is the rear mount....we shall see....

[lenore]

Ok I is the vibration at idle? or on the road.....Sorry I had a vibration issue on my old RX300 and it turned out being the drive shaft to the rear (note AWD).

[SHUMIF1]

just at idle or in gear when stationary , once i bring up the RPMs it stops or when i start moving it goes away.

[SHUMIF1]

ok, changed the selenoid for the front mount and no improvement , did the throttle body and idle cleaning but no improvement. I had it on a lift and put preasure on the front pipe by the mesh flex and it seemed to go away but the rest of the exhaust vibrates still. also if you listen to the exhaust coming out of the rear mufler it also sounds strange. i know it sounds funny to say it sounds strange but i worked on cars for 28 years and it just doesnt sound right. maybe something is clogged in the exhaust. also i had the dealer change the timming belt last may and there is a a sound comming from the plastic timing covers but almost like metal on metal rubbing together., maybe something in the timing belt area is giving me this vibration problem.

Anyone know a good lexus mechanic in bergen county new jersey area ?

[SurfinDave]

If you have odd sounding exaust, its quite possible one of the CAT's is clogged. That bad metal grinding sound coming from your timing cover is most likely a bad bearing on the one of the idlers or the water pump, but if it is serious enough of a problem to cause as engine vibration, you better get that checked before it snaps your timing belt and you lose your engine. Someone will have to explain why an exhaust or a motor mount issue would cause an problem when the engine is warmed up and not when it is cold. One would think the viabration could be the result of poor idling as any inbalance in the engine smoothness would cause some shudder thought the entire vehicle. Maybe that explians the odd exhaust noise, the normal idle pulsation coming out is being interupted.

Just a thought, hope it helps.........

[UCF3]

Does it sound like it's sputtering when you're stopped at a traffic light?

[2005_RX330]

You mentioned that the flexible exhaust coupling has been replaced with a solid one (if I read the posting correctly). A solid pipe will cause the entire exhaust system to vibrate with the engine and, in certain circumstances, make the vibration more evident to the driver. By way of example, I once owned a 1996 Honda Accord which had an (OEM) solid intermediate pipe in the exhaust system, i.e., no flexible coupling. Honda later wrestled with owner complaints of noise and vibration in that model but never instituted a proper fix; I eventually had that pipe replaced with a flexible coupling which improved (reduced) the amount of driver-perceived vibration greatly. It's worth noting that Honda's re-design of the Accord in 1998 incorporated a flex pipe in the exhaust instead of the solid pipe, eliminated the problem which was designed-in to the 1996-era models.

If you had an engine miss it might contribute to your problem, but it would also trigger a error in the ECU and illuminate the appropriate (Service Engine Soon?) light. An injector issue could contribute to engine roughness, particularly near idle, but might not necessarily cause the ECU to generate an error.

[NJerseyDan]

Hey buddy,

I've got an 01' 300, that I've had for about 6 years. I can save you some time and effort on yours. I bought it with 60K and it started doing the vibration thing around 75K. I've changed both motor mounts, and the tranny mount. Put a New IACV in. Had the Injectors cleaned at PepBoys on their super duper machine. Changed the Drive shaft Support bearings. Replaced that upper engine support strut. Had two exhaust shops tell me the problem wasn't exhaust. And two transmission shops tell me it wasn't transmission. Taken it to 3 lexus dealers, to get different opinions, and wrote a letter to Lexus. When It's particularly annoying I drive around with my auto scanner plugged in, watching live data. But I haven't seen anything on there to point to the cause. Like your Rex, If I give it the slightest gas, it will smooth right out. I've scoured these forums off/on for years now trying to find a solution to it! I give up for a while, then I come back.

I've been considering changing the Harmonic Balancer. There's a company called Fluidampr, that makes some super high tech ones, but unfortunately not for our car. But if I find something like that, I may try it out. I've also been doin some research on ECU remapping. If you could just raise the idle 60rpm or so, I think it would eliminate the vibration(adjusting the screw on the throttle body will not do it). Other than that annoying vibration, my Rex has been a great car. Put on 100K since I bought him.

[SHUMIF1]

Thanks guys , i had a 99 rx300 and had the same problem and never figured it out. it drives me nuts..lol..NJerseyDan did u change your flex pipe yet. if so did it make that vibrate it more or less ? someone changed mine befor i bought the car and im wondering if its just not lined up right or not the right flex material.

[SHUMIF1]

UCF3 . no it never sputters.

[NJerseyDan]

shumif, I don't think I ever changed it. But I do remember climbing under and checking it out, a few years ago. And I'm pretty sure it was the braided steel, flex type connection. And I think I wrote it off after the two exhaust shops told me the problem wasn't exhaust. Probably worth a try though. Seems some of things I've tried, have worked for other Rex's. Like Lenore up there had the driveshaft supports done, and straightened it out.

I also remember seeing on a forum that some guy had a sensor changed at his dealership, and that fixed it. He didn't say what sensor it was, and he has never replied to any posts on that thread since.. sob

[bedrock8x]

EGR valve leaking will cause rougth idle. Car will normal except idling rougth after car warms up.

[danfox]

Did this start after the belt change? Did fuel mileage drop. Could have jumped a tooth on the timing belt due to not being tensioned high enough. Could also have a failing idler on the belt letting the belt slack a bit and jump and explaining the noise from the cover.

[SHUMIF1]

it did get a little worse after the belt change but every mechanic i spoke to said even if it was off 1 tooth a light would come on the dash . these computers are so sensative . NJerseyDan- one mechanic told me if one of the pulleys berrings.. ALT. PS pump.. is goin it will vibrate through the whole car at certain RPMs. have u checked yours.. mine is noisy. i'll check the EGR valve.

[SHUMIF1]

I read that it might be the Torque Converter, what do you think ?

[NJerseyDan]

I'd heard the same about the timing belt- one tooth off will throw a code. But I didn't notice any change after mine was done, anyhow- vibrated before and after. I had Lexus do mine. Pat, I don't think our Rex's have EGR. But we do have a PCV valve. And mine was fine when I checked it. Shumif, I've never checked any pulleys, but I do have a occasional belt squeal when the ac kicks in cold weather, despite both belts being adequately tight, and in good condition. I'd wondered before if a bearing could be bad. So that's interesting... you might be onto something there.

I'd written off the torque converter because those two tranny shops told me it wasn't tranny related. But I did read in a forum a while ago about an improperly installed torque converter causing vibration. And the tranny/TC in our truck is prone to an early grave.

Danfox, I don't know a whole lot about the timing system. Could a little bit of slack in the belt cause a problem?

My engine has gotten noisier also. Theres a sound that I would describe as a high speed chatter. I was thinking the valves needed adjustment. That's what it sounded like to my untrained ear.

[danfox]

A little slack is not a problem until it jumps a tooth, then a big problem. A little like being pregnant or not.

A belt squeal is not a good thing to have....one of them needs to be snugged up, but the timing belt will not squeal. If you hear he squeal, it is an accessory belt.

[SHUMIF1]

i also read that it could be the torque converter, ?

[SHUMIF1]

sorry didn't see the other thread