Do Not Sell My Personal Information Jump to content

My Car Shudders When Idle


PK_Lex
 Share

Recommended Posts

I have a 94 LS w/ ~230k miles.

Recently I've noticed that it sometimes shudders (i.e. the engine shakes for a second or two) when I stop at a traffic light or when I start it and its sitting idle. Even after driving it for a while when I have to make a stop, it sometimes shudders.

If you have any suggestions on what could be causing it and what to do, please let me know.

Thanks.

Link to comment
Share on other sites


  • Replies 58
  • Created
  • Last Reply

Top Posters In This Topic

When was the last tuneup? Could be plug wires arcing, rotor, plugs etc. or fould injector.

The plugs were changed @ ~125k miles. I'm planning to change plugs and wires soon. What do you think about going with Vitek wires & NKG iridium plugs? What are rotors?

Do you think this is a probable cause of car shaking @ idle?

Link to comment
Share on other sites

I have a 94 LS w/ ~230k miles.

Recently I've noticed that it sometimes shudders (i.e. the engine shakes for a second or two) when I stop at a traffic light or when I start it and its sitting idle.  Even after driving it for a while when I have to make a stop, it sometimes shudders.

If you have any suggestions on what could be causing it and what to do, please let me know.

Thanks.

Check your fuel injectors. On my 93 es300 i had to replace one injector core and it now works great. i believe the electrical part of it went out on the #1 core. Your injectors probobly need to be cleaned though, if an injector core is bad you will really notice because the whole care will shake on acceleration and sound strange. get a tune-up/plugs, wires, injector cleaning, pcv valve replacement and see how it works from there. i would also suggest a diagnostic check as well. it could also be a motor mount so i would keep that in mind as well.

let me know what happens. :)

Link to comment
Share on other sites

Vitek wires & NKG iridium plugs? What are rotors?

thats a solid set up.......those vitek wires are pretty much the best, you can go with NGK plugs, i go with Desno Iridium.....they are about the same quality though

the rotors and cap from factory i beleive are denso, but the bosch replacements will work just fine, for cap and rotor its about 30 bucks.

IMO i beleive you have a vaccuum leak somewhere......that alone will cause irratic idle.

Link to comment
Share on other sites


I have a 94 LS w/ ~230k miles.

Recently I've noticed that it sometimes shudders (i.e. the engine shakes for a second or two) when I stop at a traffic light or when I start it and its sitting idle.  Even after driving it for a while when I have to make a stop, it sometimes shudders.

I have the same problem. 94LS400, 200K miles, last tuneup at 120K. Just cleaned throttle body which fixed the "engine dies after a long drive on the off ramp" problem. Now looking for a fix for the shudder at idle, and occasional shudder/hesitation when accelerating.

If you find a solution, please do tell!

Link to comment
Share on other sites

Check your fuel injectors. On my 93 es300 i had to replace one injector core and it now works great. i believe the electrical part of it went out on the #1 core. Your injectors probobly need to be cleaned though, if an injector core is bad you will really notice because the whole care will shake on acceleration and sound strange. get a tune-up/plugs, wires, injector cleaning, pcv valve replacement and see how it works from there. i would also suggest a diagnostic check as well. it could also be a motor mount so i would keep that in mind as well.

let me know what happens. :)

Thanks for the tip.

Will I have to take it to the dealer to get the injectors cleaned or is it something I can do myself? Where are they located in the engine?

I often use Chevron's FIC. Maybe before physically haiving them check or me taking them out... I'll put the BGE 44k in there and see if it makes a difference.

I'm planning to change the PCV valve myself.

The lexls site seems so good with all those tutorials in there that I'm getting passionate on doing things myself. I haven't done anything on cars before but have real interest in learning and doing.

Thanks.

Link to comment
Share on other sites

thats a solid set up.......those vitek wires are pretty much the best, you can go with NGK plugs, i go with Desno Iridium.....they are about the same quality though

the rotors and cap from factory i beleive are denso, but the bosch replacements will work just fine, for cap and rotor its about 30 bucks.

IMO i beleive you have a vaccuum leak somewhere......that alone will cause irratic idle.

According to lexls site, that's what he recommended so I'm going with Vitek and NKG.

What are rotors and caps? Where do they go?

Where are the vaccum tubes located to check for leak? How do I check if there is a leak?

Thanks.

Link to comment
Share on other sites

According to lexls site, that's what he recommended so I'm going with Vitek and NKG.

he's not a professional mechanic, just an enthusiast and an avid DIYer like most of us here.........its really just all personal preference on what parts to use. but yes he chose a really solid set up, can't go wrong with vitek and ngk

What are rotors and caps? Where do they go?

if you have to ask what the rotors and caps are, and where they go, and plan on Diying, you need to do some studying for sure........ although its a very very simple procedure even for a novice with no mechanical skills

....although first time in there, and you don't know anything about engines it will take you a fair amount of time just to get all the covers off to access the engine.

study some of his tutorials on his site, as well as our tutorials section in here, to get an idea of how our engines are layed out and accessable.

the cap i'm refering to is the distributor cap that the spark plug wires connect to....... one plug wire end connects to the plugs, the other end to the dist. cap, over time these caps can develope cracks and such, allowing moisture to get in,, there for causing irratic idle, missing, ect........the rotor is inside the dist. cap, and is easily swapped out, once the cap is off......

Where are the vaccum tubes located to check for leak? How do I check if there is a leak?

there are many vaccuum lines on our engine, most of which are at the front, just check them for cracking, make sure they are connected tightly ect......over time these can get very brittle causing them to break, and not seal correctly resulting in poor idle and other problems.

Link to comment
Share on other sites

Thanks for the info.

I know abc's of the engine, but didn't know exactly what the distributer cap and rotors look like so I can find them....thanks for clarifying it. So basically one end of wires connect to plugs and the other end goes to the cap....i can trace this.

I think i know the vaccum tubes....there are quite a few of these going around and all of these seem to be of the same size....sort of small....maybe half inch thick. I think I've seen like 4 of these connecting to somthing in the engine and all of them in parallel to each other. I heard someone said in anothr thread to spray some wd40 on these to check for leaks. Maybe I'll try that too.

Link to comment
Share on other sites

  • 2 weeks later...

Does it do it when you are in Park as well as Drive? Before you go on a wild goose chase checking all of the vacuum lines, look to see if any of your motor mounts or tranny mounts are cracked or broken.

If you're at idle and a motor mount is broken then it allows the engine to move (in place) more than normal which causes the excess vibration you are feeling. If they are OK then I would start looking at the Vacuum lines.

Link to comment
Share on other sites

Does it do it when you are in Park as well as Drive?  Before you go on a wild goose chase checking all of the vacuum lines, look to see if any of your motor mounts or tranny mounts are cracked or broken.

If you're at idle and a motor mount is broken then it allows the engine to move (in place) more than normal which causes the excess vibration you are feeling.  If they are OK then I would start looking at the Vacuum lines.

This is not a shudder -- as in vibration related. This is engine momentarily loosing rpm and power, causing a jerk, or a sequence of jerks. Happens in park as well as drive. It is like the engine starts choking up whenever there is demand for power during acceleration - especially around 1800 rpm. Once above 2200 rpm, it again runs smooth. The problem is not repeatable and I have not seen any corelation with outside temperature or humidity. It is intermittent - pretty bad one day, no problems the next day. I do see that it becomes worse when I put 89 octane vs 91 octane gas.

I am thinking it is either a clogged fuel filter or a bad injector.

Link to comment
Share on other sites

Does it do it when you are in Park as well as Drive?  Before you go on a wild goose chase checking all of the vacuum lines, look to see if any of your motor mounts or tranny mounts are cracked or broken.

If you're at idle and a motor mount is broken then it allows the engine to move (in place) more than normal which causes the excess vibration you are feeling.  If they are OK then I would start looking at the Vacuum lines.

This is not a shudder -- as in vibration related. This is engine momentarily loosing rpm and power, causing a jerk, or a sequence of jerks. Happens in park as well as drive. It is like the engine starts choking up whenever there is demand for power during acceleration - especially around 1800 rpm. Once above 2200 rpm, it again runs smooth. The problem is not repeatable and I have not seen any corelation with outside temperature or humidity. It is intermittent - pretty bad one day, no problems the next day. I do see that it becomes worse when I put 89 octane vs 91 octane gas.

I am thinking it is either a clogged fuel filter or a bad injector.

92 es300, I have a similar problem, only in drive when stationry or when just moving off, happens intermitently and seems to be getting mor noticable this last 8-900 miles. Again no problems once at speeds above 10-mph

Link to comment
Share on other sites

This is something I've never seen/heard of before, but perhaps it could be a faulty knock sensor? Feels like a stab in the dark, but I thought that since it was inconsistent, happened w/in a certain mid-RPM range and was aggrivated by lower octane fuel that it might be the ECU dialing the ignition waaaay back b/c of some freaky knock sensor readings.

Link to comment
Share on other sites

This is something I've never seen/heard of before, but perhaps it could be a faulty knock sensor?  Feels like a stab in the dark, but I thought that since it was inconsistent, happened w/in a certain mid-RPM range and was aggrivated by lower octane fuel that it might be the ECU dialing the ignition waaaay back b/c of some freaky knock sensor readings.

Does at 91 octane also. I see some improvement if I click the O/D OFF.

How do I check if the knock sensor has gone bad?

Link to comment
Share on other sites

  • 3 weeks later...

I've finally ordered spark plug wires from vitek which I should be getting in a week or so. I'm gonna get nkg IX iridium plugs to go with that. I'm thinking that the wires may be the culprit for all this off and on jerks. One thing interesting I noticed was that when it rains, it shuders and jerks a lot more not only when its idle, but also when I'm driving or accelerating. This dies down after the car has been driven for like 10-15 minutes or until it has warmed up. But even after that the off and on jerks continue when it is idle or maybe it is also happening while i'm driving and its just that they are not too noticable at that point. Very strange.

I'm also gonna get the TB cleaned. With 230k miles, i'm thinking it must be pretty messed up right now.

Thanks for your help and please keep the suggestions, tips etc coming. I'm a regular visitor here and learing a lot, but I don't post much cause i'm no expert and can't help much. But with all this learning over here i'm able to keep up with high end discussion with the mechanic and understand what he's saying. B)

Link to comment
Share on other sites

I don't post much cause i'm no expert and can't help much.  But with all this learning over here i'm able to keep up with high end discussion with the mechanic and understand what he's saying.  B)

Do let us know if changing the plugs and wires fixes your problem!

Link to comment
Share on other sites

It's taking longer than I expected to get the plug wires from Vitek - its been more than a week.  As soon as i get those I'll replace plugs, wires and clean TB.

I'll let you know the results.

If you are planning to clean the TB using the procedure on lexls.com ... here are my 2 cents.

TB deposits cause dying at idle after a long drive due to deposit blocking the clearance for idle air flow between the disk valve and the throttle body. Open the the valve by pulling on the accel lever/cable and scrape the throttle body deposits so you see a good clearance when the valve is closed. Taking the throtlle body off is a pain. You may want to avoid that excercise if not required to change the spark plugs. There is a hose that runs between the TB and the valve cover which will quite likely rupture when you try to take the TB. ( I have not yet changed the spark plugs personally.)

Link to comment
Share on other sites

  • 3 weeks later...

I finally got my car fixed. Since I got a lot of work done, it probably won't help those who were looking for what the cause may have been for shuddering. I believe it was probably spark plugs and wires because plugs were changed 100k miles ago and with 230k miles, wires were never changed.

I got the following things done by an independent mechanic in Maryland:

Spark plugs (NKG Iridium), spark plug wires (vitek), fuel injection cleaned, throttle body cleaned. Timing belt, water pump, heater control valve, thermostat ignition rotor & distribution cap replaced. And also got the complete coolant flush.

Needless to say the car runs like new and I'm loving it!!!!!!

If anyone in Maryland is looking for an independent mechanic to do this kind of work on their lexus let me know. I also got the whole front and rear suspension done by this guy 4 months back and I'm very satisfied by his work.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share




×
×
  • Create New...

Forums


News


Membership