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My Car Shudders When Idle


PK_Lex

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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.

Thanks for your reply. I see that you did not change the fuel filter. So it eliminates that as a cause. Can you confirm? Thanks.

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I didn't change the fuel filter.

I think clogged fuel injectors could cause these symptoms too, so make sure they are cleaned. I've heard BGE fuel injector cleaner works well, but haven't used it myself. So if you don't want to spend money getting it cleaned by a mechanic (however I would recommend that you do), see if using it makes a difference. I think it goes for around $15.

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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.

WOW YO PGUPTA I HAVE A 93 LEXUS LS400 240,000 MILES ON THE BAD BOY AND I HAVE THE EXACT SAME PROBLEM AS YOU BRO. WHEN IDELING AT A RED LIGHT IT OCCASIONALLY SHUDDERS FOR A QUICK SECOND EVERY MINUTE OR SO. BUT WHEN IM DRIVING I FIND THAT AT 1800 RPM'S IT STUTTERS ALITTLE WHILE GIVING GAS LIKE A TEMPORARY LOSS OF POWER IN A JERKING MOTION ITS A WEIRD FEELING UNTILL IT GETS OVER THE 2000 RPM THEN ITS SMOOTH SAILING. WELL I JUST PUT A FUEL INJECTION CLEANER INTO MY GAS TANK (SUPPOSEDLY THE BEST ONE) BUT STILL STUTTERING. PLEASE I NEED HELP AND I DONT HAVE A LOT OF $$$$ TO GO OUT AND TRY FIXING EVERYTHING TILL I GET IT RIGHT. PLEASE GET BACK TO ME CUZ ITS STARTTING TO GET REAL FRUSTRATING AS YOU PROBABLY ALREADY KNOW.

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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.

WOW YO PGUPTA IM A NEW MEMBER HERE AND I HAVE A 93 LEXUS LS400 240,000 MILES ON THE BAD BOY AND I HAVE THE EXACT SAME PROBLEM AS YOU BRO. WHEN IDELING AT A RED LIGHT IT OCCASIONALLY SHUDDERS FOR A QUICK SECOND EVERY MINUTE OR SO. BUT WHEN IM DRIVING I FIND THAT AT 1800 RPM'S IT STUTTERS ALITTLE WHILE GIVING GAS LIKE A TEMPORARY LOSS OF POWER IN A JERKING MOTION ITS A WEIRD FEELING UNTILL IT GETS OVER THE 2000 RPM THEN ITS SMOOTH SAILING. WELL I JUST PUT A FUEL INJECTION CLEANER INTO MY GAS TANK (SUPPOSEDLY THE BEST ONE) BUT STILL STUTTERING. PLEASE I NEED HELP AND I DONT HAVE A LOT OF $$$$ TO GO OUT AND TRY FIXING EVERYTHING TILL I GET IT RIGHT. PLEASE GET BACK TO ME CUZ ITS STARTTING TO GET REAL FRUSTRATING AS YOU PROBABLY ALREADY KNOW.

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WOW YO PGUPTA IM A NEW MEMBER HERE AND I HAVE A 93 LEXUS LS400 240,000 MILES ON THE BAD BOY AND I HAVE THE EXACT SAME PROBLEM AS YOU BRO.

I have tried an aggressive fuel injector cleaner treatment with zero effect. So, it is quite likely not the primary cause. I cleaned the Throttle body with zero effect on this problem. (Fixed the other problem of engine dying at the off ramp after a long drive.)

At this point, I bought a new fuel filter but I will not change it for now. Next thing I will do is change the spark plugs and wires only. I intend to fix one thing at a time and really nail it down because I am so annoyed with this problem! It will be a few months though since this is my third car and gets attention after everything else in life.

I will definitely come back to this thread and post my findings. Keep checking.

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IM A NEW MEMBER , LEARNING HOW TO POST

Then you need to be told. STOP YELLING AT FOLKS. When you use all caps it is the same as yelling. It is not nice. Turn your Cap key off.

hahaha well sorry man I didnt know you could "YELL" over the computer but I will lower case everything from now on just for you................ ok now getting back to the discussion at hand. To let you all know I brought my 93 ls400 the other day to the lexus dealership to put it on the diognostic machine and the results were it said I have a faulty "Air Flow Meter" and "Idle Control Valve". Now lexus wants a rediculous amount for these parts $1300 for the AFM and $800 for the ICV. Im going to see if I can find one locally for a cheaper price. But I recommend that everyone with this problem also checks there intake air filter which might also be the villan here because when I checked my it was dirty beond belief. So I will be replacing that also.

I will keep you posted.

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...the lexus dealership to put it on the diognostic machine and the results were it said I have a faulty "Air Flow Meter" and "Idle Control Valve". ...also checks there intake air filter

my air filter is brand new and not related to this problem at hand. no harm replacing a dirty one though. air flow meter and idle control valve seem a remote possibility for this problem at hand ... but do keep us posted as to what you replace and what the effect is.

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  • 2 weeks later...

hey guys ok a few updates , i put in a new air flow meter that lexus said was the problem and that did nothing still the same shuddering and occasional stalling. i also replaced the air filter cuz mine was jampacked with dirt , helped with power but still the problems exist. so I am currently looking for a "idle control valve" currently cant find one other than the dealer but , to much dinero $$. Im asking you guys if anyone knows where i might be able to get one new or a working used one. for my 93 ls400 90-94 will fit. Please get back to me if you can help my car is off the road b/c of this problem. you can reply here or email me at nyinfamous2k2@aol.com . thanks i appreciate it .

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Please get back to me if you can help my car is off the road b/c of this problem. you can reply here or email me at  nyinfamous2k2@aol.com . thanks i appreciate it .

From all I can make of this problem, you need new spark plugs and cables. Why not do that instead? How many miles since the last change? If over 80K, it may be the better bet.

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  • 2 weeks later...
Please get back to me if you can help my car is off the road b/c of this problem. you can reply here or email me at  nyinfamous2k2@aol.com . thanks i appreciate it .

Well, it was a nice sunny weekend and I decided to get under the hood. My intention was to just replace the spark plugs and see if that fixed the problem. Once I opened the covers, it was evident that I was duped some 4 years ago! I had the plugs and cables changed the last time around. I found that I still had the original cables from 1993 in the car. Needless to say, I snapped two of those just trying to pull them off the plugs. The plugs still looked very clean which tells me that everything else is running good in cylinders.

Special tools needed: You need a 5/8th inch deep (6" deep) spark plug socket (had the rubber catch to snugly grasp the plug) to do this job right. Also, use dielectric grease at the cable contacts. Check plugs for 0.044 inch gap. A long slender pair of nose pliers will be handy if you snap the cable end on the plug. You will have to pull the broken piece off before you can reach the bottom of the plug with your socket.

All said and done - the hesitation, jerking, shuddering is all gone now. The engine runs smooth. Conclusion -- old and bad spark plug cables was the likely cause.

I did not have the patience to mail order NGK-Iridum and Vitek cables. I went with the local AC Delco after market cables, autolite double platinum plugs from the local parts shop. Will see how long these last. While I was at it, I did my annual Mobil 1 synthetic oil change. I change engine oil every 15 to 20 thousand miles, have always used synthetic oil only. Every year the old oil flows out smooth and clean with good viscosity still intact.

This is one of my first LS400s (1994) and I have now over 200K miles on it. Still runs like a champ! As you can see, I am pushing the limits of sanity here with oil change etc. This engine is very well designed. The less you muck with it, the longer it will last!

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Good to know you solved the problem. Plugs and wires are a likely cause of these symptoms from what I had gathered too.

15-20k miles interval between oil changes seem to be on the high side. But if it comes out clean then I guess its reasonable to do so at that point.

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  • 2 weeks later...
Good to know you solved the problem. 

Me too! Thanks for starting the thread.

Whats up all. ok I did a full tune up on my 93 ls400 including plugs wires air filter oil filter , fuel filter, both caps and rotors. all parts purchased from lexus. Car runs a hell of alot better , no more studdering while driving and alot more power, BUT..... I still have idle problems, only hesitates at complete stop. also if I thro her into neutral at a red light the idle jumps up to 3k rpms. I hear the idle control valve needs to be replaced or cleaned, so b4 I buy one for $900 from lexus im having my mech. clean it as we speak so hopefully that will solve this problem. will keep u updated.

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Good to know you solved the problem. 

Me too! Thanks for starting the thread.

I still have idle problems, only hesitates at complete stop.

You need to do a throttle body cleanup. I used some oven cleaner to dissolve all the carbon deposit and the car runs great after that. No more stalling at idle after a long drive. see www.lexls.com for procedure to get to the throttle body.

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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.

Hey PK_Lex,as you said,how much you spent for the labor?And how long it gonna take?2hours?3hours?

Thanks

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Please get back to me if you can help my car is off the road b/c of this problem. you can reply here or email me at  nyinfamous2k2@aol.com . thanks i appreciate it .

Well, it was a nice sunny weekend and I decided to get under the hood. My intention was to just replace the spark plugs and see if that fixed the problem. Once I opened the covers, it was evident that I was duped some 4 years ago! I had the plugs and cables changed the last time around. I found that I still had the original cables from 1993 in the car. Needless to say, I snapped two of those just trying to pull them off the plugs. The plugs still looked very clean which tells me that everything else is running good in cylinders.

Special tools needed: You need a 5/8th inch deep (6" deep) spark plug socket (had the rubber catch to snugly grasp the plug) to do this job right. Also, use dielectric grease at the cable contacts. Check plugs for 0.044 inch gap. A long slender pair of nose pliers will be handy if you snap the cable end on the plug. You will have to pull the broken piece off before you can reach the bottom of the plug with your socket.

All said and done - the hesitation, jerking, shuddering is all gone now. The engine runs smooth. Conclusion -- old and bad spark plug cables was the likely cause.

I did not have the patience to mail order NGK-Iridum and Vitek cables. I went with the local AC Delco after market cables, autolite double platinum plugs from the local parts shop. Will see how long these last. While I was at it, I did my annual Mobil 1 synthetic oil change. I change engine oil every 15 to 20 thousand miles, have always used synthetic oil only. Every year the old oil flows out smooth and clean with good viscosity still intact.

This is one of my first LS400s (1994) and I have now over 200K miles on it. Still runs like a champ! As you can see, I am pushing the limits of sanity here with oil change etc. This engine is very well designed. The less you muck with it, the longer it will last!

Congrats.Good for your car.

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  • 2 weeks later...

its been about 2 months not and who knows how much $$$$ ive spent already and still no selution. So here we go; so far in effort to correct this problem i started small and inexpensive and worked my way up. I have replaced the spark plugs, wires, oil filter , fuel filter, air filter, caps, and rotors, NOT FIXED. So I cleaned the throttle body, and replaced the Air Flow Meter. NOT FIXED. now i just had the dealer put in a new idle control valve where they said that was definalty the problem. funny, they were wrong, because I stalled out on the way home from the dealership. So back the car went, they are currently running all types of tests and diognostics on it. hopfully there genius mechanics will resolve this problem and I can report good new with the cure to all of you. but any1 come across some answer please keep us all posted.

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its been about 2 months not and who knows how much $$$$ ive spent already and still no selution. So here we go; so far in effort to correct this problem i started small and inexpensive and worked my way up. I have replaced the spark plugs, wires, oil filter , fuel filter, air filter, caps, and rotors, NOT FIXED. So I cleaned the throttle body, and replaced the Air Flow Meter. NOT FIXED. now i just had the dealer put in a new idle control valve where they said that was definalty the problem. funny, they were wrong, because I stalled out on the way home from the dealership. So back the car went, they are currently running all types of tests and diognostics on it. hopfully there genius mechanics will resolve this problem and I can report good new with the cure to all of you. but any1 come across some answer please keep us all posted.

Dare I suggest "clogged fuel injectors" ? Sorry to hear about all what you have gone through.

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Hi All: I read through the topic with much interest as I am at the end of my patience! I have a 1997 ES300 with 122k miles on it. Here is a quick version of my story - I had (and have) the same shudder/idle problem. I think it happens when I am coasting downhill at 50 to 70 mph. I can feel it happening and when I finally come to a stop (park or idle) my car is choking, well rough idling below normal idle speed (smell of gasoline and all). If I turn the car off for about to 4 to 5 minutes problem goes away, always!!

Now, I had this problem for over 2 years now, I had numerous things done trying to fix it. To boot, my engine seized on me 4000 miles ago, so I paid $$$$ to get another engine and here is the kicker - IT STILL HAS THE SAME PROBLEM!! My mechanic changed all reasonable items with the engine change - timimg belt, spark plugs, wires, intake, water pump, PCV vavle among others. I recently got the IACV changed after reading the forums here - STILL SAME PROBLEM. Last week, new Oxygen Sensor (front only), still the same problem!! I had injection service and tuning all done with the new engine.

What else is left? I thought Lexus is supposed to be reliable... :cries:

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Hi All:  I read through the topic with much interest as I am at the end of my patience!  I have a 1997 ES300 with 122k miles on it.  Here is a quick version of my story - I had (and have) the same shudder/idle problem. I think it happens when I am coasting downhill at 50 to 70 mph. I can feel it happening and when I finally come to a stop (park or idle) my car is choking, well rough idling below normal idle speed (smell of gasoline and all). If I turn the car off for about to 4 to 5 minutes problem goes away, always!!

Now, I had this problem for over 2 years now, I had numerous things done trying to fix it.  To boot, my engine seized on me 4000 miles ago, so I paid $$$$ to get another engine and here is the kicker - IT STILL HAS THE SAME PROBLEM!!  My mechanic changed all reasonable items with the engine change - timimg belt, spark plugs, wires, intake, water pump, PCV vavle among others.  I recently got the IACV changed after reading the forums here - STILL SAME PROBLEM.  Last week, new Oxygen Sensor (front only), still the same problem!!  I had injection service and tuning all done with the new engine.

What else is left? I thought Lexus is supposed to be reliable...  :cries:

Your problem seems to be a choked up throttle body. When was the last time you had it cleaned?

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Your problem seems to be a choked up throttle body. When was the last time you had it cleaned?

I talked to my mechanic, he says it was cleaned when the engine was changed a couple of months ago. It is owrth noting that with in a week of the new engine being installed, I noticed the problem.

Now the mechanic thinks it is "Mass Airflow Sensor"... The engine code was an O2 code, but one of the O2 senors was already changed. He thinks the code is a symptom, not a cause. I tend to agree... But the fix proposed would be just an educated guess, again!

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Your problem seems to be a choked up throttle body. When was the last time you had it cleaned?

I talked to my mechanic, he says it was cleaned when the engine was changed a couple of months ago. It is owrth noting that with in a week of the new engine being installed, I noticed the problem.

Now the mechanic thinks it is "Mass Airflow Sensor"... The engine code was an O2 code, but one of the O2 senors was already changed. He thinks the code is a symptom, not a cause. I tend to agree... But the fix proposed would be just an educated guess, again!

Dayaln; since we have very similar problems let me suggest that chances are if you replace the Mass Air Flow Meter, it wont fix the problem. from my experience, just some info, the part from lexus runs about $700-$800, I purchased one from ebay for about $250. when lexus ran a diognostiscs on my car they said the problem was the MAFM and the Idle Control Valve. since then, ive replaced both and still the problem continues. I mean things might be different for you Dayaln but its just some info to help you on your decision for your next move. later

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Your problem seems to be a choked up throttle body. When was the last time you had it cleaned?

I talked to my mechanic, he says it was cleaned when the engine was changed a couple of months ago. It is owrth noting that with in a week of the new engine being installed, I noticed the problem.

Now the mechanic thinks it is "Mass Airflow Sensor"... The engine code was an O2 code, but one of the O2 senors was already changed. He thinks the code is a symptom, not a cause. I tend to agree... But the fix proposed would be just an educated guess, again!

Dayaln; since we have very similar problems let me suggest that chances are if you replace the Mass Air Flow Meter, it wont fix the problem. from my experience, just some info, the part from lexus runs about $700-$800, I purchased one from ebay for about $250. when lexus ran a diognostiscs on my car they said the problem was the MAFM and the Idle Control Valve. since then, ive replaced both and still the problem continues. I mean things might be different for you Dayaln but its just some info to help you on your decision for your next move. later

Thanks for the advise LEGENDICON... I will keep it in mind. I am off to test drive a C320, as I said, I am very close to throwing in the towel...

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